bazel-deps-mirror: upgrade command (#1617)

* bazel-deps-mirror: upgrade command

This command can be used to upgrade a dependency.
Users are supposed to replace any upstream URLs and run the upgrade command.
It replaces the expected hash and uploads the new dep to the mirror.

hack/bazel-deps-mirror/fix.go

@@ -131,41 +131,72 @@ func fixBazelFile(ctx context.Context, fileHelper *bazelfiles.Helper, mirrorUplo
 	return iss, nil
 }
 
+func learnHashForRule(ctx context.Context, mirrorUpload mirrorUploader, rule *build.Rule, log *logger.Logger) error {
+	upstreamURLs, err := rules.UpstreamURLs(rule)
+	if err != nil {
+		return err
+	}
+	learnedHash, learnErr := mirrorUpload.Learn(ctx, upstreamURLs)
+	if learnErr != nil {
+		return err
+	}
+	rules.SetHash(rule, learnedHash)
+	log.Debugf("Learned hash for rule %s: %s", rule.Name(), learnedHash)
+	return nil
+}
+
 func fixRule(ctx context.Context, mirrorUpload mirrorUploader, rule *build.Rule, log *logger.Logger) (changed bool, iss []error) {
 	log.Debugf("Fixing rule: %s", rule.Name())
+
+	// try to learn the hash
+	if hash, err := rules.GetHash(rule); err != nil || hash == "" {
+		if err := learnHashForRule(ctx, mirrorUpload, rule, log); err != nil {
+			// don't try to fix the rule if the hash is missing and we can't learn it
+			iss = append(iss,
+				errors.New("hash attribute is missing and can't learn it from upstream."+
+					"Unable to check if the artifact is already mirrored or upload it"))
+			return false, iss
+		}
+		changed = true
+	}
+
 	// check if the rule is a valid pinned dependency rule (has all required attributes)
 	issue := rules.ValidatePinned(rule)
 	if issue != nil {
 		// don't try to fix the rule if it's invalid
 		iss = append(iss, issue...)
-		return
+		return false, iss
 	}
 
 	// check if the referenced CAS object exists in the mirror and is consistent
 	expectedHash, expectedHashErr := rules.GetHash(rule)
 	if expectedHashErr != nil {
 		// don't try to fix the rule if the hash is missing
-		iss = append(iss,
-			errors.New("hash attribute is missing. unable to check if the artifact is already mirrored or upload it"))
-		return
+		iss = append(iss, expectedHashErr)
+		return false, iss
 	}
 
 	if rules.HasMirrorURL(rule) {
-		changed = rules.Normalize(rule)
-		return
+		changed = rules.Normalize(rule) || changed
+		return changed, iss
 	}
 
-	log.Infof("Artifact %s with hash %s is not yet mirrored. Uploading...", rule.Name(), expectedHash)
-	if uploadErr := mirrorUpload.Mirror(ctx, expectedHash, rules.GetURLs(rule)); uploadErr != nil {
-		// don't try to fix the rule if the upload failed
-		iss = append(iss, uploadErr)
-		return
+	if checkErr := mirrorUpload.Check(ctx, expectedHash); checkErr != nil {
+		log.Infof("Artifact %s with hash %s is not yet mirrored. Uploading...", rule.Name(), expectedHash)
+		if uploadErr := mirrorUpload.Mirror(ctx, expectedHash, rules.GetURLs(rule)); uploadErr != nil {
+			// don't try to fix the rule if the upload failed
+			iss = append(iss, uploadErr)
+			return changed, iss
+		}
+	} else {
+		log.Infof("Artifact %s with hash %s was already uploaded before. Adding to rule...", rule.Name(), expectedHash)
 	}
+
 	// now the artifact is mirrored (if it wasn't already) and we can fix the rule
 	mirrorURL, err := mirrorUpload.MirrorURL(expectedHash)
 	if err != nil {
 		iss = append(iss, err)
-		return
+		return changed, iss
 	}
 	rules.AddURLs(rule, []string{mirrorURL})
 
@@ -224,6 +255,7 @@ func parseFixFlags(cmd *cobra.Command) (fixFlags, error) {
 }
 
 type mirrorUploader interface {
+	Learn(ctx context.Context, urls []string) (string, error)
 	Check(ctx context.Context, expectedHash string) error
 	Mirror(ctx context.Context, hash string, urls []string) error
 	MirrorURL(hash string) (string, error)