Adds minimum API version to version

Signed-off-by: John Howard <jhoward@microsoft.com>

api/types/types.go

@@ -133,6 +133,7 @@ type ContainerProcessList struct {
 type Version struct {
 	Version       string
 	APIVersion    string `json:"ApiVersion"`
+	MinAPIVersion string `json:"MinAPIVersion,omitempty"`
 	GitCommit     string
 	GoVersion     string
 	Os            string

cli/command/system/version.go

@@ -25,6 +25,7 @@ var versionTemplate = `Client:
 Server:
  Version:             {{.Server.Version}}
  API version:         {{.Server.APIVersion}}
+ Minimum API version: {{.Server.MinAPIVersion}}
  Go version:          {{.Server.GoVersion}}
  Git commit:          {{.Server.GitCommit}}
  Built:               {{.Server.BuildTime}}

daemon/info.go

@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"github.com/Sirupsen/logrus"
+	"github.com/docker/docker/api"
 	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/container"
 	"github.com/docker/docker/dockerversion"
@@ -158,6 +159,7 @@ func (daemon *Daemon) SystemVersion() types.Version {
 	v := types.Version{
 		Version:       dockerversion.Version,
 		GitCommit:     dockerversion.GitCommit,
+		MinAPIVersion: api.MinVersion,
 		GoVersion:     runtime.Version(),
 		Os:            runtime.GOOS,
 		Arch:          runtime.GOARCH,

docs/reference/api/docker_remote_api.md

@@ -130,6 +130,7 @@ This section lists each version from latest to oldest.  Each listing includes a
 
 [Docker Remote API v1.25](docker_remote_api_v1.25.md) documentation
 
+* `GET /version` now returns `MinAPIVersion`.
 * `POST /build` accepts `networkmode` parameter to specify network used during build.
 * `GET /images/(name)/json` now returns `OsVersion` if populated
 * `GET /info` now returns `Isolation`.

docs/reference/api/docker_remote_api_v1.25.md

@@ -2741,6 +2741,7 @@ Show the docker version information
          "GitCommit": "deadbee",
          "Arch": "amd64",
          "ApiVersion": "1.25",
+         "MinAPIVersion": "1.12",
          "BuildTime": "2016-06-14T07:09:13.444803460+00:00",
          "Experimental": true
     }

integration-cli/docker_cli_version_test.go

@@ -14,7 +14,7 @@ func (s *DockerSuite) TestVersionEnsureSucceeds(c *check.C) {
 		"Client:":       1,
 		"Server:":       1,
 		" Version:":     2,
-		" API version:": 2,
+		" API version:": 3,
 		" Go version:":  2,
 		" Git commit:":  2,
 		" OS/Arch:":     2,