Heavy docker-app loading refactoring

- introduces a `types` package, moving it from `internal/types`
- introduces a `loader` package, with function to lead each type of
  app (folder, tarball, single-file) — only docker image is still in
  `internal/packager`.
- introduces a small `compose` helper package
- updates some `settings` functions
- split `internal/render` into `render` package and `internal/inspect`

Signed-off-by: Vincent Demeester <vincent@sbr.pm>

cmd/docker-app/deploy.go

@@ -3,8 +3,8 @@ package main
 import (
 	"github.com/docker/app/internal"
 	"github.com/docker/app/internal/packager"
-	"github.com/docker/app/internal/render"
-	"github.com/docker/app/internal/types"
+	"github.com/docker/app/render"
+	"github.com/docker/app/types"
 	"github.com/docker/cli/cli"
 	"github.com/docker/cli/cli/command"
 	"github.com/docker/cli/cli/command/stack"
@@ -71,7 +71,7 @@ func runDeploy(dockerCli command.Cli, flags *pflag.FlagSet, appname string, opts
 	}
 	stackName := opts.deployStackName
 	if stackName == "" {
-		stackName = internal.AppNameFromDir(app.Path)
+		stackName = internal.AppNameFromDir(app.Name)
 	}
 	return stack.RunDeploy(dockerCli, flags, rendered, deployOrchestrator, options.Deploy{
 		Namespace:    stackName,

cmd/docker-app/helm.go

@@ -6,7 +6,7 @@ import (
 	"github.com/docker/app/internal"
 	"github.com/docker/app/internal/helm"
 	"github.com/docker/app/internal/packager"
-	"github.com/docker/app/internal/types"
+	"github.com/docker/app/types"
 	"github.com/docker/cli/cli"
 	cliopts "github.com/docker/cli/opts"
 	"github.com/spf13/cobra"

cmd/docker-app/image-add.go

@@ -6,8 +6,8 @@ import (
 	"github.com/docker/app/internal"
 	"github.com/docker/app/internal/image"
 	"github.com/docker/app/internal/packager"
-	"github.com/docker/app/internal/render"
-	"github.com/docker/app/internal/types"
+	"github.com/docker/app/render"
+	"github.com/docker/app/types"
 	cliopts "github.com/docker/cli/opts"
 	"github.com/spf13/cobra"
 )
@@ -41,7 +41,7 @@ subdirectory.`,
 			if err != nil {
 				return err
 			}
-			if err := image.Add(app.Path, args[1:], config); err != nil {
+			if err := image.Add(app.Name, args[1:], config); err != nil {
 				return err
 			}
 			// check if source was a tarball
@@ -60,7 +60,7 @@ subdirectory.`,
 					return err
 				}
 				// source was a tarball, rebuild it
-				return packager.Pack(app.Path, target)
+				return packager.Pack(app.Name, target)
 			}
 			return nil
 		},

cmd/docker-app/image-load.go

@@ -17,7 +17,7 @@ func imageLoadCmd() *cobra.Command {
 				return err
 			}
 			defer app.Cleanup()
-			return image.Load(app.Path, args[1:])
+			return image.Load(app.Name, args[1:])
 		},
 	}
 }

cmd/docker-app/inspect.go

@@ -1,8 +1,8 @@
 package main
 
 import (
+	"github.com/docker/app/internal/inspect"
 	"github.com/docker/app/internal/packager"
-	"github.com/docker/app/internal/render"
 	"github.com/docker/cli/cli"
 	"github.com/docker/cli/cli/command"
 	"github.com/spf13/cobra"
@@ -20,7 +20,7 @@ func inspectCmd(dockerCli command.Cli) *cobra.Command {
 				return err
 			}
 			defer app.Cleanup()
-			return render.Inspect(dockerCli.Out(), app.Path)
+			return inspect.Inspect(dockerCli.Out(), app)
 		},
 	}
 }

cmd/docker-app/merge.go

@@ -57,9 +57,9 @@ func mergeCmd(dockerCli command.Cli) *cobra.Command {
 					return errors.Wrap(err, "error scanning application directory")
 				}
 				if len(extra) != 0 {
-					return fmt.Errorf("refusing to overwrite %s: extra files would be deleted: %s", extractedApp.OriginalPath, strings.Join(extra, ","))
+					return fmt.Errorf("refusing to overwrite %s: extra files would be deleted: %s", extractedApp.Path, strings.Join(extra, ","))
 				}
-				mergeOutputFile = extractedApp.OriginalPath + ".tmp"
+				mergeOutputFile = extractedApp.Path + ".tmp"
 			}
 			var target io.Writer
 			if mergeOutputFile == "-" {
@@ -70,7 +70,7 @@ func mergeCmd(dockerCli command.Cli) *cobra.Command {
 					return err
 				}
 			}
-			if err := packager.Merge(extractedApp.Path, target); err != nil {
+			if err := packager.Merge(extractedApp, target); err != nil {
 				return err
 			}
 			if mergeOutputFile != "-" {
@@ -78,10 +78,10 @@ func mergeCmd(dockerCli command.Cli) *cobra.Command {
 				target.(io.WriteCloser).Close()
 			}
 			if inPlace {
-				if err := os.RemoveAll(extractedApp.OriginalPath); err != nil {
+				if err := os.RemoveAll(extractedApp.Path); err != nil {
 					return errors.Wrap(err, "failed to erase previous application")
 				}
-				if err := os.Rename(mergeOutputFile, extractedApp.OriginalPath); err != nil {
+				if err := os.Rename(mergeOutputFile, extractedApp.Path); err != nil {
 					return errors.Wrap(err, "failed to rename new application")
 				}
 			}

cmd/docker-app/push.go

@@ -18,7 +18,12 @@ func pushCmd() *cobra.Command {
 		Short: "Push the application to a registry",
 		Args:  cli.RequiresMaxArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {
-			return packager.Push(firstOrEmpty(args), opts.namespace, opts.tag)
+			app, err := packager.Extract(firstOrEmpty(args))
+			if err != nil {
+				return err
+			}
+			defer app.Cleanup()
+			return packager.Push(app, opts.namespace, opts.tag)
 		},
 	}
 	cmd.Flags().StringVar(&opts.namespace, "namespace", "", "namespace to use (default: namespace in metadata)")

cmd/docker-app/render.go

@@ -6,8 +6,8 @@ import (
 
 	"github.com/docker/app/internal"
 	"github.com/docker/app/internal/packager"
-	"github.com/docker/app/internal/render"
-	"github.com/docker/app/internal/types"
+	"github.com/docker/app/render"
+	"github.com/docker/app/types"
 	"github.com/docker/cli/cli"
 	"github.com/docker/cli/cli/command"
 	cliopts "github.com/docker/cli/opts"

cmd/docker-app/save.go

@@ -21,7 +21,12 @@ func saveCmd(dockerCli command.Cli) *cobra.Command {
 		Short: "Save the application as an image to the docker daemon(in preparation for push)",
 		Args:  cli.RequiresMaxArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {
-			imageName, err := packager.Save(firstOrEmpty(args), opts.namespace, opts.tag)
+			app, err := packager.Extract(firstOrEmpty(args))
+			if err != nil {
+				return err
+			}
+			defer app.Cleanup()
+			imageName, err := packager.Save(app, opts.namespace, opts.tag)
 			if imageName != "" && err == nil {
 				fmt.Fprintf(dockerCli.Out(), "Saved application as image: %s\n", imageName)
 			}

cmd/docker-app/split.go

@@ -24,16 +24,16 @@ func splitCmd() *cobra.Command {
 			defer extractedApp.Cleanup()
 			inPlace := splitOutputDir == ""
 			if inPlace {
-				splitOutputDir = extractedApp.OriginalPath + ".tmp"
+				splitOutputDir = extractedApp.Path + ".tmp"
 			}
-			if err := packager.Split(extractedApp.Path, splitOutputDir); err != nil {
+			if err := packager.Split(extractedApp, splitOutputDir); err != nil {
 				return err
 			}
 			if inPlace {
-				if err := os.RemoveAll(extractedApp.OriginalPath); err != nil {
+				if err := os.RemoveAll(extractedApp.Path); err != nil {
 					return errors.Wrap(err, "failed to erase previous application directory")
 				}
-				if err := os.Rename(splitOutputDir, extractedApp.OriginalPath); err != nil {
+				if err := os.Rename(splitOutputDir, extractedApp.Path); err != nil {
 					return errors.Wrap(err, "failed to rename new application directory")
 				}
 			}

cmd/docker-app/validate.go

@@ -2,8 +2,8 @@ package main
 
 import (
 	"github.com/docker/app/internal/packager"
-	"github.com/docker/app/internal/types"
 	"github.com/docker/app/internal/validator"
+	"github.com/docker/app/types"
 	"github.com/docker/cli/cli"
 	cliopts "github.com/docker/cli/opts"
 	"github.com/spf13/cobra"

e2e/commands_test.go

@@ -1,8 +1,6 @@
 package e2e
 
 import (
-	"crypto/rand"
-	"encoding/hex"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -86,15 +84,6 @@ func TestRenderBinary(t *testing.T) {
 	}
 }
 
