Merge pull request #500 from chris-crone/improve-missing-invoc-img-err

Improve missing invoc img err

Author: simonferquel

internal/commands/bundle.go

@@ -8,6 +8,7 @@ import (
 	"io/ioutil"
 
 	"github.com/deislabs/duffle/pkg/bundle"
+	"github.com/docker/app/internal"
 	"github.com/docker/app/internal/packager"
 	"github.com/docker/app/types"
 	"github.com/docker/app/types/metadata"
@@ -90,6 +91,11 @@ func makeBundleFromApp(dockerCli command.Cli, app *types.App) (*bundle.Bundle, e
 	defer buildResp.Body.Close()
 
 	if err := jsonmessage.DisplayJSONMessagesStream(buildResp.Body, ioutil.Discard, 0, false, func(jsonmessage.JSONMessage) {}); err != nil {
+		// If the invocation image can't be found we will get an error of the form:
+		// manifest for docker/cnab-app-base:v0.6.0-202-gbaf0b246c7 not found
+		if err.Error() == fmt.Sprintf("manifest for %s:%s not found", packager.CNABBaseImageName, internal.Version) {
+			return nil, fmt.Errorf("unable to resolve Docker App base image: %s:%s", packager.CNABBaseImageName, internal.Version)
+		}
 		return nil, err
 	}
 	return packager.ToCNAB(app, invocationImageName)

internal/packager/packing.go

@@ -14,10 +14,15 @@ import (
 	"github.com/pkg/errors"
 )
 
-var dockerFile = `FROM docker/cnab-app-base:` + internal.Version + `
-COPY . .`
+const (
+	// CNABBaseImageName is the name of the base invocation image.
+	CNABBaseImageName = "docker/cnab-app-base"
+
+	dockerIgnore = "Dockerfile"
+)
 
-const dockerIgnore = "Dockerfile"
+var dockerFile = `FROM ` + CNABBaseImageName + `:` + internal.Version + `
+COPY . .`
 
 func tarAdd(tarout *tar.Writer, path, file string) error {
 	payload, err := ioutil.ReadFile(file)