Add the docker app version in the bundle

This will help us track what we can or not do with the bundle we are
dealing with.

Signed-off-by: Djordje Lukic <djordje.lukic@docker.com>

internal/names.go

@@ -69,6 +69,10 @@ const (
 	// DockerInspectFormatEnvVar is the environment variable set by the CNAB runtime to select
 	// the inspect output format.
 	DockerInspectFormatEnvVar = "DOCKER_INSPECT_FORMAT"
+
+	// CustomDockerAppVersionName is the custom variable set by Docker App to
+	// save the version of Docker App that built the bundle.
+	CustomDockerAppVersionName = Namespace + "version"
 )
 
 var (

internal/packager/cnab.go

@@ -142,6 +142,9 @@ func ToCNAB(app *types.App, invocationImageName string) (*bundle.Bundle, error)
 
 	bndl := &bundle.Bundle{
 		SchemaVersion: CNABVersion1_0_0,
+		Custom: map[string]interface{}{
+			internal.CustomDockerAppVersionName: internal.Version,
+		},
 		Credentials: map[string]bundle.Credential{
 			internal.CredentialDockerContextName: {
 				Location: bundle.Location{

internal/packager/cnab_test.go

@@ -2,8 +2,11 @@ package packager
 
 import (
 	"encoding/json"
+	"fmt"
 	"testing"
 
+	"github.com/docker/app/internal"
+
 	"gotest.tools/golden"
 
 	"github.com/docker/app/types"
@@ -17,5 +20,7 @@ func TestToCNAB(t *testing.T) {
 	assert.NilError(t, err)
 	actualJSON, err := json.MarshalIndent(actual, "", "  ")
 	assert.NilError(t, err)
-	golden.Assert(t, string(actualJSON), "bundle-json.golden")
+	s := golden.Get(t, "bundle-json.golden")
+	expected := fmt.Sprintf(string(s), internal.Version)
+	assert.Equal(t, string(actualJSON), expected)
 }

internal/packager/testdata/bundle-json.golden

@@ -162,5 +162,8 @@
       "default": "foo",
       "type": "string"
     }
+  },
+  "custom": {
+    "com.docker.app.version": "%s"
   }
 }