-func randomName(prefix string) string {
-	b := make([]byte, 16)
-	_, err := rand.Read(b)
-	if err != nil {
-		panic(err)
-	}
-	return prefix + hex.EncodeToString(b)
-}
-
 func TestInitBinary(t *testing.T) {
 	getDockerAppBinary(t)
 	composeData := `version: "3.2"
@@ -119,11 +108,11 @@ maintainers:
     email: joe@joe.com
 `
 	envData := "# some comment\nNGINX_VERSION=latest"
-	inputDir := randomName("app_input_")
-	os.Mkdir(inputDir, 0755)
-	ioutil.WriteFile(filepath.Join(inputDir, internal.ComposeFileName), []byte(composeData), 0644)
-	ioutil.WriteFile(filepath.Join(inputDir, ".env"), []byte(envData), 0644)
-	defer os.RemoveAll(inputDir)
+	dir := fs.NewDir(t, "app_input",
+		fs.WithFile(internal.ComposeFileName, composeData),
+		fs.WithFile(".env", envData),
+	)
+	defer dir.Remove()
 
 	testAppName := "app-test"
 	dirName := internal.DirNameFromAppName(testAppName)
@@ -133,7 +122,7 @@ maintainers:
 		"init",
 		testAppName,
 		"-c",
-		filepath.Join(inputDir, internal.ComposeFileName),
+		dir.Join(internal.ComposeFileName),
 		"-d",
 		"my cool app",
 		"-m", "bob",
@@ -157,7 +146,7 @@ maintainers:
 		"init",
 		"tac",
 		"-c",
-		filepath.Join(inputDir, internal.ComposeFileName),
+		dir.Join(internal.ComposeFileName),
 		"-d",
 		"my cool app",
 		"-m", "bob",
@@ -166,7 +155,8 @@ maintainers:
 	}
 	assertCommand(t, dockerApp, args...)
 	defer os.Remove("tac.dockerapp")
-	appData, _ := ioutil.ReadFile("tac.dockerapp")
+	appData, err := ioutil.ReadFile("tac.dockerapp")
+	assert.NilError(t, err)
 	golden.Assert(t, string(appData), "init-singlefile.dockerapp")
 	// Check various commands work on single-file app package
 	assertCommand(t, dockerApp, "inspect", "tac")
@@ -179,11 +169,11 @@ func TestDetectAppBinary(t *testing.T) {
 	assertCommand(t, dockerApp, "inspect")
 	cwd, err := os.Getwd()
 	assert.NilError(t, err)
+	assert.NilError(t, os.Chdir("helm.dockerapp"))
 	defer os.Chdir(cwd)
-	os.Chdir("helm.dockerapp")
 	assertCommand(t, dockerApp, "inspect")
 	assertCommand(t, dockerApp, "inspect", ".")
-	os.Chdir(filepath.Join(cwd, "render"))
+	assert.NilError(t, os.Chdir(filepath.Join(cwd, "render")))
 	assertCommandFailureOutput(t, "inspect-multiple-apps.golden", dockerApp, "inspect")
 }
 
@@ -206,17 +196,17 @@ func TestPackBinary(t *testing.T) {
 	assert.Assert(t, strings.Contains(result.Stdout(), "nginx"))
 	cwd, err := os.Getwd()
 	assert.NilError(t, err)
-	os.Chdir(tempDir)
+	assert.NilError(t, os.Chdir(tempDir))
+	defer os.Chdir(cwd)
 	result = icmd.RunCommand(dockerApp, "helm", "test")
 	result.Assert(t, icmd.Success)
 	_, err = os.Stat("test.chart/Chart.yaml")
 	assert.NilError(t, err)
-	os.Mkdir("output", 0755)
+	assert.NilError(t, os.Mkdir("output", 0755))
 	result = icmd.RunCommand(dockerApp, "unpack", "test", "-o", "output")
 	result.Assert(t, icmd.Success)
 	_, err = os.Stat("output/test.dockerapp/docker-compose.yml")
 	assert.NilError(t, err)
-	os.Chdir(cwd)
 }
 
 func runHelmCommand(t *testing.T, args ...string) *fs.Dir {

internal/compose/compose.go

@@ -0,0 +1,37 @@
+package compose
+
+import (
+	"regexp"
+
+	"github.com/docker/cli/cli/compose/loader"
+	"github.com/docker/cli/cli/compose/template"
+	composetypes "github.com/docker/cli/cli/compose/types"
+	"github.com/pkg/errors"
+)
+
+// Load applies the specified function when loading a slice of compose data
+func Load(composes [][]byte, apply func(string) (string, error)) ([]composetypes.ConfigFile, error) {
+	configFiles := []composetypes.ConfigFile{}
+	for _, data := range composes {
+		s, err := apply(string(data))
+		if err != nil {
+			return nil, err
+		}
+		parsed, err := loader.ParseYAML([]byte(s))
+		if err != nil {
+			return nil, errors.Wrapf(err, "failed to parse Compose file %s", data)
+		}
+		configFiles = append(configFiles, composetypes.ConfigFile{Config: parsed})
+	}
+	return configFiles, nil
+}
+
+// ExtractVariables extracts the variables from the specified compose data
+// This is a small helper to docker/cli template.ExtractVariables function
+func ExtractVariables(data []byte, pattern *regexp.Regexp) (map[string]string, error) {
+	cfgMap, err := loader.ParseYAML(data)
+	if err != nil {
+		return nil, err
+	}
+	return template.ExtractVariables(cfgMap, pattern), nil
+}

internal/helm/helm.go

@@ -11,16 +11,16 @@ import (
 	yaml "gopkg.in/yaml.v2"
 
 	"github.com/docker/app/internal"
+	"github.com/docker/app/internal/compose"
 	"github.com/docker/app/internal/helm/templateconversion"
 	"github.com/docker/app/internal/helm/templateloader"
 	"github.com/docker/app/internal/helm/templatev1beta2"
-	"github.com/docker/app/internal/render"
 	"github.com/docker/app/internal/settings"
 	"github.com/docker/app/internal/slices"
-	"github.com/docker/app/internal/types"
+	"github.com/docker/app/render"
+	"github.com/docker/app/types"
 	"github.com/docker/cli/cli/command/stack/kubernetes"
 	"github.com/docker/cli/cli/compose/loader"
-	"github.com/docker/cli/cli/compose/template"
 	"github.com/docker/cli/kubernetes/compose/v1beta1"
 	"github.com/docker/cli/kubernetes/compose/v1beta2"
 	"github.com/pkg/errors"
@@ -44,51 +44,47 @@ with the appropriate content (value or template)
 */
 
 // Helm renders an app as an Helm Chart
-func Helm(app types.App, env map[string]string, shouldRender bool, stackVersion string) error {
-	targetDir := internal.AppNameFromDir(app.Path) + ".chart"
+func Helm(app *types.App, env map[string]string, shouldRender bool, stackVersion string) error {
+	targetDir := internal.AppNameFromDir(app.Name) + ".chart"
 	if err := os.MkdirAll(targetDir, 0755); err != nil {
 		return errors.Wrap(err, "failed to create Chart directory")
 	}
-	err := makeChart(app.Path, targetDir)
+	err := makeChart(app.Metadata(), targetDir)
 	if err != nil {
 		return err
 	}
 	if shouldRender {
 		return helmRender(app, targetDir, env, stackVersion)
 	}
-	// FIXME(vdemeester) handle that
-	data, err := ioutil.ReadFile(filepath.Join(app.Path, internal.ComposeFileName))
-	if err != nil {
-		return errors.Wrap(err, "failed to read application Compose file")
+	// FIXME(vdemeester) support multiple file for helm
+	if len(app.Composes()) > 1 {
+		return errors.New("helm rendering doesn't support multiple composefiles")
 	}
-	cfgMap, err := loader.ParseYAML(data)
-	if err != nil {
-		return errors.Wrap(err, "failed to parse compose file")
-	}
-	vars := template.ExtractVariables(cfgMap, render.Pattern)
+	data := app.Composes()[0]
 	// FIXME(vdemeester): remove the need to create this slice
 	variables := []string{}
+	vars, err := compose.ExtractVariables(data, render.Pattern)
+	if err != nil {
+		return err
+	}
 	for k := range vars {
 		variables = append(variables, k)
 	}
-	err = makeStack(app.Path, targetDir, data, stackVersion)
+	err = makeStack(app.Name, targetDir, data, stackVersion)
 	if err != nil {
 		return err
 	}
-	return makeValues(app.Path, targetDir, app.SettingsFiles, env, variables)
+	return makeValues(app, targetDir, env, variables)
 }
 
