git: allow pushing to an anonymous remote

mhagger · mhagger · commit dd7b094bf37e · 2025-04-13T17:51:01.000+02:00
Git allows you to push to a remote that isn't defined in your gitconfig: git push https://example.com/foo.git refs/heads/bar:refs/heads/bar The effect of this command is to push to the remote repository at the specified URL, without updating any remote-tracking references corresponding to the reference that was pushed. It would seem that this should be possible with `go-git`, by writing something like r, _ := git.PlainOpen(".") _ = r.Push(&git.PushOptions{ RemoteURL: "https://example.com/foo.git", RefSpecs: []config.RefSpec{"refs/heads/bar:refs/heads/bar"}, }) But `go-git` wasn't handling this correctly: * `PushOptions.Validate()` saw the empty `o.RemoteName` and changed it to `DefaultRemoteName` ("origin"). * If no "origin" remote was defined in the gitconfig, `Repository.Push()` failed entirely with `ErrRemoteNotFound`. * If: an "origin" _was_ defined in the gitconfig, then after the push, remote-tracking references were created for the "origin" remote (e.g., `refs/remotes/origin/foo`), even though the push was probably to a remote that is not related to "origin". Alternatively, if the `PushOptions` were created using `RemoteName: "anonymous"`, the push still failed with `ErrRemoteNotFound` because a remote called "anonymous" was sought in the gitconfig, and that remote:(presumably!) doesn't exist. This commit fixes all three problems: * Change the behavior of `PushOptions.Validate()`: if there is a `RemoteURL` but no `RemoteName`, then set the `RemoteName` to `config.AnonymousRemoteName` rather than setting it to `DefaultRemoteName`. (If neither a `RemoteName` nor a `RemoteURL` is set, then set `RemoteName` to `DefaultRemoteName` as before.) * Change `Remote.updateRemoteReferenceStorage()` to skip updating any remote-tracking references if the remote is anonymous.
diff --git a/options.go b/options.go
@@ -310,7 +310,11 @@ type ForceWithLease struct {
 // Validate validates the fields and sets the default values.
 func (o *PushOptions) Validate() error {
 	if o.RemoteName == "" {
-		o.RemoteName = DefaultRemoteName
+		if o.RemoteURL != "" {
+			o.RemoteName = config.AnonymousRemoteName
+		} else {
+			o.RemoteName = DefaultRemoteName
+		}
 	}
 
 	if len(o.RefSpecs) == 0 {
diff --git a/remote.go b/remote.go
@@ -354,9 +354,18 @@ func (r *Remote) newReferenceUpdateRequest(
 	return req, nil
 }
 
+// updateRemoteReferenceStorage updates the remote references
+// corresponding to the references that were just pushed to the
+// remote, if needed.
 func (r *Remote) updateRemoteReferenceStorage(
 	req *packp.ReferenceUpdateRequest,
 ) error {
+	if r.IsAnonymous() {
+		// If the remote is anonymous, then there are no
+		// remote-tracking references corresponding to it.
+		return nil
+	}
+
 	for _, spec := range r.c.Fetch {
 		for _, c := range req.Commands {
 			if !spec.Match(c.Name) {
diff --git a/repository.go b/repository.go
@@ -1249,9 +1249,21 @@ func (r *Repository) PushContext(ctx context.Context, o *PushOptions) error {
 		return err
 	}
 
-	remote, err := r.Remote(o.RemoteName)
-	if err != nil {
-		return err
+	var remote *Remote
+	if o.RemoteName == config.AnonymousRemoteName {
+		var err error
+		remote, err = r.CreateRemoteAnonymous(
+			config.NewAnonymousRemoteConfig(o.RemoteURL),
+		)
+		if err != nil {
+			return err
+		}
+	} else {
+		var err error
+		remote, err = r.Remote(o.RemoteName)
+		if err != nil {
+			return err
+		}
 	}
 
 	return remote.PushContext(ctx, o)
diff --git a/repository_test.go b/repository_test.go
@@ -1680,6 +1680,7 @@ func (s *RepositorySuite) TestCloneWithFilter() {
 	s.NotNil(err)
 	s.Nil(blob)
 }
+
 func (s *RepositorySuite) TestPush() {
 	url, err := os.MkdirTemp("", "")
 	s.NoError(err)
@@ -1709,6 +1710,40 @@ func (s *RepositorySuite) TestPush() {
 	})
 }
 
+func (s *RepositorySuite) TestPushAnonymous() {
+	url, err := os.MkdirTemp("", "")
+	s.NoError(err)
+
+	server, err := PlainInit(url, true)
+	s.NoError(err)
+
+	// Make sure that there is an "origin" remote. It will _not_ be
+	// used, but we want to make sure that its remote-tracking
+	// branches are not incorrectly updated by the push.
+	c, err := s.Repository.Config()
+	s.NoError(err)
+	if _, ok := c.Remotes["origin"]; !ok {
+		// Create an "origin" remote.
+		_, err = s.Repository.CreateRemote(&config.RemoteConfig{
+			Name: "origin",
+			URLs: []string{filepath.Join(url, "origin-not-used")},
+		})
+		s.NoError(err)
+	}
+
+	err = s.Repository.Push(&PushOptions{
+		RemoteURL: url,
+	})
+	s.NoError(err)
+
+	AssertReferences(s.T(), server, map[string]string{
+		"refs/heads/master": "6ecf0ef2c2dffb796033e5a02219af86ec6584e5",
+		"refs/heads/branch": "e8d3ffab552895c19b9fcf7aa264d277cde33881",
+	})
+
+	AssertReferences(s.T(), s.Repository, map[string]string{})
+}
+
 func (s *RepositorySuite) TestPushContext() {
 	url, err := os.MkdirTemp("", "")
 	s.NoError(err)
