gogit: Add new ForceGoGitImplementation FeatureGate

ForceGoGitImplementation ignores the value set for gitImplementation
and ensures that go-git is used for all GitRepository objects.
This can be used to confirm that Flux instances won't break if/when
the libgit2 implementation was to be deprecated.

When enabled, libgit2 won't be initialized, nor will any git2go cgo
code be called.

Signed-off-by: Paulo Gomes <paulo.gomes@weave.works>

controllers/gitrepository_controller.go

@@ -427,8 +427,13 @@ func (r *GitRepositoryReconciler) reconcileStorage(ctx context.Context,
 // change, it short-circuits the whole reconciliation with an early return.
 func (r *GitRepositoryReconciler) reconcileSource(ctx context.Context,
  obj *sourcev1.GitRepository, commit *git.Commit, includes *artifactSet, dir string) (sreconcile.Result, error) {
+ gitImplementation := obj.Spec.GitImplementation
+ if enabled, _ := r.features[features.ForceGoGitImplementation]; enabled {
+ gitImplementation = sourcev1.GoGitImplementation
+ }
+
  // Exit early, if we need to use libgit2 AND managed transport hasn't been intialized.
- if !r.Libgit2TransportInitialized() && obj.Spec.GitImplementation == sourcev1.LibGit2Implementation {
+ if !r.Libgit2TransportInitialized() && gitImplementation == sourcev1.LibGit2Implementation {
  return sreconcile.ResultEmpty, serror.NewStalling(
  errors.New("libgit2 managed transport not initialized"), "Libgit2TransportNotEnabled",
  )
@@ -758,18 +763,23 @@ func (r *GitRepositoryReconciler) gitCheckout(ctx context.Context,
  var gitReader git.RepositoryReader
  var err error
 
- switch obj.Spec.GitImplementation {
+ gitImplementation := obj.Spec.GitImplementation
+ if enabled, _ := r.features[features.ForceGoGitImplementation]; enabled {
+ gitImplementation = sourcev1.GoGitImplementation
+ }
+
+ switch gitImplementation {
  case sourcev1.LibGit2Implementation:
  gitReader, err = libgit2.NewClient(dir, authOpts)
  case sourcev1.GoGitImplementation:
  gitReader, err = gogit.NewClient(dir, authOpts)
  default:
- err = fmt.Errorf("invalid Git implementation: %s", obj.Spec.GitImplementation)
+ err = fmt.Errorf("invalid Git implementation: %s", gitImplementation)
  }
  if err != nil {
  // Do not return err as recovery without changes is impossible.
  e := serror.NewStalling(
- fmt.Errorf("failed to create Git client for implementation '%s': %w", obj.Spec.GitImplementation, err),
+ fmt.Errorf("failed to create Git client for implementation '%s': %w", gitImplementation, err),
  sourcev1.GitOperationFailedReason,
  )
  conditions.MarkTrue(obj, sourcev1.FetchFailedCondition, e.Reason, e.Err.Error())

controllers/gitrepository_controller_test.go

@@ -498,10 +498,12 @@ func TestGitRepositoryReconciler_reconcileSource_authStrategy(t *testing.T) {
  }
 
  r := &GitRepositoryReconciler{
- Client: builder.Build(),
- EventRecorder: record.NewFakeRecorder(32),
- Storage: testStorage,
- features: features.FeatureGates(),
+ Client: builder.Build(),
+ EventRecorder: record.NewFakeRecorder(32),
+ Storage: testStorage,
+ features: map[string]bool{
+ features.ForceGoGitImplementation: false,
+ },
  Libgit2TransportInitialized: transport.Enabled,
  }
 
@@ -543,10 +545,12 @@ func TestGitRepositoryReconciler_reconcileSource_libgit2TransportUninitialized(t
  g := NewWithT(t)
 
  r := &GitRepositoryReconciler{
- Client: fakeclient.NewClientBuilder().WithScheme(runtime.NewScheme()).Build(),
- EventRecorder: record.NewFakeRecorder(32),
- Storage: testStorage,
- features: features.FeatureGates(),
+ Client: fakeclient.NewClientBuilder().WithScheme(runtime.NewScheme()).Build(),
+ EventRecorder: record.NewFakeRecorder(32),
+ Storage: testStorage,
+ features: map[string]bool{
+ features.ForceGoGitImplementation: false,
+ },
  Libgit2TransportInitialized: mockTransportNotInitialized,
  }
 
@@ -727,10 +731,12 @@ func TestGitRepositoryReconciler_reconcileSource_checkoutStrategy(t *testing.T)
  }
 
  r := &GitRepositoryReconciler{
- Client: fakeclient.NewClientBuilder().WithScheme(runtime.NewScheme()).Build(),
- EventRecorder: record.NewFakeRecorder(32),
- Storage: testStorage,
- features: features.FeatureGates(),
+ Client: fakeclient.NewClientBuilder().WithScheme(runtime.NewScheme()).Build(),
+ EventRecorder: record.NewFakeRecorder(32),
+ Storage: testStorage,
+ features: map[string]bool{
+ features.ForceGoGitImplementation: false,
+ },
  Libgit2TransportInitialized: transport.Enabled,
  }
 

internal/features/features.go

@@ -30,12 +30,21 @@ const (
  // the last revision is still the same at the target repository,
  // and if that is so, skips the reconciliation.
  OptimizedGitClones = "OptimizedGitClones"
+ // ForceGoGitImplementation ignores the value set for gitImplementation
+ // and ensures that go-git is used for all GitRepository objects.
+ //
+ // When enabled, libgit2 won't be initialized, nor will any git2go cgo
+ // code be called.
+ ForceGoGitImplementation = "ForceGoGitImplementation"
 )
 
 var features = map[string]bool{
  // OptimizedGitClones
  // opt-out from v0.25
  OptimizedGitClones: true,
+ // ForceGoGitImplementation
+ // opt-in from v0.32
+ ForceGoGitImplementation: true,
 }
 
 // DefaultFeatureGates contains a list of all supported feature gates and

main.go

@@ -204,9 +204,11 @@ func main() {
  }
  storage := mustInitStorage(storagePath, storageAdvAddr, artifactRetentionTTL, artifactRetentionRecords, setupLog)
 
- if err = transport.InitManagedTransport(); err != nil {
- // Log the error, but don't exit so as to not block reconcilers that are healthy.
- setupLog.Error(err, "unable to initialize libgit2 managed transport")
+ if gogitOnly, _ := features.Enabled(features.ForceGoGitImplementation); !gogitOnly {
+ if err = transport.InitManagedTransport(); err != nil {
+ // Log the error, but don't exit so as to not block reconcilers that are healthy.
+ setupLog.Error(err, "unable to initialize libgit2 managed transport")
+ }
  }
 
  if err = (&controllers.GitRepositoryReconciler{