build: return ExecErrorCodeGeneric when git operation fails

Only propagate error message from git and let buildah reflect error code
`125`.

Reason: Buildah should return predicatable error code from the set of
defined error codes in exec_codes.go at https://github.com/containers/buildah/blob/main/pkg/cli/exec_codes.go#L6
anything other that predefined error codes introduces inconsistency thus making testing difficult in CI and podman.

Users should expect buildah to refect ExecErrorCodeGeneric with error message kept intact from the underlying `git`
commands.

Signed-off-by: flouthoc <[email protected]>

Author: flouthoc

define/types.go

@@ -267,14 +267,18 @@ func cloneToDirectory(url, dir string) ([]byte, string, error) {
 	cmd = exec.Command("git", "init", dir)
 	combinedOutput, err := cmd.CombinedOutput()
 	if err != nil {
-		return combinedOutput, gitSubdir, fmt.Errorf("failed while performing `git init`: %w", err)
+		// Return err.Error() instead of err as we want buildah to override error code with more predictable
+		// value.
+		return combinedOutput, gitSubdir, fmt.Errorf("failed while performing `git init`: %s", err.Error())
 	}
 	// add origin
 	cmd = exec.Command("git", "remote", "add", "origin", gitRepo)
 	cmd.Dir = dir
 	combinedOutput, err = cmd.CombinedOutput()
 	if err != nil {
-		return combinedOutput, gitSubdir, fmt.Errorf("failed while performing `git remote add`: %w", err)
+		// Return err.Error() instead of err as we want buildah to override error code with more predictable
+		// value.
+		return combinedOutput, gitSubdir, fmt.Errorf("failed while performing `git remote add`: %s", err.Error())
 	}
 
 	logrus.Debugf("fetching repo %q and branch (or commit ID) %q to %q", gitRepo, gitRef, dir)
@@ -283,14 +287,18 @@ func cloneToDirectory(url, dir string) ([]byte, string, error) {
 	cmd.Dir = dir
 	combinedOutput, err = cmd.CombinedOutput()
 	if err != nil {
-		return combinedOutput, gitSubdir, fmt.Errorf("failed while performing `git fetch`: %w", err)
+		// Return err.Error() instead of err as we want buildah to override error code with more predictable
+		// value.
+		return combinedOutput, gitSubdir, fmt.Errorf("failed while performing `git fetch`: %s", err.Error())
 	}
 
 	cmd = exec.Command("git", "checkout", "FETCH_HEAD")
 	cmd.Dir = dir
 	combinedOutput, err = cmd.CombinedOutput()
 	if err != nil {
-		return combinedOutput, gitSubdir, fmt.Errorf("failed while performing `git checkout`: %w", err)
+		// Return err.Error() instead of err as we want buildah to override error code with more predictable
+		// value.
+		return combinedOutput, gitSubdir, fmt.Errorf("failed while performing `git checkout`: %s", err.Error())
 	}
 	return combinedOutput, gitSubdir, nil
 }

tests/bud.bats

@@ -2919,13 +2919,13 @@ function validate_instance_compression {
 
 @test "bud-git-context-failure" {
   # We need git to be around to try cloning a repository, even though it'll fail
-  # and exit with return code 128.
+  # and buildah will exit with return code 125.
   if ! which git ; then
     skip "no git in PATH"
   fi
   target=giturl-image
   gitrepo=git:///tmp/no-such-repository
-  run_buildah 128 build $WITH_POLICY_JSON -t ${target} "${gitrepo}"
+  run_buildah 125 build $WITH_POLICY_JSON -t ${target} "${gitrepo}"
   # Expect part of what git would have told us... before things went horribly wrong
   expect_output --substring "failed while performing"
   expect_output --substring "git fetch"
@@ -7318,7 +7318,7 @@ _EOF
 FROM scratch
 ADD https://github.com/containers/crun.git#nosuchbranch /src
 _EOF
-  run_buildah 128 build -f $contextdir/Dockerfile -t git-image $contextdir
+  run_buildah 125 build -f $contextdir/Dockerfile -t git-image $contextdir
   expect_output --substring "couldn't find remote ref nosuchbranch"
 }