Add arg to not execute docker build instructions

cli.go

@@ -81,6 +81,7 @@ type TGFApplication struct {
 	LoggingLevel      string
 	MountPoint        string
 	NoAWS             bool
+	NoDockerBuild     bool
 	NoHome            bool
 	NoTemp            bool
 	PruneImages       bool
@@ -99,6 +100,7 @@ func (app *TGFApplication) parse() *TGFApplication {
 	app.Switch("get-image-name", "Just return the resulting image name (alias --gi)").BoolVar(&app.GetImageName)
 	app.Switch("interactive", "On by default, use --no-interactive or --no-it to disable launching Docker in interactive mode or set "+envInteractive+" to 0 or false").Envar(envInteractive).BoolVar(&app.DockerInteractive)
 	app.Switch("local-image", "If set, TGF will not pull the image when refreshing (alias --li)").BoolVar(&app.UseLocalImage)
+	app.Switch("no-docker-build", "Disable docker build instructions configured in the config files (alias --nb)").BoolVar(&app.NoDockerBuild)
 	app.Switch("no-home", "Disable the mapping of the home directory (alias --nh) or set "+envNoHome).Envar(envNoHome).BoolVar(&app.NoHome)
 	app.Switch("no-temp", "Disable the mapping of the temp directory (alias --nt) or set "+envNoTemp).Envar(envNoTemp).BoolVar(&app.NoTemp)
 	app.Switch("no-aws", "Disable use of AWS to get configuration (alias --na) or set "+envNoAWS).Envar(envNoAWS).BoolVar(&app.NoAWS)
@@ -126,6 +128,7 @@ func (app *TGFApplication) parse() *TGFApplication {
 	app.Switch("it", "alias for interactive").Hidden().BoolVar(&app.DockerInteractive)
 	app.Switch("li", "alias for local-image").Hidden().BoolVar(&app.UseLocalImage)
 	app.Switch("na", "alias for no-aws").Hidden().BoolVar(&app.NoAWS)
+	app.Switch("nb", "alias for no-docker-build").Hidden().BoolVar(&app.NoDockerBuild)
 	app.Switch("nh", "alias for no-home").Hidden().BoolVar(&app.NoHome)
 	app.Switch("nt", "alias for no-temp").Hidden().BoolVar(&app.NoTemp)
 	app.Switch("ri", "alias for refresh-image)").Hidden().BoolVar(&app.Refresh)

docker.go

@@ -61,7 +61,7 @@ func callDocker(config *TGFConfig, args ...string) int {
 		command = append(command, "--terragrunt-source-update")
 	}
 
-	imageName := getImage(config)
+	imageName := getImage(config, app.NoDockerBuild, app.Refresh, app.UseLocalImage)
 
 	if app.GetImageName {
 		Println(imageName)
@@ -206,12 +206,16 @@ func runCommands(commands []string) error {
 
 // Returns the image name to use
 // If docker-image-build option has been set, an image is dynamically built and the resulting image digest is returned
-func getImage(config *TGFConfig) (name string) {
+func getImage(config *TGFConfig, noDockerBuild bool, refresh bool, useLocalImage bool) (name string) {
 	name = config.GetImageName()
 	if !strings.Contains(name, ":") {
 		name += ":latest"
 	}
 
+	if noDockerBuild {
+		return
+	}
+
 	lastHash := ""
 	for i, ib := range config.imageBuildConfigs {
 		var temp, folder, dockerFile string
@@ -258,10 +262,10 @@ func getImage(config *TGFConfig) (name string) {
 		if image, tag := Split2(name, ":"); len(tag) > maxDockerTagLength {
 			name = image + ":" + tag[0:maxDockerTagLength]
 		}
-		if app.Refresh || getImageHash(name) != ib.hash() {
+		if refresh || getImageHash(name) != ib.hash() {
 			label := fmt.Sprintf("hash=%s", ib.hash())
 			args := []string{"build", ".", "-f", dockerfilePattern, "--quiet", "--force-rm", "--label", label}
-			if i == 0 && app.Refresh && !app.UseLocalImage {
+			if i == 0 && refresh && !useLocalImage {
 				args = append(args, "--pull")
 			}
 			if dockerFile != "" {
@@ -279,13 +283,21 @@ func getImage(config *TGFConfig) (name string) {
 			buildCmd.Stderr = os.Stderr
 			buildCmd.Dir = folder
 			must(buildCmd.Output())
-			prune(config)
+			pruneDangling(config)
 		}
 	}
 