 // makeValues updates helm values.yaml with used variables from settings and env
-func makeValues(appname, targetDir string, settingsFile []string, env map[string]string, variables []string) error {
+func makeValues(app *types.App, targetDir string, env map[string]string, variables []string) error {
 	// merge our variables into Values.yaml
-	sf := []string{filepath.Join(appname, internal.SettingsFileName)}
-	sf = append(sf, settingsFile...)
-	s, err := settings.LoadFiles(sf)
+	s, err := settings.LoadMultiple(app.Settings())
 	if err != nil {
 		return err
 	}
-	metaFile := filepath.Join(appname, internal.MetadataFileName)
-	metaPrefixed, err := settings.LoadFile(metaFile, settings.WithPrefix("app"))
+	metaPrefixed, err := settings.Load(app.Metadata(), settings.WithPrefix("app"))
 	if err != nil {
 		return err
 	}
@@ -174,7 +170,7 @@ func makeStack(appname string, targetDir string, data []byte, stackVersion strin
 	return ioutil.WriteFile(filepath.Join(targetDir, "templates", "stack.yaml"), stackData, 0644)
 }
 
-func helmRender(app types.App, targetDir string, env map[string]string, stackVersion string) error {
+func helmRender(app *types.App, targetDir string, env map[string]string, stackVersion string) error {
 	rendered, err := render.Render(app, env)
 	if err != nil {
 		return err
@@ -214,14 +210,9 @@ func helmRender(app types.App, targetDir string, env map[string]string, stackVer
 	return ioutil.WriteFile(filepath.Join(targetDir, "templates", "stack.yaml"), stackData, 0644)
 }
 
-func makeChart(appname, targetDir string) error {
-	metaFile := filepath.Join(appname, internal.MetadataFileName)
-	metaContent, err := ioutil.ReadFile(metaFile)
-	if err != nil {
-		return errors.Wrap(err, "failed to read application metadata")
-	}
+func makeChart(metadata []byte, targetDir string) error {
 	var meta types.AppMetadata
-	err = yaml.Unmarshal(metaContent, &meta)
+	err := yaml.Unmarshal(metadata, &meta)
 	if err != nil {
 		return errors.Wrap(err, "failed to parse application metadata")
 	}

internal/inspect/inspect.go

@@ -1,35 +1,26 @@
-package render
+package inspect
 
 import (
 	"fmt"
 	"io"
-	"io/ioutil"
-	"path/filepath"
 	"sort"
 	"text/tabwriter"
 
-	"github.com/docker/app/internal"
 	"github.com/docker/app/internal/settings"
-	"github.com/docker/app/internal/types"
+	"github.com/docker/app/types"
 	"github.com/pkg/errors"
 	yaml "gopkg.in/yaml.v2"
 )
 
 // Inspect dumps the metadata of an app
-func Inspect(out io.Writer, appname string) error {
-	metaFile := filepath.Join(appname, internal.MetadataFileName)
-	metaContent, err := ioutil.ReadFile(metaFile)
-	if err != nil {
-		return errors.Wrap(err, "failed to read application metadata")
-	}
+func Inspect(out io.Writer, app *types.App) error {
 	var meta types.AppMetadata
-	err = yaml.Unmarshal(metaContent, &meta)
+	err := yaml.Unmarshal(app.Metadata(), &meta)
 	if err != nil {
 		return errors.Wrap(err, "failed to parse application metadata")
 	}
 	// extract settings
-	settingsFile := filepath.Join(appname, internal.SettingsFileName)
-	s, err := settings.LoadFile(settingsFile)
+	s, err := settings.LoadMultiple(app.Settings())
 	if err != nil {
 		return errors.Wrap(err, "failed to load application settings")
 	}

internal/inspect/inspect_test.go

@@ -1,4 +1,4 @@
-package render
+package inspect
 
 import (
 	"bytes"
@@ -7,6 +7,7 @@ import (
 	"testing"
 
 	"github.com/docker/app/internal"
+	"github.com/docker/app/types"
 
 	"gotest.tools/assert"
 	is "gotest.tools/assert/cmp"
@@ -14,16 +15,23 @@ import (
 	"gotest.tools/golden"
 )
 
+const (
+	composeYAML = `version: "3.1"
+
+services:
+  web:
+    image: nginx`
+)
+
 func TestInspectErrorsOnFiles(t *testing.T) {
 	dir := fs.NewDir(t, "inspect-errors",
-		fs.WithDir("empty-app"),
 		fs.WithDir("unparseable-metadata-app",
+			fs.WithFile(internal.ComposeFileName, composeYAML),
 			fs.WithFile(internal.MetadataFileName, `something is wrong`),
-		),
-		fs.WithDir("no-settings-app",
-			fs.WithFile(internal.MetadataFileName, `{}`),
+			fs.WithFile(internal.SettingsFileName, "foo"),
 		),
 		fs.WithDir("unparseable-settings-app",
+			fs.WithFile(internal.ComposeFileName, composeYAML),
 			fs.WithFile(internal.MetadataFileName, `{}`),
 			fs.WithFile(internal.SettingsFileName, "foo"),
 		),
@@ -31,13 +39,12 @@ func TestInspectErrorsOnFiles(t *testing.T) {
 	defer dir.Remove()
 
 	for appname, expectedError := range map[string]string{
-		"inexistent-app":           "failed to read application metadata",
-		"empty-app":                "failed to read application metadata",
 		"unparseable-metadata-app": "failed to parse application metadat",
-		"no-settings-app":          "failed to load application settings",
 		"unparseable-settings-app": "failed to load application settings",
 	} {
-		err := Inspect(ioutil.Discard, dir.Join(appname))
+		app, err := types.NewAppFromDefaultFiles(dir.Join(appname))
+		assert.NilError(t, err)
+		err = Inspect(ioutil.Discard, app)
 		assert.Check(t, is.ErrorContains(err, expectedError))
 	}
 }
@@ -45,12 +52,14 @@ func TestInspectErrorsOnFiles(t *testing.T) {
 func TestInspect(t *testing.T) {
 	dir := fs.NewDir(t, "inspect",
 		fs.WithDir("no-maintainers",
+			fs.WithFile(internal.ComposeFileName, composeYAML),
 			fs.WithFile(internal.MetadataFileName, `
 version: 0.1.0
 name: foo`),
 			fs.WithFile(internal.SettingsFileName, ``),
 		),
 		fs.WithDir("no-description",
+			fs.WithFile(internal.ComposeFileName, composeYAML),
 			fs.WithFile(internal.MetadataFileName, `
 version: 0.1.0
 name: foo
@@ -60,6 +69,7 @@ maintainers:
 			fs.WithFile(internal.SettingsFileName, ""),
 		),
 		fs.WithDir("no-settings",
+			fs.WithFile(internal.ComposeFileName, composeYAML),
 			fs.WithFile(internal.MetadataFileName, `
 version: 0.1.0
 name: foo
@@ -70,6 +80,7 @@ description: "this is sparta !"`),
 			fs.WithFile(internal.SettingsFileName, ""),
 		),
 		fs.WithDir("full",
+			fs.WithFile(internal.ComposeFileName, composeYAML),
 			fs.WithFile(internal.MetadataFileName, `
 version: 0.1.0
 name: foo
@@ -88,8 +99,10 @@ text: hello`),
 		"no-maintainers", "no-description", "no-settings", "full",
 	} {
 		outBuffer := new(bytes.Buffer)
-		err := Inspect(outBuffer, dir.Join(appname))
+		app, err := types.NewAppFromDefaultFiles(dir.Join(appname))
 		assert.NilError(t, err)
-		golden.Assert(t, outBuffer.String(), fmt.Sprintf("inspect-%s.golden", appname))
+		err = Inspect(outBuffer, app)
+		assert.NilError(t, err)
+		golden.Assert(t, outBuffer.String(), fmt.Sprintf("inspect-%s.golden", appname), appname)
 	}
 }

internal/packager/extract.go

@@ -1,9 +1,7 @@
 package packager
 
 import (
-	"archive/tar"
 	"fmt"
-	"io"
 	"io/ioutil"
 	"os"
 	"os/exec"
@@ -11,14 +9,11 @@ import (
 	"strings"
 
 	"github.com/docker/app/internal"
-	"github.com/docker/app/internal/types"
+	"github.com/docker/app/loader"
+	"github.com/docker/app/types"
 	"github.com/pkg/errors"
 )
 
-var (
-	noop = func() {}
-)
-
 // findApp looks for an app in CWD or subdirs
 func findApp() (string, error) {
 	cwd, err := os.Getwd()
@@ -48,7 +43,7 @@ func findApp() (string, error) {
 }
 
