Introduce --iidfile option

Signed-off-by: Nicolas De Loof <nicolas.deloof@gmail.com>

e2e/build_test.go

@@ -2,7 +2,9 @@ package e2e
 
 import (
 	"encoding/json"
+	"github.com/docker/app/internal/store"
 	"io/ioutil"
+	"os"
 	"path"
 	"strings"
 	"testing"
@@ -15,9 +17,12 @@ import (
 func TestBuild(t *testing.T) {
 	runWithDindSwarmAndRegistry(t, func(info dindSwarmAndRegistryInfo) {
 		cmd := info.configuredCmd
+		tmp := os.TempDir()
+		defer os.RemoveAll(tmp)
 
 		testDir := path.Join("testdata", "build")
-		cmd.Command = dockerCli.Command("app", "build", "--tag", "single:1.0.0", "-f", path.Join(testDir, "single.dockerapp"), testDir)
+		iidfile := path.Join(tmp, "iid")
+		cmd.Command = dockerCli.Command("app", "build", "--tag", "single:1.0.0", "--iidfile", iidfile, "-f", path.Join(testDir, "single.dockerapp"), testDir)
 		icmd.RunCmd(cmd).Assert(t, icmd.Success)
 
 		cfg := getDockerConfigDir(t, cmd)
@@ -34,6 +39,15 @@ func TestBuild(t *testing.T) {
 			cmd.Command = dockerCli.Command("inspect", ref)
 			icmd.RunCmd(cmd).Assert(t, icmd.Success)
 		}
+
+		_, err = os.Stat(iidfile)
+		assert.NilError(t, err)
+		bytes, err := ioutil.ReadFile(iidfile)
+		assert.NilError(t, err)
+		iid := string(bytes)
+		actualID, err := store.FromBundle(&bndl)
+		assert.NilError(t, err)
+		assert.Equal(t, iid, actualID)
 	})
 }
 

internal/commands/build/build.go

@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"github.com/docker/app/internal/store"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -32,12 +33,13 @@ import (
 )
 
 type buildOptions struct {
-	noCache  bool
-	progress string
-	pull     bool
-	tag      string
-	folder   string
-	args     []string
+	noCache     bool
+	progress    string
+	pull        bool
+	tag         string
+	folder      string
+	imageIDFile string
+	args        []string
 }
 
 func Cmd(dockerCli command.Cli) *cobra.Command {
@@ -63,6 +65,7 @@ func Cmd(dockerCli command.Cli) *cobra.Command {
 	flags.StringVarP(&opts.folder, "folder", "f", "", "Docker app folder containing application definition")
 	flags.BoolVar(&opts.pull, "pull", false, "Always attempt to pull a newer version of the image")
 	flags.StringArrayVar(&opts.args, "build-arg", []string{}, "Set build-time variables")
+	flags.StringVar(&opts.imageIDFile, "iidfile", "", "Write the app image ID to the file")
 
 	return cmd
 }
@@ -138,6 +141,16 @@ func runBuild(dockerCli command.Cli, contextPath string, opt buildOptions) (refe
 		return nil, err
 	}
 
+	if opt.imageIDFile != "" {
+		id, err := store.FromBundle(bundle)
+		if err != nil {
+			return nil, err
+		}
+		if err = ioutil.WriteFile(opt.imageIDFile, []byte(id.String()), 0644); err != nil {
+			return nil, err
+		}
+	}
+
 	return packager.PersistInBundleStore(ref, bundle)
 }