Implement docker exec with standalone client lib.

Signed-off-by: David Calavera <david.calavera@gmail.com>

client/container_attach.go

@@ -10,7 +10,7 @@ import (
 // It returns a types.HijackedConnection with the hijacked connection
 // and the a reader to get output. It's up to the called to close
 // the hijacked connection by calling types.HijackedResponse.Close.
-func (cli *Client) ContainerAttach(options types.ContainerAttachOptions) (*types.HijackedResponse, error) {
+func (cli *Client) ContainerAttach(options types.ContainerAttachOptions) (types.HijackedResponse, error) {
 	query := url.Values{}
 	if options.Stream {
 		query.Set("stream", "1")

client/exec.go

@@ -0,0 +1,49 @@
+package lib
+
+import (
+	"encoding/json"
+
+	"github.com/docker/docker/api/types"
+	"github.com/docker/docker/runconfig"
+)
+
+// ContainerExecCreate creates a new exec configuration to run an exec process.
+func (cli *Client) ContainerExecCreate(config runconfig.ExecConfig) (types.ContainerExecCreateResponse, error) {
+	var response types.ContainerExecCreateResponse
+	resp, err := cli.post("/containers/"+config.Container+"/exec", nil, config, nil)
+	if err != nil {
+		return response, err
+	}
+	defer ensureReaderClosed(resp)
+	err = json.NewDecoder(resp.body).Decode(&response)
+	return response, err
+}
+
+// ContainerExecStart starts an exec process already create in the docker host.
+func (cli *Client) ContainerExecStart(execID string, config types.ExecStartCheck) error {
+	resp, err := cli.post("/exec/"+execID+"/start", nil, config, nil)
+	ensureReaderClosed(resp)
+	return err
+}
+
+// ContainerExecAttach attaches a connection to an exec process in the server.
+// It returns a types.HijackedConnection with the hijacked connection
+// and the a reader to get output. It's up to the called to close
+// the hijacked connection by calling types.HijackedResponse.Close.
+func (cli *Client) ContainerExecAttach(execID string, config runconfig.ExecConfig) (types.HijackedResponse, error) {
+	headers := map[string][]string{"Content-Type": {"application/json"}}
+	return cli.postHijacked("/exec/"+execID+"/start", nil, config, headers)
+}
+
+// ContainerExecInspect returns information about a specific exec process on the docker host.
+func (cli *Client) ContainerExecInspect(execID string) (types.ContainerExecInspect, error) {
+	var response types.ContainerExecInspect
+	resp, err := cli.get("/exec/"+execID+"/json", nil, nil)
+	if err != nil {
+		return response, err
+	}
+	defer ensureReaderClosed(resp)
+
+	err = json.NewDecoder(resp.body).Decode(&response)
+	return response, err
+}

client/hijack.go

@@ -4,7 +4,6 @@ import (
 	"crypto/tls"
 	"errors"
 	"fmt"
-	"io"
 	"net"
 	"net/http/httputil"
 	"net/url"
@@ -30,15 +29,15 @@ func (c *tlsClientCon) CloseWrite() error {
 }
 
 // postHijacked sends a POST request and hijacks the connection.
-func (cli *Client) postHijacked(path string, query url.Values, body io.Reader, headers map[string][]string) (*types.HijackedResponse, error) {
+func (cli *Client) postHijacked(path string, query url.Values, body interface{}, headers map[string][]string) (types.HijackedResponse, error) {
 	bodyEncoded, err := encodeData(body)
 	if err != nil {
-		return nil, err
+		return types.HijackedResponse{}, err
 	}
 
 	req, err := cli.newRequest("POST", path, query, bodyEncoded, headers)
 	if err != nil {
-		return nil, err
+		return types.HijackedResponse{}, err
 	}
 	req.Host = cli.Addr
 
@@ -48,9 +47,9 @@ func (cli *Client) postHijacked(path string, query url.Values, body io.Reader, h
 	conn, err := dial(cli.Proto, cli.Addr, cli.tlsConfig)
 	if err != nil {
 		if strings.Contains(err.Error(), "connection refused") {
-			return nil, fmt.Errorf("Cannot connect to the Docker daemon. Is 'docker daemon' running on this host?")
+			return types.HijackedResponse{}, fmt.Errorf("Cannot connect to the Docker daemon. Is 'docker daemon' running on this host?")
 		}
-		return nil, err
+		return types.HijackedResponse{}, err
 	}
 
 	// When we set up a TCP connection for hijack, there could be long periods
@@ -71,7 +70,7 @@ func (cli *Client) postHijacked(path string, query url.Values, body io.Reader, h
 
 	rwc, br := clientconn.Hijack()
 
-	return &types.HijackedResponse{rwc, br}, nil
+	return types.HijackedResponse{rwc, br}, nil
 }
 
 func tlsDial(network, addr string, config *tls.Config) (net.Conn, error) {

types/client.go

@@ -31,6 +31,14 @@ type ContainerCommitOptions struct {
 	JSONConfig     string
 }
 
+// ContainerExecInspect holds information returned by exec inspect.
+type ContainerExecInspect struct {
+	ExecID      string
+	ContainerID string
+	Running     bool
+	ExitCode    int
+}
+
 // ContainerListOptions holds parameters to list containers with.
 type ContainerListOptions struct {
 	Quiet  bool