 // extractImage extracts a docker application in a docker image to a temporary directory
-func extractImage(appname string) (types.App, error) {
+func extractImage(appname string, ops ...func(*types.App) error) (*types.App, error) {
 	var imagename string
 	if strings.Contains(appname, ":") {
 		nametag := strings.Split(appname, ":")
@@ -66,161 +61,67 @@ func extractImage(appname string) (types.App, error) {
 	}
 	tempDir, err := ioutil.TempDir("", "dockerapp")
 	if err != nil {
-		return types.App{}, errors.Wrap(err, "failed to create temporary directory")
+		return nil, errors.Wrap(err, "failed to create temporary directory")
 	}
 	defer os.RemoveAll(tempDir)
 	err = Load(imagename, tempDir)
 	if err != nil {
 		if !strings.Contains(imagename, "/") {
-			return types.App{}, fmt.Errorf("could not locate application in either filesystem or docker image")
+			return nil, fmt.Errorf("could not locate application in either filesystem or docker image")
 		}
 		// Try to pull it
 		cmd := exec.Command("docker", "pull", imagename)
+		cmd.Stderr = os.Stderr
+		cmd.Stdout = os.Stdout
 		if err := cmd.Run(); err != nil {
-			return types.App{}, fmt.Errorf("could not locate application in filesystem, docker image or registry")
+			return nil, fmt.Errorf("could not locate application in filesystem, docker image or registry")
 		}
 		if err := Load(imagename, tempDir); err != nil {
-			return types.App{}, errors.Wrap(err, "failed to load pulled image")
+			return nil, errors.Wrap(err, "failed to load pulled image")
 		}
 	}
-	// this gave us a compressed app, run through extract again
-	app, err := Extract(filepath.Join(tempDir, appname))
-	return types.App{
-		Path:    app.Path,
-		Cleanup: app.Cleanup,
-	}, err
+	return loader.LoadFromTar(filepath.Join(tempDir, appname), ops...)
 }
 
 // Extract extracts the app content if argument is an archive, or does nothing if a dir.
 // It returns source file, effective app name, and cleanup function
 // If appname is empty, it looks into cwd, and all subdirs for a single matching .dockerapp
 // If nothing is found, it looks for an image and loads it
-func Extract(appname string, ops ...func(*types.App)) (types.App, error) {
-	if appname == "" {
+func Extract(name string, ops ...func(*types.App) error) (*types.App, error) {
+	if name == "" {
 		var err error
-		if appname, err = findApp(); err != nil {
-			return types.App{}, err
+		if name, err = findApp(); err != nil {
+			return nil, err
 		}
 	}
-	if appname == "." {
+	if name == "." {
 		var err error
-		if appname, err = os.Getwd(); err != nil {
-			return types.App{}, errors.Wrap(err, "cannot resolve current working directory")
+		if name, err = os.Getwd(); err != nil {
+			return nil, errors.Wrap(err, "cannot resolve current working directory")
 		}
 	}
-	originalAppname := appname
-	appname = filepath.Clean(appname)
-	// try appending our extension
-	appname = internal.DirNameFromAppName(appname)
+	ops = append(ops, types.WithName(name))
+	appname := internal.DirNameFromAppName(name)
 	s, err := os.Stat(appname)
-	if err != nil {
-		// try verbatim
-		s, err = os.Stat(originalAppname)
-	}
 	if err != nil {
 		// look for a docker image
-		return extractImage(originalAppname)
+		return extractImage(name, ops...)
 	}
 	if s.IsDir() {
 		// directory: already decompressed
-		ops = append([]func(*types.App){
-			types.WithOriginalPath(appname),
-			types.WithCleanup(noop),
-		}, ops...)
-		return types.NewApp(appname, ops...), nil
+		appOpts := append(ops,
+			types.WithPath(appname),
+		)
+		return loader.LoadFromDirectory(appname, appOpts...)
 	}
 	// not a dir: single-file or a tarball package, extract that in a temp dir
-	tempDir, err := ioutil.TempDir("", "dockerapp")
+	app, err := loader.LoadFromTar(appname, ops...)
 	if err != nil {
-		return types.App{}, errors.Wrap(err, "failed to create temporary directory")
-	}
-	defer func() {
+		f, err := os.Open(appname)
 		if err != nil {
-			os.RemoveAll(tempDir)
+			return nil, err
 		}
-	}()
-	appDir := filepath.Join(tempDir, filepath.Base(appname))
-	if err = os.Mkdir(appDir, 0755); err != nil {
-		return types.App{}, errors.Wrap(err, "failed to create application in temporary directory")
+		return loader.LoadFromSingleFile(appname, f, ops...)
 	}
-	if err = extract(appname, appDir); err == nil {
-		ops = append([]func(*types.App){
-			types.WithOriginalPath(appname),
-			types.WithCleanup(func() { os.RemoveAll(tempDir) }),
-		}, ops...)
-		return types.NewApp(appDir, ops...), nil
-	}
-	if err = extractSingleFile(appname, appDir); err != nil {
-		return types.App{}, err
-	}
-	// not a tarball, single-file then
-	ops = append([]func(*types.App){
-		types.WithOriginalPath(appname),
-		types.WithCleanup(func() { os.RemoveAll(tempDir) }),
-	}, ops...)
-	return types.NewApp(appDir, ops...), nil
-}
-
-func extractSingleFile(appname, appDir string) error {
-	// not a tarball, single-file then
-	data, err := ioutil.ReadFile(appname)
-	if err != nil {
-		return errors.Wrap(err, "failed to read single-file application package")
-	}
-	parts := strings.Split(string(data), "\n---")
-	if len(parts) != 3 {
-		return fmt.Errorf("malformed single-file application: expected 3 documents")
-	}
-	for i, p := range parts {
-		data := ""
-		if i == 0 {
-			data = p
-		} else {
-			d := strings.SplitN(p, "\n", 2)
-			if len(d) > 1 {
-				data = d[1]
-			}
-		}
-		err = ioutil.WriteFile(filepath.Join(appDir, internal.FileNames[i]), []byte(data), 0644)
-		if err != nil {
-			return errors.Wrap(err, "failed to write application file")
-		}
-	}
-	return nil
-}
-
-func extract(appname, outputDir string) error {
-	f, err := os.Open(appname)
-	if err != nil {
-		return errors.Wrap(err, "failed to open application package")
-	}
-	defer f.Close()
-	tarReader := tar.NewReader(f)
-	outputDir = outputDir + "/"
-	for {
-		header, err := tarReader.Next()
-		if err == io.EOF {
-			break
-		}
-		if err != nil {
-			return errors.Wrap(err, "error reading from tar header")
-		}
-		switch header.Typeflag {
-		case tar.TypeDir: // = directory
-			if err := os.Mkdir(outputDir+header.Name, 0755); err != nil {
-				return err
-			}
-		case tar.TypeReg: // = regular file
-			data := make([]byte, header.Size)
-			_, err := tarReader.Read(data)
-			if err != nil && err != io.EOF {
-				return errors.Wrap(err, "error reading from tar data")
-			}
-			err = ioutil.WriteFile(outputDir+header.Name, data, 0644)
-			if err != nil {
-				return errors.Wrap(err, "error writing output file")
-			}
-		}
-	}
-	return nil
+	return app, nil
 }

internal/packager/init.go

@@ -12,11 +12,12 @@ import (
 	"text/template"
 
 	"github.com/docker/app/internal"
-	"github.com/docker/app/internal/render"
-	"github.com/docker/app/internal/types"
-	"github.com/docker/cli/cli/compose/loader"
+	"github.com/docker/app/internal/compose"
+	"github.com/docker/app/loader"
+	"github.com/docker/app/render"
+	"github.com/docker/app/types"
+	composeloader "github.com/docker/cli/cli/compose/loader"
 	"github.com/docker/cli/cli/compose/schema"
-	dtemplate "github.com/docker/cli/cli/compose/template"
 	"github.com/docker/cli/opts"
 	"github.com/pkg/errors"
 	log "github.com/sirupsen/logrus"
@@ -89,7 +90,11 @@ func Init(name string, composeFile string, description string, maintainers []str
 		return err
 	}
 	defer target.(io.WriteCloser).Close()
-	return Merge(temp, target)
+	app, err := loader.LoadFromDirectory(temp)
+	if err != nil {
+		return err
+	}
+	return Merge(app, target)
 }
 
 func initFromScratch(name string) error {
@@ -124,7 +129,7 @@ func initFromComposeFile(name string, composeFile string) error {
 	if err != nil {
 		return errors.Wrap(err, "failed to read compose file")
 	}
-	cfgMap, err := loader.ParseYAML(composeRaw)
+	cfgMap, err := composeloader.ParseYAML(composeRaw)
 	if err != nil {
 		return errors.Wrap(err, "failed to parse compose file")
 	}
@@ -141,7 +146,10 @@ func initFromComposeFile(name string, composeFile string) error {
 			}
 		}
 	}
-	vars := dtemplate.ExtractVariables(cfgMap, render.Pattern)
+	vars, err := compose.ExtractVariables(composeRaw, render.Pattern)
+	if err != nil {
+		return errors.Wrap(err, "failed to parse compose file")
+	}
 	needsFilling := false
 	for k, v := range vars {
 		if _, ok := settings[k]; !ok {

internal/packager/packing.go

@@ -9,6 +9,7 @@ import (
 	"path/filepath"
 
 	"github.com/docker/app/internal"
+	"github.com/docker/docker/pkg/archive"
 )
 
 func tarAdd(tarout *tar.Writer, path, file string) error {
@@ -87,5 +88,11 @@ func Unpack(appname, targetDir string) error {
 	if err != nil {
 		return err
 	}
-	return extract(appname, out)
+	f, err := os.Open(appname)
+	if err != nil {
+		return err
+	}
+	return archive.Untar(f, out, &archive.TarOptions{
+		NoLchown: true,
+	})
 }

internal/packager/registry.go

@@ -12,26 +12,16 @@ import (
 	"strings"
 