 	return
 }
 
+var pruneDangling = func(config *TGFConfig) {
+	cli, ctx := getDockerClient()
+	danglingFilters := filters.NewArgs()
+	danglingFilters.Add("dangling", "true")
+	must(cli.ImagesPrune(ctx, danglingFilters))
+	must(cli.ContainersPrune(ctx, filters.Args{}))
+}
+
 func prune(config *TGFConfig, images ...string) {
 	cli, ctx := getDockerClient()
 	if len(images) > 0 {
@@ -318,11 +330,7 @@ func prune(config *TGFConfig, images ...string) {
 			}
 		}
 	}
-
-	danglingFilters := filters.NewArgs()
-	danglingFilters.Add("dangling", "true")
-	must(cli.ImagesPrune(ctx, danglingFilters))
-	must(cli.ContainersPrune(ctx, filters.Args{}))
+	pruneDangling(config)
 }
 
 func deleteImage(id string) {
@@ -343,7 +351,7 @@ func deleteImage(id string) {
 
 // GetActualImageVersion returns the real image version stored in the environment variable TGF_IMAGE_VERSION
 func GetActualImageVersion(config *TGFConfig) string {
-	return getActualImageVersionInternal(getImage(config))
+	return getActualImageVersionInternal(getImage(config, app.NoDockerBuild, app.Refresh, app.UseLocalImage))
 }
 
 func getDockerClient() (*client.Client, context.Context) {

docker_test.go

@@ -0,0 +1,96 @@
+package main
+
+import (
+	"os/exec"
+	"strconv"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetImage(t *testing.T) {
+	t.Parallel()
+
+	pruneDangling = func(*TGFConfig) {}
+
+	testImageName := "test-image" + strconv.Itoa(randInt())
+	testTag := "test" + strconv.Itoa(randInt())
+
+	// build test image
+	c1 := exec.Command("echo", "-e", "FROM scratch\nLABEL name="+testTag)
+	c2 := exec.Command("docker", "build", "-", "-t", testImageName+":"+testTag)
+	c2.Stdin, _ = c1.StdoutPipe()
+	c2.Start()
+	c1.Run()
+	c2.Wait()
+
+	tests := []struct {
+		name          string
+		config        *TGFConfig
+		noDockerBuild bool
+		refresh       bool
+		useLocalImage bool
+		result        string
+	}{
+		{
+			name:          "Without build configs and tag",
+			config:        &TGFConfig{Image: testImageName},
+			noDockerBuild: false,
+			refresh:       false,
+			useLocalImage: false,
+			result:        testImageName + ":latest",
+		},
+		{
+			name: "Without build configs but with a tag",
+			config: &TGFConfig{
+				Image:    testImageName,
+				ImageTag: &testTag,
+			},
+			noDockerBuild: false,
+			refresh:       false,
+			useLocalImage: false,
+			result:        testImageName + ":" + testTag,
+		},
+		{
+			name: "With build config",
+			config: &TGFConfig{
+				ImageTag: &testTag,
+				Image:    testImageName,
+				imageBuildConfigs: []TGFConfigBuild{
+					TGFConfigBuild{
+						Instructions: "LABEL another=test",
+						Tag:          "buildtag",
+					},
+				},
+			},
+			noDockerBuild: false,
+			refresh:       false,
+			useLocalImage: true,
+			result:        testImageName + ":" + testTag + "-" + "buildtag",
+		},
+		{
+			name: "With build config and no build flag",
+			config: &TGFConfig{
+				ImageTag: &testTag,
+				Image:    testImageName,
+				imageBuildConfigs: []TGFConfigBuild{
+					TGFConfigBuild{
+						Instructions: "LABEL another=test",
+						Tag:          "buildtag",
+					},
+				},
+			},
+			noDockerBuild: true,
+			refresh:       false,
+			useLocalImage: true,
+			result:        testImageName + ":" + testTag,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			app = NewTGFApplication()
+			assert.Equal(t, tt.result, getImage(tt.config, tt.noDockerBuild, tt.refresh, tt.useLocalImage), "The result image tag is not correct")
+		})
+	}
+}