Add the mediaType to the error

Doug Davis · Doug Davis · commit c127d9614f5b · 2017-02-28T11:36:32.000-08:00
Without this fix the error the client might see is:
	target is unknown
which wasn't helpful to me when I saw this today. With this fix I
now see:
	MediaType is unknown: 'text/html'
which helped me track down the issue to the registry I was talking to.

Signed-off-by: Doug Davis &lt;dug@us.ibm.com&gt;
diff --git a/cli/command/image/pull.go b/cli/command/image/pull.go
@@ -76,7 +76,7 @@ func runPull(dockerCli *command.DockerCli, opts pullOptions) error {
 		err = imagePullPrivileged(ctx, dockerCli, authConfig, reference.FamiliarString(distributionRef), requestPrivilege, opts.all)
 	}
 	if err != nil {
-		if strings.Contains(err.Error(), "target is plugin") {
+		if strings.Contains(err.Error(), "when fetching 'plugin'") {
 			return errors.New(err.Error() + " - Use `docker plugin install`")
 		}
 		return err
diff --git a/cli/command/plugin/install.go b/cli/command/plugin/install.go
@@ -152,7 +152,7 @@ func runInstall(dockerCli *command.DockerCli, opts pluginOptions) error {
 
 	responseBody, err := dockerCli.Client().PluginInstall(ctx, alias, options)
 	if err != nil {
-		if strings.Contains(err.Error(), "target is image") {
+		if strings.Contains(err.Error(), "(image) when fetching") {
 			return errors.New(err.Error() + " - Use `docker image pull`")
 		}
 		return err
diff --git a/distribution/pull_v2.go b/distribution/pull_v2.go
@@ -363,7 +363,7 @@ func (p *v2Puller) pullV2Tag(ctx context.Context, ref reference.Named) (tagUpdat
 			if configClass == "" {
 				configClass = "unknown"
 			}
-			return false, fmt.Errorf("target is %s", configClass)
+			return false, fmt.Errorf("Encountered remote %q(%s) when fetching", m.Manifest.Config.MediaType, configClass)
 		}
 	}
 
diff --git a/integration-cli/docker_cli_plugins_test.go b/integration-cli/docker_cli_plugins_test.go
@@ -181,7 +181,7 @@ func (s *DockerRegistrySuite) TestPluginInstallImage(c *check.C) {
 
 	out, _, err := dockerCmdWithError("plugin", "install", repoName)
 	c.Assert(err, checker.NotNil)
-	c.Assert(out, checker.Contains, "target is image")
+	c.Assert(out, checker.Contains, `Encountered remote "application/vnd.docker.container.image.v1+json"(image) when fetching`)
 }
 
 func (s *DockerSuite) TestPluginEnableDisableNegative(c *check.C) {

Original file line number	Diff line number	Diff line change
`@@ -76,7 +76,7 @@ func runPull(dockerCli *command.DockerCli, opts pullOptions) error {`
`76`	`76`	`err = imagePullPrivileged(ctx, dockerCli, authConfig, reference.FamiliarString(distributionRef), requestPrivilege, opts.all)`
`77`	`77`	`}`
`78`	`78`	`if err != nil {`
`79`		`- if strings.Contains(err.Error(), "target is plugin") {`
	`79`	`+ if strings.Contains(err.Error(), "when fetching 'plugin'") {`
`80`	`80`	return errors.New(err.Error() + " - Use `docker plugin install`")
`81`	`81`	`}`
`82`	`82`	`return err`
Original file line number	Diff line number	Diff line change
`@@ -152,7 +152,7 @@ func runInstall(dockerCli *command.DockerCli, opts pluginOptions) error {`
`152`	`152`
`153`	`153`	`responseBody, err := dockerCli.Client().PluginInstall(ctx, alias, options)`
`154`	`154`	`if err != nil {`
`155`		`- if strings.Contains(err.Error(), "target is image") {`
	`155`	`+ if strings.Contains(err.Error(), "(image) when fetching") {`
`156`	`156`	return errors.New(err.Error() + " - Use `docker image pull`")
`157`	`157`	`}`
`158`	`158`	`return err`
Original file line number	Diff line number	Diff line change
`@@ -363,7 +363,7 @@ func (p *v2Puller) pullV2Tag(ctx context.Context, ref reference.Named) (tagUpdat`
`363`	`363`	`if configClass == "" {`
`364`	`364`	`configClass = "unknown"`
`365`	`365`	`}`
`366`		`- return false, fmt.Errorf("target is %s", configClass)`
	`366`	`+ return false, fmt.Errorf("Encountered remote %q(%s) when fetching", m.Manifest.Config.MediaType, configClass)`
`367`	`367`	`}`
`368`	`368`	`}`
`369`	`369`
Original file line number	Diff line number	Diff line change
`@@ -181,7 +181,7 @@ func (s DockerRegistrySuite) TestPluginInstallImage(c check.C) {`
`181`	`181`
`182`	`182`	`out, _, err := dockerCmdWithError("plugin", "install", repoName)`
`183`	`183`	`c.Assert(err, checker.NotNil)`
`184`		`- c.Assert(out, checker.Contains, "target is image")`
	`184`	+ c.Assert(out, checker.Contains, `Encountered remote "application/vnd.docker.container.image.v1+json"(image) when fetching`)
`185`	`185`	`}`
`186`	`186`
`187`	`187`	`func (s DockerSuite) TestPluginEnableDisableNegative(c check.C) {`