gitaly: Move Gitaly-specific code into `internal/gitaly`

Since the introduction of Praefect, our code layout started to become
confusing: while Praefect code lives in `internal/praefect`,
Gitaly-specific code is all over the place and not neatly singled out.
This makes it hard at times to tell apart Praefect- and Gitaly-specific
from generic code.

To improve the situation, this commit thus moves most of the server
specific code into a new `internal/gitaly` package. Currently, this is
the `internal/config`, `internal/server`, `internal/service` and
`internal/rubyserver` packages, which are all main components of Gitaly.
The move was realized with the following script:

    #!/bin/sh
    mkdir -p internal/gitaly
    git mv internal/{config,server,service,rubyserver} internal/gitaly/
    find . -name '*.go' -exec sed -i \
        -e 's|gitlab-org/gitaly/internal/rubyserver|gitlab-org/gitaly/internal/gitaly/rubyserver|' \
        -e 's|gitlab-org/gitaly/internal/server|gitlab-org/gitaly/internal/gitaly/server|' \
        -e 's|gitlab-org/gitaly/internal/service|gitlab-org/gitaly/internal/gitaly/service|' \
        -e 's|gitlab-org/gitaly/internal/config|gitlab-org/gitaly/internal/gitaly/config|' {} \;

In addition to that, some minor adjustments were needed for tests which
used relative paths.

1 files changed, 84 insertions, 0 deletions

diff --git a/internal/gitaly/service/repository/fetch.go b/internal/gitaly/service/repository/fetch.go
new file mode 100644
index 000000000..cb27a9bc7
--- /dev/null
+++ b/internal/gitaly/service/repository/fetch.go
@@ -0,0 +1,84 @@
+package repository
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/grpc-ecosystem/go-grpc-middleware/logging/logrus/ctxlogrus"
+	"gitlab.com/gitlab-org/gitaly/internal/git"
+	"gitlab.com/gitlab-org/gitaly/internal/gitaly/rubyserver"
+	"gitlab.com/gitlab-org/gitaly/internal/gitalyssh"
+	"gitlab.com/gitlab-org/gitaly/internal/helper"
+	"gitlab.com/gitlab-org/gitaly/internal/metadata/featureflag"
+	"gitlab.com/gitlab-org/gitaly/proto/go/gitalypb"
+)
+
+func (s *server) FetchSourceBranch(ctx context.Context, req *gitalypb.FetchSourceBranchRequest) (*gitalypb.FetchSourceBranchResponse, error) {
+	if featureflag.IsDisabled(ctx, featureflag.GoFetchSourceBranch) {
+		return s.rubyFetchSourceBranch(ctx, req)
+	}
+
+	if err := git.ValidateRevision(req.GetSourceBranch()); err != nil {
+		return nil, helper.ErrInvalidArgument(err)
+	}
+
+	if err := git.ValidateRevision(req.GetTargetRef()); err != nil {
+		return nil, helper.ErrInvalidArgument(err)
+	}
+
+	repoPath, err := helper.GetRepoPath(req.Repository)
+	if err != nil {
+		return nil, err
+	}
+
+	refspec := fmt.Sprintf("%s:%s", req.GetSourceBranch(), req.GetTargetRef())
+
+	var remote string
+	var env []string
+	if helper.RepoPathEqual(req.GetRepository(), req.GetSourceRepository()) {
+		remote = "file://" + repoPath
+	} else {
+		remote = gitalyInternalURL
+		env, err = gitalyssh.UploadPackEnv(ctx, &gitalypb.SSHUploadPackRequest{Repository: req.SourceRepository})
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	cmd, err := git.SafeBareCmd(ctx, git.CmdStream{}, env,
+		[]git.Option{git.ValueFlag{"--git-dir", repoPath}},
+		git.SubCmd{
+			Name:  "fetch",
+			Flags: []git.Option{git.Flag{Name: "--prune"}},
+			Args:  []string{remote, refspec},
+		},
+	)
+	if err != nil {
+		return nil, err
+	}
+	if err := cmd.Wait(); err != nil {
+		// Design quirk: if the fetch fails, this RPC returns Result: false, but no error.
+		ctxlogrus.Extract(ctx).
+			WithField("repo_path", repoPath).
+			WithField("remote", remote).
+			WithField("refspec", refspec).
+			WithError(err).Warn("git fetch failed")
+		return &gitalypb.FetchSourceBranchResponse{Result: false}, nil
+	}
+
+	return &gitalypb.FetchSourceBranchResponse{Result: true}, nil
+}
+
+func (s *server) rubyFetchSourceBranch(ctx context.Context, req *gitalypb.FetchSourceBranchRequest) (*gitalypb.FetchSourceBranchResponse, error) {
+	client, err := s.ruby.RepositoryServiceClient(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	clientCtx, err := rubyserver.SetHeaders(ctx, req.GetRepository())
+	if err != nil {
+		return nil, err
+	}
+
+	return client.FetchSourceBranch(clientCtx, req)
+}