fix: ignore gitlab projects w/o repository (#12819) (cherry-pick #12820)

USERS.md

@@ -188,6 +188,7 @@ Currently, the following organizations are **officially** using Argo CD:
 1. [RapidAPI](https://www.rapidapi.com/)
 1. [Recreation.gov](https://www.recreation.gov/)
 1. [Red Hat](https://www.redhat.com/)
+1. [Redpill Linpro](https://www.redpill-linpro.com/)
 1. [reev.com](https://www.reev.com/)
 1. [RightRev](https://rightrev.com/)
 1. [Rise](https://www.risecard.eu/)

applicationset/services/scm_provider/gitlab.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"os"
+	"net/http"
 	pathpkg "path"
 
 	gitlab "github.com/xanzy/go-gitlab"
@@ -144,7 +145,11 @@ func (g *GitlabProvider) listBranches(_ context.Context, repo *Repository) ([]gi
 	branches := []gitlab.Branch{}
 	// If we don't specifically want to query for all branches, just use the default branch and call it a day.
 	if !g.allBranches {
-		gitlabBranch, _, err := g.client.Branches.GetBranch(repo.RepositoryId, repo.Branch, nil)
+		gitlabBranch, resp, err := g.client.Branches.GetBranch(repo.RepositoryId, repo.Branch, nil)
+		// 404s are not an error here, just a normal false.
+		if resp != nil && resp.StatusCode == http.StatusNotFound {
+			return []gitlab.Branch{}, nil
+		}
 		if err != nil {
 			return nil, err
 		}
@@ -157,6 +162,10 @@ func (g *GitlabProvider) listBranches(_ context.Context, repo *Repository) ([]gi
 	}
 	for {
 		gitlabBranches, resp, err := g.client.Branches.ListBranches(repo.RepositoryId, opt)
+		// 404s are not an error here, just a normal false.
+		if resp != nil && resp.StatusCode == http.StatusNotFound {
+			return []gitlab.Branch{}, nil
+		}
 		if err != nil {
 			return nil, err
 		}

applicationset/services/scm_provider/gitlab_test.go

@@ -274,6 +274,8 @@ func gitlabMockHandler(t *testing.T) func(http.ResponseWriter, *http.Request) {
 			if err != nil {
 				t.Fail()
 			}
+		case "/api/v4/projects/27084533/repository/branches/foo":
+			w.WriteHeader(http.StatusNotFound)
 		default:
 			_, err := io.WriteString(w, `[]`)
 			if err != nil {
@@ -391,3 +393,29 @@ func TestGitlabHasPath(t *testing.T) {
 		})
 	}
 }
+
+func TestGitlabGetBranches(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		gitlabMockHandler(t)(w, r)
+	}))
+	host, _ := NewGitlabProvider(context.Background(), "test-argocd-proton", "", ts.URL, false, true)
+
+	repo := &Repository{
+		RepositoryId: 27084533,
+		Branch:       "master",
+	}
+	t.Run("branch exists", func(t *testing.T) {
+		repos, err := host.GetBranches(context.Background(), repo)
+		assert.Nil(t, err)
+		assert.Equal(t, repos[0].Branch, "master")
+	})
+
+	repo2 := &Repository{
+		RepositoryId: 27084533,
+		Branch:       "foo",
+	}
+	t.Run("unknown branch", func(t *testing.T) {
+		_, err := host.GetBranches(context.Background(), repo2)
+		assert.NoError(t, err)
+	})
+}