 	"github.com/docker/app/internal"
-	"github.com/docker/app/internal/types"
+	"github.com/docker/app/types"
 	"github.com/docker/distribution/reference"
 	"github.com/pkg/errors"
 	yaml "gopkg.in/yaml.v2"
 )
 
 // Save saves an app to docker and returns the image name.
-func Save(appname, namespace, tag string) (string, error) {
-	app, err := Extract(appname)
-	if err != nil {
-		return "", err
-	}
-	defer app.Cleanup()
-	metaFile := filepath.Join(app.Path, internal.MetadataFileName)
-	metaContent, err := ioutil.ReadFile(metaFile)
-	if err != nil {
-		return "", errors.Wrap(err, "failed to read application metadata")
-	}
+func Save(app *types.App, namespace, tag string) (string, error) {
 	var meta types.AppMetadata
-	err = yaml.Unmarshal(metaContent, &meta)
+	err := yaml.Unmarshal(app.Metadata(), &meta)
 	if err != nil {
 		return "", errors.Wrap(err, "failed to parse application metadata")
 	}
@@ -60,7 +50,7 @@ COPY / /
 		return "", errors.Wrapf(err, "cannot create file %s", di)
 	}
 	defer os.Remove(di)
-	imageName := namespace + internal.AppNameFromDir(app.Path) + internal.AppExtension + ":" + tag
+	imageName := namespace + internal.AppNameFromDir(app.Name) + internal.AppExtension + ":" + tag
 	args := []string{"build", "-t", imageName, "-f", df, app.Path}
 	cmd := exec.Command("docker", args...)
 	cmd.Stdout = ioutil.Discard
@@ -111,13 +101,8 @@ func Load(repotag string, outputDir string) error {
 }
 
 // Push pushes an app to a registry
-func Push(appname, namespace, tag string) error {
-	app, err := Extract(appname)
-	if err != nil {
-		return err
-	}
-	defer app.Cleanup()
-	imageName, err := Save(app.Path, namespace, tag)
+func Push(app *types.App, namespace, tag string) error {
+	imageName, err := Save(app, namespace, tag)
 	if err != nil {
 		return err
 	}

internal/packager/split.go

@@ -7,21 +7,28 @@ import (
 	"path/filepath"
 
 	"github.com/docker/app/internal"
+	"github.com/docker/app/types"
+	"github.com/pkg/errors"
 )
 
 // Split converts an app package to the split version
-func Split(appname string, outputDir string) error {
-	err := os.Mkdir(outputDir, 0755)
+func Split(app *types.App, outputDir string) error {
+	if len(app.Composes()) > 1 {
+		return errors.New("split: multiple compose files is not supported")
+	}
+	if len(app.Settings()) > 1 {
+		return errors.New("split: multiple setting files is not supported")
+	}
+	err := os.MkdirAll(outputDir, 0755)
 	if err != nil {
 		return err
 	}
-	for _, n := range internal.FileNames {
-		input, err := ioutil.ReadFile(filepath.Join(appname, n))
-		if err != nil {
-			return err
-		}
-		err = ioutil.WriteFile(filepath.Join(outputDir, n), input, 0644)
-		if err != nil {
+	for file, data := range map[string][]byte{
+		internal.MetadataFileName: app.Metadata(),
+		internal.ComposeFileName:  app.Composes()[0],
+		internal.SettingsFileName: app.Settings()[0],
+	} {
+		if err := ioutil.WriteFile(filepath.Join(outputDir, file), data, 0644); err != nil {
 			return err
 		}
 	}
@@ -29,20 +36,23 @@ func Split(appname string, outputDir string) error {
 }
 
 // Merge converts an app-package to the single-file merged version
-func Merge(appname string, target io.Writer) error {
-	for i, n := range internal.FileNames {
-		input, err := ioutil.ReadFile(filepath.Join(appname, n))
-		if err != nil {
+func Merge(app *types.App, target io.Writer) error {
+	if len(app.Composes()) > 1 {
+		return errors.New("merge: multiple compose files is not supported")
+	}
+	if len(app.Settings()) > 1 {
+		return errors.New("merge: multiple setting files is not supported")
+	}
+	for _, data := range [][]byte{
+		app.Metadata(),
+		[]byte(types.SingleFileSeparator),
+		app.Composes()[0],
+		[]byte(types.SingleFileSeparator),
+		app.Settings()[0],
+	} {
+		if _, err := target.Write(data); err != nil {
 			return err
 		}
-		if _, err := target.Write(input); err != nil {
-			return err
-		}
-		if i != 2 {
-			if _, err := io.WriteString(target, "\n---\n"); err != nil {
-				return err
-			}
-		}
 	}
 	return nil
 }

internal/settings/load.go

@@ -1,21 +1,23 @@
 package settings
 
 import (
+	"bytes"
 	"fmt"
 	"io"
-	"os"
+	"io/ioutil"
 
 	"github.com/pkg/errors"
 	yaml "gopkg.in/yaml.v2"
 )
 
-// Load loads the given reader in settings
-func Load(r io.Reader, ops ...func(*Options)) (Settings, error) {
+// Load loads the given data in settings
+func Load(data []byte, ops ...func(*Options)) (Settings, error) {
 	options := &Options{}
 	for _, op := range ops {
 		op(options)
 	}
 
+	r := bytes.NewReader(data)
 	s := make(map[interface{}]interface{})
 	decoder := yaml.NewDecoder(r)
 	if err := decoder.Decode(&s); err != nil {
@@ -37,13 +39,29 @@ func Load(r io.Reader, ops ...func(*Options)) (Settings, error) {
 	return settings, nil
 }
 
+// LoadMultiple loads multiple data in settings
+func LoadMultiple(datas [][]byte, ops ...func(*Options)) (Settings, error) {
+	m := Settings(map[string]interface{}{})
+	for _, data := range datas {
+		settings, err := Load(data, ops...)
+		if err != nil {
+			return nil, err
+		}
+		m, err = Merge(m, settings)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return m, nil
+}
+
 // LoadFile loads a file (path) in settings (i.e. flatten map)
 func LoadFile(path string, ops ...func(*Options)) (Settings, error) {
-	r, err := os.Open(path)
+	data, err := ioutil.ReadFile(path)
 	if err != nil {
 		return nil, err
 	}
-	return Load(r, ops...)
+	return Load(data, ops...)
 }
 
 // LoadFiles loads multiple path in settings, merging them.

internal/settings/load_test.go

@@ -1,7 +1,6 @@
 package settings
 
 import (
-	"strings"
 	"testing"
 
 	"gotest.tools/assert"
@@ -10,15 +9,15 @@ import (
 )
 
 func TestLoadErrors(t *testing.T) {
-	_, err := Load(strings.NewReader("invalid yaml"))
+	_, err := Load([]byte("invalid yaml"))
 	assert.Check(t, is.ErrorContains(err, "failed to read settings"))
 
-	_, err = Load(strings.NewReader(`
+	_, err = Load([]byte(`
 foo: bar
 1: baz`))
 	assert.Check(t, is.ErrorContains(err, "Non-string key at top level: 1"))
 
-	_, err = Load(strings.NewReader(`
+	_, err = Load([]byte(`
 foo:
   bar: baz
   1: banana`))
@@ -26,7 +25,7 @@ foo:
 }
 
 func TestLoad(t *testing.T) {
-	settings, err := Load(strings.NewReader(`
+	settings, err := Load([]byte(`
 foo: bar
 bar:
   baz: banana
@@ -45,7 +44,7 @@ baz:
 }
 
 func TestLoadWithPrefix(t *testing.T) {
-	settings, err := Load(strings.NewReader(`
+	settings, err := Load([]byte(`
 foo: bar
 bar: baz
 `), WithPrefix("p"))
@@ -78,3 +77,25 @@ bar:
 		"bar.port": "10",
 	}))
 }
+
+func TestLoadMultiples(t *testing.T) {
+	datas := [][]byte{
+		[]byte(`
+foo: bar
+bar:
+  baz: banana
+  port: 80`),
+		[]byte(`
+foo: baz
+bar:
+  port: 10`),
+	}
+
+	settings, err := LoadMultiple(datas)
+	assert.NilError(t, err)
+	assert.Check(t, is.DeepEqual(settings.Flatten(), map[string]string{
+		"foo":      "baz",
+		"bar.baz":  "banana",
+		"bar.port": "10",
+	}))
+}

