From c84179088cf3abd15160ddead9da000482a580e1 Mon Sep 17 00:00:00 2001
From: Paulo Gomes <paulo.gomes@weave.works>
Date: Tue, 29 Mar 2022 23:11:02 +0100
Subject: [PATCH] Fixes regression accessing GitLab public repositories

Some git servers are more accommodating than others. Gitlab will try to
validate credentials when they are provided, even if they are empty and
the target repository is public, leading to a failed authentication error.

Signed-off-by: Paulo Gomes <paulo.gomes@weave.works>
---
 pkg/git/gogit/transport.go      | 13 +++++++++----
 pkg/git/gogit/transport_test.go | 18 ++++++++++++++++++
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/pkg/git/gogit/transport.go b/pkg/git/gogit/transport.go
index 0ab3fbd6..cd59110d 100644
--- a/pkg/git/gogit/transport.go
+++ b/pkg/git/gogit/transport.go
@@ -36,10 +36,15 @@ func transportAuth(opts *git.AuthOptions) (transport.AuthMethod, error) {
 	}
 	switch opts.Transport {
 	case git.HTTPS, git.HTTP:
-		return &http.BasicAuth{
-			Username: opts.Username,
-			Password: opts.Password,
-		}, nil
+		// Some providers (i.e. GitLab) will reject empty credentials for
+		// public repositories.
+		if opts.Username != "" || opts.Password != "" {
+			return &http.BasicAuth{
+				Username: opts.Username,
+				Password: opts.Password,
+			}, nil
+		}
+		return nil, nil
 	case git.SSH:
 		if len(opts.Identity) > 0 {
 			pk, err := ssh.NewPublicKeys(opts.Username, opts.Identity, opts.Password)
diff --git a/pkg/git/gogit/transport_test.go b/pkg/git/gogit/transport_test.go
index 93ea279d..43577d9b 100644
--- a/pkg/git/gogit/transport_test.go
+++ b/pkg/git/gogit/transport_test.go
@@ -74,6 +74,24 @@ func Test_transportAuth(t *testing.T) {
 		wantFunc func(g *WithT, t transport.AuthMethod, opts *git.AuthOptions)
 		wantErr  error
 	}{
+		{
+			name: "Public HTTP Repositories",
+			opts: &git.AuthOptions{
+				Transport: git.HTTP,
+			},
+			wantFunc: func(g *WithT, t transport.AuthMethod, opts *git.AuthOptions) {
+				g.Expect(t).To(BeNil())
+			},
+		},
+		{
+			name: "Public HTTPS Repositories",
+			opts: &git.AuthOptions{
+				Transport: git.HTTP,
+			},
+			wantFunc: func(g *WithT, t transport.AuthMethod, opts *git.AuthOptions) {
+				g.Expect(t).To(BeNil())
+			},
+		},
 		{
 			name: "HTTP basic auth",
 			opts: &git.AuthOptions{