Fix injection of gitaly servers info

InjectGitalyServers used `NewOutgoingContext` that completely
overrides all outgoing metadata values, so no values except
'gitaly-servers' were passed with outgoing requests.

Fixed by replacing `NewOutgoingContext` with `AppendToOutgoingContext`
that appends passed values to existing metadata or crete it if
not present.

Closes: https://gitlab.com/gitlab-org/gitaly/-/issues/3158

3 files changed, 47 insertions, 1 deletions

diff --git a/changelogs/unreleased/ps-fix-inject-gitalies.yml b/changelogs/unreleased/ps-fix-inject-gitalies.yml
new file mode 100644
index 000000000..0bdd05b5a
--- /dev/null
+++ b/changelogs/unreleased/ps-fix-inject-gitalies.yml
@@ -0,0 +1,5 @@
+---
+title: Fix injection of gitaly servers info
+merge_request: 2615
+author:
+type: fixed
diff --git a/internal/helper/storage.go b/internal/helper/storage.go
index 523ca7ed6..0a465756f 100644
--- a/internal/helper/storage.go
+++ b/internal/helper/storage.go
@@ -74,5 +74,5 @@ func InjectGitalyServers(ctx context.Context, name, address, token string) (cont
 		return nil, err
 	}
 
-	return metadata.NewOutgoingContext(ctx, metadata.Pairs("gitaly-servers", base64.StdEncoding.EncodeToString(gitalyServersJSON))), nil
+	return metadata.AppendToOutgoingContext(ctx, "gitaly-servers", base64.StdEncoding.EncodeToString(gitalyServersJSON)), nil
 }
diff --git a/internal/helper/storage_test.go b/internal/helper/storage_test.go
index d0f229e0e..1e50e04cd 100644
--- a/internal/helper/storage_test.go
+++ b/internal/helper/storage_test.go
@@ -1,7 +1,10 @@
 package helper
 
 import (
+	"context"
 	"encoding/base64"
+	"encoding/json"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -56,3 +59,41 @@ func TestExtractGitalyServers(t *testing.T) {
 		})
 	}
 }
+
+func TestInjectGitalyServers(t *testing.T) {
+	check := func(t *testing.T, ctx context.Context) {
+		t.Helper()
+
+		newCtx, err := InjectGitalyServers(ctx, "gitaly-1", "1.1.1.1", "secret")
+		require.NoError(t, err)
+
+		md, found := metadata.FromOutgoingContext(newCtx)
+		require.True(t, found)
+
+		gs, found := md["gitaly-servers"]
+		require.True(t, found)
+
+		require.Len(t, gs, 1)
+
+		var servers map[string]interface{}
+		require.NoError(t, json.NewDecoder(base64.NewDecoder(base64.StdEncoding, strings.NewReader(gs[0]))).Decode(&servers), "received %s", gs[0])
+		require.EqualValues(t, map[string]interface{}{"gitaly-1": map[string]interface{}{"address": "1.1.1.1", "token": "secret"}}, servers)
+	}
+
+	t.Run("brand new context", func(t *testing.T) {
+		ctx := context.Background()
+
+		check(t, ctx)
+	})
+
+	t.Run("context with existing outgoing metadata should not be re-written", func(t *testing.T) {
+		existing := metadata.New(map[string]string{"foo": "bar"})
+
+		ctx := metadata.NewOutgoingContext(context.Background(), existing)
+		check(t, ctx)
+
+		md, found := metadata.FromOutgoingContext(ctx)
+		require.True(t, found)
+		require.Equal(t, []string{"bar"}, md["foo"])
+	})
+}