internal/types/types.go

@@ -1,61 +0,0 @@
-package types
-
-import (
-	"path/filepath"
-
-	"github.com/docker/app/internal"
-)
-
-// App represents an app (extracted or not)
-type App struct {
-	Path          string
-	OriginalPath  string
-	ComposeFiles  []string
-	SettingsFiles []string
-	MetadataFile  string
-	Cleanup       func()
-}
-
-// NewApp creates a new docker app with the specified path and struct modifiers
-func NewApp(path string, ops ...func(*App)) App {
-	app := &App{
-		Path:          path,
-		ComposeFiles:  []string{filepath.Join(path, internal.ComposeFileName)},
-		SettingsFiles: []string{filepath.Join(path, internal.SettingsFileName)},
-		MetadataFile:  filepath.Join(path, internal.MetadataFileName),
-	}
-
-	for _, op := range ops {
-		op(app)
-	}
-
-	return *app
-}
-
-// WithOriginalPath sets the original path of the app
-func WithOriginalPath(path string) func(*App) {
-	return func(app *App) {
-		app.OriginalPath = path
-	}
-}
-
-// WithCleanup sets the cleanup function of the app
-func WithCleanup(f func()) func(*App) {
-	return func(app *App) {
-		app.Cleanup = f
-	}
-}
-
-// WithSettingsFiles adds the specified settings files of the app
-func WithSettingsFiles(files ...string) func(*App) {
-	return func(app *App) {
-		app.SettingsFiles = append(app.SettingsFiles, files...)
-	}
-}
-
-// WithComposeFiles adds the specified compose files of the app
-func WithComposeFiles(files ...string) func(*App) {
-	return func(app *App) {
-		app.ComposeFiles = append(app.ComposeFiles, files...)
-	}
-}

internal/validator/validate.go

@@ -3,25 +3,19 @@ package validator
 import (
 	"errors"
 	"fmt"
-	"io/ioutil"
-	"os"
-	"path/filepath"
 	"strings"
 
 	"github.com/docker/app/internal"
-	"github.com/docker/app/internal/render"
-	"github.com/docker/app/internal/types"
+	"github.com/docker/app/render"
 	"github.com/docker/app/specification"
+	"github.com/docker/app/types"
 	"github.com/docker/cli/cli/compose/loader"
 )
 
 // Validate checks an application definition meets the specifications (metadata and rendered compose file)
-func Validate(app types.App, env map[string]string) error {
+func Validate(app *types.App, env map[string]string) error {
 	var errs []string
-	if err := checkExistingFiles(app.Path); err != nil {
-		errs = append(errs, err.Error())
-	}
-	if err := validateMetadata(app.Path); err != nil {
+	if err := validateMetadata(app.Metadata()); err != nil {
 		errs = append(errs, err.Error())
 	}
 	if _, err := render.Render(app, env); err != nil {
@@ -30,25 +24,7 @@ func Validate(app types.App, env map[string]string) error {
 	return concatenateErrors(errs)
 }
 
-func checkExistingFiles(appname string) error {
-	var errs []string
-	if _, err := os.Stat(filepath.Join(appname, internal.SettingsFileName)); err != nil {
-		errs = append(errs, "failed to read application settings")
-	}
-	if _, err := os.Stat(filepath.Join(appname, internal.MetadataFileName)); err != nil {
-		errs = append(errs, "failed to read application metadata")
-	}
-	if _, err := os.Stat(filepath.Join(appname, internal.ComposeFileName)); err != nil {
-		errs = append(errs, "failed to read application compose")
-	}
-	return concatenateErrors(errs)
-}
-
-func validateMetadata(appname string) error {
-	metadata, err := ioutil.ReadFile(filepath.Join(appname, internal.MetadataFileName))
-	if err != nil {
-		return fmt.Errorf("failed to read application metadata: %s", err)
-	}
+func validateMetadata(metadata []byte) error {
 	metadataYaml, err := loader.ParseYAML(metadata)
 	if err != nil {
 		return fmt.Errorf("failed to parse application metadata: %s", err)

internal/validator/validate_test.go

@@ -6,21 +6,10 @@ import (
 	"gotest.tools/assert"
 
 	"github.com/docker/app/internal"
-	"github.com/docker/app/internal/types"
+	"github.com/docker/app/types"
 	"gotest.tools/fs"
 )
 
-func TestValidateMissingFileApplication(t *testing.T) {
-	dir := fs.NewDir(t, t.Name(),
-		fs.WithDir("bad-app"),
-	)
-	defer dir.Remove()
-	errs := Validate(types.NewApp(dir.Join("bad-app")), nil)
-	assert.ErrorContains(t, errs, "failed to read application settings")
-	assert.ErrorContains(t, errs, "failed to read application metadata")
-	assert.ErrorContains(t, errs, "failed to read application compose")
-}
-
 func TestValidateBrokenMetadata(t *testing.T) {
 	brokenMetadata := `#version: 0.1.0-missing
 name: _INVALID-name
@@ -38,7 +27,9 @@ unknown: property`
 		fs.WithFile(internal.ComposeFileName, composeFile),
 		fs.WithFile(internal.SettingsFileName, ""))
 	defer dir.Remove()
-	err := Validate(types.NewApp(dir.Path()), nil)
+	app, err := types.NewAppFromDefaultFiles(dir.Path())
+	assert.NilError(t, err)
+	err = Validate(app, nil)
 	assert.Error(t, err, `failed to validate metadata:
 - maintainers.2.email: Does not match format 'email'
 - name: Does not match format 'hostname'
@@ -57,7 +48,9 @@ my-settings:
 		fs.WithFile(internal.ComposeFileName, composeFile),
 		fs.WithFile(internal.SettingsFileName, brokenSettings))
 	defer dir.Remove()
-	err := Validate(types.NewApp(dir.Path()), nil)
+	app, err := types.NewAppFromDefaultFiles(dir.Path())
+	assert.NilError(t, err)
+	err = Validate(app, nil)
 	assert.ErrorContains(t, err, `Non-string key in my-settings: 1`)
 }
 
@@ -72,7 +65,9 @@ unknown-property: value`
 		fs.WithFile(internal.ComposeFileName, brokenComposeFile),
 		fs.WithFile(internal.SettingsFileName, ""))
 	defer dir.Remove()
-	err := Validate(types.NewApp(dir.Path()), nil)
+	app, err := types.NewAppFromDefaultFiles(dir.Path())
+	assert.NilError(t, err)
+	err = Validate(app, nil)
 	assert.Error(t, err, "failed to load Compose file: unknown-property Additional property unknown-property is not allowed")
 }
 
@@ -90,6 +85,8 @@ services:
 		fs.WithFile(internal.ComposeFileName, composeFile),
 		fs.WithFile(internal.SettingsFileName, settings))
 	defer dir.Remove()
-	err := Validate(types.NewApp(dir.Path()), nil)
+	app, err := types.NewAppFromDefaultFiles(dir.Path())
+	assert.NilError(t, err)
+	err = Validate(app, nil)
 	assert.NilError(t, err)
 }

lib/lib.go

@@ -1,22 +0,0 @@
-package lib
-
-import (
-	"github.com/docker/app/internal/packager"
-	"github.com/docker/app/internal/render"
-	"github.com/docker/app/internal/types"
-	yaml "gopkg.in/yaml.v2"
-)
-
-// Render renders the application into a Compose file.
-func Render(appname string, settingsFiles []string, settings map[string]string) ([]byte, error) {
-	app, err := packager.Extract(appname, types.WithSettingsFiles(settingsFiles...))
-	if err != nil {
-		return nil, err
-	}
-	defer app.Cleanup()
-	rendered, err := render.Render(app, settings)
-	if err != nil {
-		return nil, err
-	}
-	return yaml.Marshal(rendered)
-}

loader/loader.go

@@ -0,0 +1,80 @@
+package loader
+
+import (
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/docker/app/internal"
+	"github.com/docker/app/types"
+	"github.com/docker/docker/pkg/archive"
+	"github.com/pkg/errors"
+)
+
+// LoadFromSingleFile loads a docker app from a single-file format (as a reader)
+func LoadFromSingleFile(path string, r io.Reader, ops ...func(*types.App) error) (*types.App, error) {
+	data, err := ioutil.ReadAll(r)
+	if err != nil {
+		return nil, errors.Wrap(err, "error reading single-file")
+	}
+	parts := strings.Split(string(data), types.SingleFileSeparator)
+	if len(parts) != 3 {
+		return nil, errors.Errorf("malformed single-file application: expected 3 documents, got %d", len(parts))
+	}
+	// 0. is metadata
+	metadata := strings.NewReader(parts[0])
+	// 1. is compose
+	compose := strings.NewReader(parts[1])
+	// 2. is settings
+	setting := strings.NewReader(parts[2])
+	appOps := append([]func(*types.App) error{
+		types.WithComposes(compose),
+		types.WithSettings(setting),
+		types.Metadata(metadata),
+	}, ops...)
+	return types.NewApp(path, appOps...)
+}
+
+// LoadFromDirectory loads a docker app from a directory
+func LoadFromDirectory(path string, ops ...func(*types.App) error) (*types.App, error) {
+	appOps := append([]func(*types.App) error{
+		types.MetadataFile(filepath.Join(path, internal.MetadataFileName)),
+		types.WithComposeFiles(filepath.Join(path, internal.ComposeFileName)),
+		types.WithSettingsFiles(filepath.Join(path, internal.SettingsFileName)),
+	}, ops...)
+	return types.NewApp(path, appOps...)
+}
+
+// LoadFromTar loads a docker app from a tarball
+func LoadFromTar(tar string, ops ...func(*types.App) error) (*types.App, error) {
+	f, err := os.Open(tar)
+	if err != nil {
+		return nil, errors.Wrap(err, "cannot load app from tar")
+	}
+	appOps := append(ops, types.WithPath(tar))
+	return LoadFromTarReader(f, appOps...)
+}
+
+// LoadFromTarReader loads a docker app from a tarball reader
+func LoadFromTarReader(r io.Reader, ops ...func(*types.App) error) (*types.App, error) {
+	dir, err := ioutil.TempDir("", "load-from-tar")
+	if err != nil {
+		return nil, errors.Wrap(err, "cannot load app from tar")
+	}
+	if err := archive.Untar(r, dir, &archive.TarOptions{
+		NoLchown: true,
+	}); err != nil {
+		if err := os.RemoveAll(dir); err != nil {
+			return nil, errors.Wrap(err, "cannot remove temporary folder")
+		}
+		return nil, errors.Wrap(err, "cannot load app from tar")
+	}
+	appOps := append([]func(*types.App) error{
+		types.WithCleanup(func() {
+			os.RemoveAll(dir)
+		}),
+	}, ops...)
+	return LoadFromDirectory(dir, appOps...)
+}

