images/builder: Allow GCB builds from arbitrary build directories

- Remove cdToRootDir
    This function was not actually cd-ing into directories
- Add --build-dir flag to support builds that require the entire
   repo/workspace to be uploaded to GCB
- Add a validation method to ensure config directory and cloudbuild.yaml
   exist before submitting build

Signed-off-by: Stephen Augustus <saugustus@vmware.com>

Author: justaugustus

images/builder/main.go

@@ -54,21 +54,26 @@ func getVersion() (string, error) {
 	return fmt.Sprintf("v%s-%s", t, strings.TrimSpace(string(output))), nil
 }
 
-func cdToRootDir() error {
-	if bazelWorkspace := os.Getenv("BUILD_WORKSPACE_DIRECTORY"); bazelWorkspace != "" {
-		if err := os.Chdir(bazelWorkspace); err != nil {
-			return fmt.Errorf("failed to chdir to bazel workspace (%s): %v", bazelWorkspace, err)
-		}
+func (o *options) validateConfigDir() error {
+	configDir := o.configDir
+	dirInfo, err := os.Stat(o.configDir)
+	if os.IsNotExist(err) {
+		log.Fatalf("Config directory (%s) does not exist", configDir)
 	}
-	cmd := exec.Command("git", "rev-parse", "--show-toplevel")
-	output, err := cmd.Output()
-	if err != nil {
-		return err
+
+	if !dirInfo.IsDir() {
+		log.Fatalf("Config directory (%s) is not actually a directory", configDir)
 	}
-	return os.Chdir(strings.TrimSpace(string(output)))
+
+	_, err = os.Stat(path.Join(configDir, o.cloudbuildFile))
+	if os.IsNotExist(err) {
+		log.Fatalf("%s does not exist", o.cloudbuildFile)
+	}
+
+	return nil
 }
 
-func uploadWorkingDir(targetBucket string) (string, error) {
+func (o *options) uploadBuildDir(targetBucket string) (string, error) {
 	f, err := ioutil.TempFile("", "")
 	if err != nil {
 		return "", fmt.Errorf("failed to create temp file: %v", err)
@@ -112,7 +117,7 @@ func runSingleJob(o options, jobName, uploaded, version string, subs map[string]
 	s = append(s, "_GIT_TAG="+version)
 	args := []string{
 		"builds", "submit",
-		"--config", path.Join(o.imageDirectory, "cloudbuild.yaml"),
+		"--config", o.cloudbuildFile,
 		"--substitutions", strings.Join(s, ","),
 	}
 	if o.project != "" {
@@ -153,7 +158,7 @@ func runSingleJob(o options, jobName, uploaded, version string, subs map[string]
 type variants map[string]map[string]string
 
 func getVariants(o options) (variants, error) {
-	content, err := ioutil.ReadFile(path.Join(o.imageDirectory, "variants.yaml"))
+	content, err := ioutil.ReadFile("variants.yaml")
 	if err != nil {
 		if !os.IsNotExist(err) {
 			return nil, fmt.Errorf("failed to load variants.yaml: %v", err)
@@ -183,7 +188,7 @@ func runBuildJobs(o options) []error {
 	var uploaded string
 	if o.scratchBucket != "" {
 		var err error
-		uploaded, err = uploadWorkingDir(o.scratchBucket + gcsSourceDir)
+		uploaded, err = o.uploadBuildDir(o.scratchBucket + gcsSourceDir)
 		if err != nil {
 			return []error{fmt.Errorf("failed to upload source: %v", err)}
 		}
@@ -236,9 +241,11 @@ func runBuildJobs(o options) []error {
 }
 
 type options struct {
+	buildDir       string
+	configDir      string
+	cloudbuildFile string
 	logDir         string
 	scratchBucket  string
-	imageDirectory string
 	project        string
 	allowDirty     bool
 	variant        string
@@ -257,30 +264,58 @@ func mergeMaps(maps ...map[string]string) map[string]string {
 
 func parseFlags() options {
 	o := options{}
+	flag.StringVar(&o.buildDir, "build-dir", "", "If provided, this directory will be uploaded as the source for the Google Cloud Build run.")
+	flag.StringVar(&o.cloudbuildFile, "gcb-config", "cloudbuild.yaml", "If provided, this will be used as the name of the Google Cloud Build config file.")
 	flag.StringVar(&o.logDir, "log-dir", "", "If provided, build logs will be sent to files in this directory instead of to stdout/stderr.")
 	flag.StringVar(&o.scratchBucket, "scratch-bucket", "", "The complete GCS path for Cloud Build to store scratch files (sources, logs).")
 	flag.StringVar(&o.project, "project", "", "If specified, use a non-default GCP project.")
 	flag.BoolVar(&o.allowDirty, "allow-dirty", false, "If true, allow pushing dirty builds.")
 	flag.StringVar(&o.variant, "variant", "", "If specified, build only the given variant. An error if no variants are defined.")
-	flag.StringVar(&o.envPassthrough, "env-passthrough", "", "Comma-separated list of specified environment variables to be passed to GCB as subtitutions with an _ prefix. If the variable doesn't exist, the substitution will exist but be empty.")
+	flag.StringVar(&o.envPassthrough, "env-passthrough", "", "Comma-separated list of specified environment variables to be passed to GCB as substitutions with an _ prefix. If the variable doesn't exist, the substitution will exist but be empty.")
+
 	flag.Parse()
+
 	if flag.NArg() < 1 {
-		_, _ = fmt.Fprintln(os.Stderr, "expected an image directory to be provided")
+		_, _ = fmt.Fprintln(os.Stderr, "expected a config directory to be provided")
 		os.Exit(1)
 	}
-	o.imageDirectory = flag.Arg(0)
+
+	o.configDir = strings.TrimSuffix(flag.Arg(0), "/")
+
 	return o
 }
 
 func main() {
 	o := parseFlags()
-	if err := cdToRootDir(); err != nil {
-		log.Fatalf("Failed to cd to root: %v\n", err)
+
+	if bazelWorkspace := os.Getenv("BUILD_WORKSPACE_DIRECTORY"); bazelWorkspace != "" {
+		if err := os.Chdir(bazelWorkspace); err != nil {
+			log.Fatalf("Failed to chdir to bazel workspace (%s): %v", bazelWorkspace, err)
+		}
+	}
+
+	configDirErr := o.validateConfigDir()
+	if configDirErr != nil {
+		log.Fatalf("Could not validate config directory: %v", configDirErr)
+	}
+
+	if o.buildDir != "" {
+		o.cloudbuildFile = path.Join(o.configDir, o.cloudbuildFile)
+	} else {
+		o.buildDir = o.configDir
+	}
+
+	log.Printf("Build directory: %s\n", o.buildDir)
+	log.Printf("Config directory: %s\n", o.configDir)
+
+	log.Printf("cd-ing to build directory: %s\n", o.buildDir)
+	if err := os.Chdir(o.buildDir); err != nil {
+		log.Fatalf("Failed to chdir to build directory (%s): %v", o.buildDir, err)
 	}
 
 	errors := runBuildJobs(o)
 	if len(errors) != 0 {
-		log.Fatalf("Failed to push some images: %v", errors)
+		log.Fatalf("Failed to run some build jobs: %v", errors)
 	}
 	log.Println("Finished.")
 }