Make it possible to propagate correlation ID across processes

Previously, gitlab-shell did not pass a context through the application.
Correlation IDs were generated down the call stack instead of passed
around from the start execution.

This has several potential downsides:

1. It's easier for programming mistakes to be made in future that lead
to multiple correlation IDs being generated for a single request.
2. Correlation IDs cannot be passed in from upstream requests
3. Other advantages of context passing, such as distributed tracing is
not possible.

This commit changes the behavior:

1. Extract the correlation ID from the environment at the start of
the application.
2. If no correlation ID exists, generate a random one.
3. Pass the correlation ID to the GitLabNet API requests.

This change also enables other clients of GitLabNet (e.g. Gitaly) to
pass along the correlation ID in the internal API requests
(https://gitlab.com/gitlab-org/gitaly/-/issues/2725).

Fixes https://gitlab.com/gitlab-org/gitlab-shell/-/issues/474

1 files changed, 7 insertions, 5 deletions

diff --git a/internal/command/uploadpack/uploadpack.go b/internal/command/uploadpack/uploadpack.go
index 56814d7..fca3823 100644
--- a/internal/command/uploadpack/uploadpack.go
+++ b/internal/command/uploadpack/uploadpack.go
@@ -1,6 +1,8 @@
 package uploadpack
 
 import (
+	"context"
+
 	"gitlab.com/gitlab-org/gitlab-shell/internal/command/commandargs"
 	"gitlab.com/gitlab-org/gitlab-shell/internal/command/readwriter"
 	"gitlab.com/gitlab-org/gitlab-shell/internal/command/shared/accessverifier"
@@ -15,14 +17,14 @@ type Command struct {
 	ReadWriter *readwriter.ReadWriter
 }
 
-func (c *Command) Execute() error {
+func (c *Command) Execute(ctx context.Context) error {
 	args := c.Args.SshArgs
 	if len(args) != 2 {
 		return disallowedcommand.Error
 	}
 
 	repo := args[1]
-	response, err := c.verifyAccess(repo)
+	response, err := c.verifyAccess(ctx, repo)
 	if err != nil {
 		return err
 	}
@@ -33,14 +35,14 @@ func (c *Command) Execute() error {
 			ReadWriter: c.ReadWriter,
 			EOFSent:    false,
 		}
-		return customAction.Execute(response)
+		return customAction.Execute(ctx, response)
 	}
 
 	return c.performGitalyCall(response)
 }
 
-func (c *Command) verifyAccess(repo string) (*accessverifier.Response, error) {
+func (c *Command) verifyAccess(ctx context.Context, repo string) (*accessverifier.Response, error) {
 	cmd := accessverifier.Command{c.Config, c.Args, c.ReadWriter}
 
-	return cmd.Verify(c.Args.CommandType, repo)
+	return cmd.Verify(ctx, c.Args.CommandType, repo)
 }