loader/loader_test.go

@@ -0,0 +1,117 @@
+package loader
+
+import (
+	"fmt"
+	"io/ioutil"
+	"strings"
+	"testing"
+
+	"github.com/docker/app/internal"
+	"github.com/docker/app/types"
+	"github.com/docker/docker/pkg/archive"
+	"github.com/pkg/errors"
+
+	"gotest.tools/assert"
+	is "gotest.tools/assert/cmp"
+	"gotest.tools/fs"
+)
+
+const (
+	metadata = "foo"
+	yaml     = `version: "3.1"
+
+services:
+  web:
+    image: nginx`
+	settings = "foo=bar"
+)
+
+func TestLoadFromSingleFile(t *testing.T) {
+	singlefile := fmt.Sprintf(`%s
+---
+%s
+---
+%s`, metadata, yaml, settings)
+	app, err := LoadFromSingleFile("my-app", strings.NewReader(singlefile))
+	assert.NilError(t, err)
+	assert.Assert(t, app != nil)
+	assert.Assert(t, is.Equal(app.Path, "my-app"))
+	assertAppContent(t, app)
+}
+
+func TestLoadFromSingleFileInvalidReader(t *testing.T) {
+	_, err := LoadFromSingleFile("my-app", &faultyReader{})
+	assert.ErrorContains(t, err, "faulty reader")
+}
+
+func TestLoadFromSingleFileMalformed(t *testing.T) {
+	_, err := LoadFromSingleFile("my-app", strings.NewReader(`foo
+---
+bar`))
+	assert.ErrorContains(t, err, "malformed single-file application")
+}
+
+func TestLoadFromDirectory(t *testing.T) {
+	dir := fs.NewDir(t, "my-app",
+		fs.WithFile(internal.MetadataFileName, metadata),
+		fs.WithFile(internal.SettingsFileName, settings),
+		fs.WithFile(internal.ComposeFileName, yaml),
+	)
+	defer dir.Remove()
+	app, err := LoadFromDirectory(dir.Path())
+	assert.NilError(t, err)
+	assert.Assert(t, app != nil)
+	assert.Assert(t, is.Equal(app.Path, dir.Path()))
+	assertAppContent(t, app)
+}
+
+func TestLoadFromTarInexistent(t *testing.T) {
+	_, err := LoadFromTar("any-tar.tar")
+	assert.ErrorContains(t, err, "open any-tar.tar")
+}
+
+func TestLoadFromTar(t *testing.T) {
+	myapp := createAppTar(t)
+	defer myapp.Remove()
+	app, err := LoadFromTar(myapp.Path())
+	assert.NilError(t, err)
+	assert.Assert(t, app != nil)
+	assert.Assert(t, is.Equal(app.Path, myapp.Path()))
+	assertAppContent(t, app)
+}
+
+func createAppTar(t *testing.T) *fs.File {
+	t.Helper()
+	dir := fs.NewDir(t, "my-app",
+		fs.WithFile(internal.MetadataFileName, metadata),
+		fs.WithFile(internal.SettingsFileName, settings),
+		fs.WithFile(internal.ComposeFileName, yaml),
+	)
+	defer dir.Remove()
+	r, err := archive.TarWithOptions(dir.Path(), &archive.TarOptions{
+		Compression: archive.Uncompressed,
+	})
+	assert.NilError(t, err)
+	data, err := ioutil.ReadAll(r)
+	assert.NilError(t, err)
+	return fs.NewFile(t, "app", fs.WithBytes(data))
+}
+
+func assertContentIs(t *testing.T, actual []byte, expected string) {
+	t.Helper()
+	assert.Assert(t, is.Equal(string(actual), expected))
+}
+
+func assertAppContent(t *testing.T, app *types.App) {
+	assert.Assert(t, is.Len(app.Settings(), 1))
+	assertContentIs(t, app.Settings()[0], settings)
+	assert.Assert(t, is.Len(app.Composes(), 1))
+	assertContentIs(t, app.Composes()[0], yaml)
+	assertContentIs(t, app.Metadata(), metadata)
+}
+
+type faultyReader struct{}
+
+func (r *faultyReader) Read(_ []byte) (int, error) {
+	return 0, errors.New("faulty reader")
+}

render/render.go

@@ -2,15 +2,15 @@ package render
 
 import (
 	"fmt"
-	"io/ioutil"
 	"os"
 	"regexp"
 	"strings"
 
+	"github.com/docker/app/internal/compose"
 	"github.com/docker/app/internal/renderer"
 	"github.com/docker/app/internal/settings"
 	"github.com/docker/app/internal/slices"
-	"github.com/docker/app/internal/types"
+	"github.com/docker/app/types"
 	"github.com/docker/cli/cli/compose/loader"
 	composetemplate "github.com/docker/cli/cli/compose/template"
 	composetypes "github.com/docker/cli/cli/compose/types"
@@ -39,15 +39,15 @@ var (
 
 // Render renders the Compose file for this app, merging in settings files, other compose files, and env
 // appname string, composeFiles []string, settingsFiles []string
-func Render(app types.App, env map[string]string) (*composetypes.Config, error) {
+func Render(app *types.App, env map[string]string) (*composetypes.Config, error) {
 	// prepend the app settings to the argument settings
 	// load the settings into a struct
-	fileSettings, err := settings.LoadFiles(app.SettingsFiles)
+	fileSettings, err := settings.LoadMultiple(app.Settings())
 	if err != nil {
 		return nil, errors.Wrap(err, "failed to load settings")
 	}
 	// inject our metadata
-	metaPrefixed, err := settings.LoadFile(app.MetadataFile, settings.WithPrefix("app"))
+	metaPrefixed, err := settings.Load(app.Metadata(), settings.WithPrefix("app"))
 	if err != nil {
 		return nil, err
 	}
@@ -70,21 +70,11 @@ func Render(app types.App, env map[string]string) (*composetypes.Config, error)
 		}
 		renderers = rl
 	}
-	configFiles := []composetypes.ConfigFile{}
-	for _, c := range app.ComposeFiles {
-		data, err := ioutil.ReadFile(c)
-		if err != nil {
-			return nil, errors.Wrapf(err, "failed to read Compose file %s", c)
-		}
-		s, err := renderer.Apply(string(data), allSettings, renderers...)
-		if err != nil {
-			return nil, err
-		}
-		parsed, err := loader.ParseYAML([]byte(s))
-		if err != nil {
-			return nil, errors.Wrapf(err, "failed to parse Compose file %s", c)
-		}
-		configFiles = append(configFiles, composetypes.ConfigFile{Config: parsed})
+	configFiles, err := compose.Load(app.Composes(), func(data string) (string, error) {
+		return renderer.Apply(data, allSettings, renderers...)
+	})
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to load composefiles")
 	}
 	return render(configFiles, allSettings.Flatten())
 }

