From ec8e352af570339c7dd433fe73cfba4f63874004 Mon Sep 17 00:00:00 2001
From: yuchanns <me@yuchanns.xyz>
Date: Fri, 21 Oct 2022 17:52:49 +0800
Subject: [PATCH] Support `nerdctl build` custom outputs alias of type local

Signed-off-by: Hanchin Hsieh <me@yuchanns.xyz>
---
 cmd/nerdctl/build.go      |  5 +++++
 cmd/nerdctl/build_test.go | 14 +++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/cmd/nerdctl/build.go b/cmd/nerdctl/build.go
index 42fddfd1ae6..1035e4ade1c 100644
--- a/cmd/nerdctl/build.go
+++ b/cmd/nerdctl/build.go
@@ -290,6 +290,11 @@ func generateBuildctlArgs(cmd *cobra.Command, buildkitHost string, platform, arg
 			needsLoading = true
 		}
 	} else {
+		if !strings.Contains(output, "type=") {
+			// should accept --output <DIR> as an alias of --output
+			// type=local,dest=<DIR>
+			output = fmt.Sprintf("type=local,dest=%s", output)
+		}
 		if strings.Contains(output, "type=docker") || strings.Contains(output, "type=oci") {
 			needsLoading = true
 		}
diff --git a/cmd/nerdctl/build_test.go b/cmd/nerdctl/build_test.go
index 25092f287b1..fcb9812b0e7 100644
--- a/cmd/nerdctl/build_test.go
+++ b/cmd/nerdctl/build_test.go
@@ -174,9 +174,11 @@ CMD ["echo", "nerdctl-build-test-dockerfile"]
 
 func TestBuildLocal(t *testing.T) {
 	t.Parallel()
-	testutil.DockerIncompatible(t)
 	testutil.RequiresBuild(t)
 	base := testutil.NewBase(t)
+	if testutil.GetTarget() == testutil.Docker {
+		base.Env = append(base.Env, "DOCKER_BUILDKIT=1")
+	}
 	defer base.Cmd("builder", "prune").Run()
 	const testFileName = "nerdctl-build-test"
 	const testContent = "nerdctl"
@@ -202,6 +204,16 @@ COPY %s /`,
 	data, err := os.ReadFile(testFilePath)
 	assert.NilError(t, err)
 	assert.Equal(t, string(data), testContent)
+
+	aliasOutputDir := t.TempDir()
+	testAliasFilePath := filepath.Join(aliasOutputDir, testFileName)
+	base.Cmd("build", "-o", aliasOutputDir, buildCtx).AssertOK()
+	if _, err := os.Stat(testAliasFilePath); err != nil {
+		t.Fatal(err)
+	}
+	data, err = os.ReadFile(testAliasFilePath)
+	assert.NilError(t, err)
+	assert.Equal(t, string(data), testContent)
 }
 
 func createBuildContext(dockerfile string) (string, error) {