types/types.go

@@ -0,0 +1,175 @@
+package types
+
+import (
+	"io"
+	"io/ioutil"
+	"path/filepath"
+
+	"github.com/docker/app/internal"
+)
+
+const SingleFileSeparator = "\n---\n"
+
+// App represents an app
+type App struct {
+	Name    string
+	Path    string
+	Cleanup func()
+
+	composesContent [][]byte
+	settingsContent [][]byte
+	metadataContent []byte
+}
+
+// Composes returns compose files content
+func (a *App) Composes() [][]byte {
+	return a.composesContent
+}
+
+// Settings returns setting files content
+func (a *App) Settings() [][]byte {
+	return a.settingsContent
+}
+
+// Metadata returns metadata file content
+func (a *App) Metadata() []byte {
+	return a.metadataContent
+}
+
+func noop() {}
+
+// NewApp creates a new docker app with the specified path and struct modifiers
+func NewApp(path string, ops ...func(*App) error) (*App, error) {
+	app := &App{
+		Name:    path,
+		Path:    path,
+		Cleanup: noop,
+
+		composesContent: [][]byte{},
+		settingsContent: [][]byte{},
+		metadataContent: []byte{},
+	}
+
+	for _, op := range ops {
+		if err := op(app); err != nil {
+			return nil, err
+		}
+	}
+
+	return app, nil
+}
+
+// NewAppFromDefaultFiles creates a new docker app using the default files in the specified path.
+// If one of those file doesn't exists, it will error out.
+func NewAppFromDefaultFiles(path string, ops ...func(*App) error) (*App, error) {
+	appOps := append([]func(*App) error{
+		MetadataFile(filepath.Join(path, internal.MetadataFileName)),
+		WithComposeFiles(filepath.Join(path, internal.ComposeFileName)),
+		WithSettingsFiles(filepath.Join(path, internal.SettingsFileName)),
+	}, ops...)
+	return NewApp(path, appOps...)
+}
+
+// WithName sets the application name
+func WithName(name string) func(*App) error {
+	return func(app *App) error {
+		app.Name = name
+		return nil
+	}
+}
+
+// WithPath sets the original path of the app
+func WithPath(path string) func(*App) error {
+	return func(app *App) error {
+		app.Path = path
+		return nil
+	}
+}
+
+// WithCleanup sets the cleanup function of the app
+func WithCleanup(f func()) func(*App) error {
+	return func(app *App) error {
+		app.Cleanup = f
+		return nil
+	}
+}
+
+// WithSettingsFiles adds the specified settings files to the app
+func WithSettingsFiles(files ...string) func(*App) error {
+	return func(app *App) error {
+		for _, file := range files {
+			d, err := ioutil.ReadFile(file)
+			if err != nil {
+				return err
+			}
+			app.settingsContent = append(app.settingsContent, d)
+		}
+		return nil
+	}
+}
+
+// WithSettings adds the specified settings readers to the app
+func WithSettings(readers ...io.Reader) func(*App) error {
+	return func(app *App) error {
+		for _, r := range readers {
+			d, err := ioutil.ReadAll(r)
+			if err != nil {
+				return err
+			}
+			app.settingsContent = append(app.settingsContent, d)
+		}
+		return nil
+	}
+}
+
+// MetadataFile adds the specified metadata file to the app
+func MetadataFile(file string) func(*App) error {
+	return func(app *App) error {
+		d, err := ioutil.ReadFile(file)
+		if err != nil {
+			return err
+		}
+		app.metadataContent = d
+		return nil
+	}
+}
+
+// Metadata adds the specified metadata reader to the app
+func Metadata(r io.Reader) func(*App) error {
+	return func(app *App) error {
+		d, err := ioutil.ReadAll(r)
+		if err != nil {
+			return err
+		}
+		app.metadataContent = d
+		return nil
+	}
+}
+
+// WithComposeFiles adds the specified compose files to the app
+func WithComposeFiles(files ...string) func(*App) error {
+	return func(app *App) error {
+		for _, file := range files {
+			d, err := ioutil.ReadFile(file)
+			if err != nil {
+				return err
+			}
+			app.composesContent = append(app.composesContent, d)
+		}
+		return nil
+	}
+}
+
+// WithComposes adds the specified compose readers to the app
+func WithComposes(readers ...io.Reader) func(*App) error {
+	return func(app *App) error {
+		for _, r := range readers {
+			d, err := ioutil.ReadAll(r)
+			if err != nil {
+				return err
+			}
+			app.composesContent = append(app.composesContent, d)
+		}
+		return nil
+	}
+}

types/types_test.go

@@ -0,0 +1,146 @@
+package types
+
+import (
+	"errors"
+	"strings"
+	"testing"
+
+	"github.com/docker/app/internal"
+
+	"gotest.tools/assert"
+	is "gotest.tools/assert/cmp"
+	"gotest.tools/fs"
+)
+
+const (
+	yaml = `version: "3.0"
+services:
+  web:
+    image: nginx`
+)
+
+func TestNewApp(t *testing.T) {
+	app, err := NewApp("any-app")
+	assert.NilError(t, err)
+	assert.Assert(t, is.Equal(app.Path, "any-app"))
+}
+
+func TestNewAppFromDefaultFiles(t *testing.T) {
+	dir := fs.NewDir(t, "my-app",
+		fs.WithFile(internal.MetadataFileName, "foo"),
+		fs.WithFile(internal.SettingsFileName, "foo=bar"),
+		fs.WithFile(internal.ComposeFileName, yaml),
+	)
+	defer dir.Remove()
+	app, err := NewAppFromDefaultFiles(dir.Path())
+	assert.NilError(t, err)
+	assert.Assert(t, is.Len(app.Settings(), 1))
+	assertContentIs(t, app.Settings()[0], "foo=bar")
+	assert.Assert(t, is.Len(app.Composes(), 1))
+	assertContentIs(t, app.Composes()[0], yaml)
+	assertContentIs(t, app.Metadata(), "foo")
+}
+
+func TestNewAppWithOpError(t *testing.T) {
+	_, err := NewApp("any-app", func(_ *App) error { return errors.New("error creating") })
+	assert.ErrorContains(t, err, "error creating")
+}
+
+func TestWithPath(t *testing.T) {
+	app := &App{Path: "any-app"}
+	err := WithPath("any-path")(app)
+	assert.NilError(t, err)
+	assert.Assert(t, is.Equal(app.Path, "any-path"))
+}
+
+func TestWithCleanup(t *testing.T) {
+	app := &App{Path: "any-app"}
+	err := WithCleanup(func() {})(app)
+	assert.NilError(t, err)
+	assert.Assert(t, app.Cleanup != nil)
+}
+
+func TestWithSettingsFilesError(t *testing.T) {
+	app := &App{Path: "any-app"}
+	err := WithSettingsFiles("any-settings-file")(app)
+	assert.ErrorContains(t, err, "open any-settings-file")
+}
+
+func TestWithSettingsFiles(t *testing.T) {
+	dir := fs.NewDir(t, "settings",
+		fs.WithFile("my-settings-file", "foo"),
+	)
+	defer dir.Remove()
+	app := &App{Path: "my-app"}
+	err := WithSettingsFiles(dir.Join("my-settings-file"))(app)
+	assert.NilError(t, err)
+	assert.Assert(t, is.Len(app.Settings(), 1))
+	assertContentIs(t, app.Settings()[0], "foo")
+}
+
+func TestWithSettings(t *testing.T) {
+	r := strings.NewReader("foo")
+	app := &App{Path: "my-app"}
+	err := WithSettings(r)(app)
+	assert.NilError(t, err)
+	assert.Assert(t, is.Len(app.Settings(), 1))
+	assertContentIs(t, app.Settings()[0], "foo")
+}
+
+func TestWithComposeFilesError(t *testing.T) {
+	app := &App{Path: "any-app"}
+	err := WithComposeFiles("any-compose-file")(app)
+	assert.ErrorContains(t, err, "open any-compose-file")
+}
+
+func TestWithComposeFiles(t *testing.T) {
+	dir := fs.NewDir(t, "composes",
+		fs.WithFile("my-compose-file", yaml),
+	)
+	defer dir.Remove()
+	app := &App{Path: "my-app"}
+	err := WithComposeFiles(dir.Join("my-compose-file"))(app)
+	assert.NilError(t, err)
+	assert.Assert(t, is.Len(app.Composes(), 1))
+	assertContentIs(t, app.Composes()[0], yaml)
+}
+
+func TestWithComposes(t *testing.T) {
+	r := strings.NewReader(yaml)
+	app := &App{Path: "my-app"}
+	err := WithComposes(r)(app)
+	assert.NilError(t, err)
+	assert.Assert(t, is.Len(app.Composes(), 1))
+	assertContentIs(t, app.Composes()[0], yaml)
+}
+
+func TestMetadataFileError(t *testing.T) {
+	app := &App{Path: "any-app"}
+	err := MetadataFile("any-metadata-file")(app)
+	assert.ErrorContains(t, err, "open any-metadata-file")
+}
+
+func TestMetadataFile(t *testing.T) {
+	dir := fs.NewDir(t, "metadata",
+		fs.WithFile("my-metadata-file", "foo"),
+	)
+	defer dir.Remove()
+	app := &App{Path: "my-app"}
+	err := MetadataFile(dir.Join("my-metadata-file"))(app)
+	assert.NilError(t, err)
+	assert.Assert(t, app.Metadata() != nil)
+	assertContentIs(t, app.Metadata(), "foo")
+}
+
+func TestMetadata(t *testing.T) {
+	r := strings.NewReader("foo")
+	app := &App{Path: "my-app"}
+	err := Metadata(r)(app)
+	assert.NilError(t, err)
+	assertContentIs(t, app.Metadata(), "foo")
+}
+
+func assertContentIs(t *testing.T, data []byte, expected string) {
+	t.Helper()
+	assert.Assert(t, is.Equal(string(data), expected))
+}