From 497d803824a26bc5e6bf1e358a5ada996f46c2c0 Mon Sep 17 00:00:00 2001
From: Hamish <hamish@black.ai>
Date: Mon, 16 Dec 2024 22:20:08 +1100
Subject: [PATCH] Added the ability to specify build targets for kaniko build
 and an option to skip building unused layers

---
 devcontainer/devcontainer.go    |  2 ++
 docs/env-variables.md           |  1 +
 envbuilder.go                   |  2 ++
 options/options.go              | 12 ++++++++++++
 options/testdata/options.golden |  4 ++++
 5 files changed, 21 insertions(+)

diff --git a/devcontainer/devcontainer.go b/devcontainer/devcontainer.go
index 0bf7cc3..4ae8b61 100644
--- a/devcontainer/devcontainer.go
+++ b/devcontainer/devcontainer.go
@@ -69,6 +69,7 @@ type Compiled struct {
 	BuildContext      string
 	FeatureContexts   map[string]string
 	BuildArgs         []string
+	Target			  string
 
 	User         string
 	ContainerEnv map[string]string
@@ -140,6 +141,7 @@ func (s Spec) HasDockerfile() bool {
 func (s *Spec) Compile(fs billy.Filesystem, devcontainerDir, scratchDir string, fallbackDockerfile, workspaceFolder string, useBuildContexts bool, lookupEnv func(string) (string, bool)) (*Compiled, error) {
 	params := &Compiled{
 		User:         s.ContainerUser,
+		Target:       s.Build.Target,
 		ContainerEnv: s.ContainerEnv,
 		RemoteEnv:    s.RemoteEnv,
 	}
diff --git a/docs/env-variables.md b/docs/env-variables.md
index 861f31b..889af06 100644
--- a/docs/env-variables.md
+++ b/docs/env-variables.md
@@ -24,6 +24,7 @@
 | `--ignore-paths` | `ENVBUILDER_IGNORE_PATHS` |  | The comma separated list of paths to ignore when building the workspace. |
 | `--build-secrets` | `ENVBUILDER_BUILD_SECRETS` |  | The list of secret environment variables to use when building the image. |
 | `--skip-rebuild` | `ENVBUILDER_SKIP_REBUILD` |  | Skip building if the MagicFile exists. This is used to skip building when a container is restarting. e.g. docker stop -> docker start This value can always be set to true - even if the container is being started for the first time. |
+| `--skip-unused-stages` | `ENVBUILDER_SKIP_UNUSED_STAGES` |  | Skip building all unused docker stages. Otherwise it builds by default all stages, even the unnecessary ones until it reaches the target stage / end of Dockerfile. |
 | `--git-url` | `ENVBUILDER_GIT_URL` |  | The URL of a Git repository containing a Devcontainer or Docker image to clone. This is optional. |
 | `--git-clone-depth` | `ENVBUILDER_GIT_CLONE_DEPTH` |  | The depth to use when cloning the Git repository. |
 | `--git-clone-single-branch` | `ENVBUILDER_GIT_CLONE_SINGLE_BRANCH` |  | Clone only a single branch of the Git repository. |
diff --git a/envbuilder.go b/envbuilder.go
index ad2c84f..29345f8 100644
--- a/envbuilder.go
+++ b/envbuilder.go
@@ -539,6 +539,8 @@ func run(ctx context.Context, opts options.Options, execArgs *execArgsInfo) erro
 				CustomPlatform:     platforms.Format(platforms.Normalize(platforms.DefaultSpec())),
 				SnapshotMode:       "redo",
 				RunV2:              true,
+				SkipUnusedStages:   opts.SkipUnusedStages,
+				Target:				buildParams.Target,
 				RunStdout:          stdoutWriter,
 				RunStderr:          stderrWriter,
 				Destinations:       destinations,
diff --git a/options/options.go b/options/options.go
index c2b6efe..e4121fb 100644
--- a/options/options.go
+++ b/options/options.go
@@ -100,6 +100,10 @@ type Options struct {
 	// This value can always be set to true - even if the container is being
 	// started for the first time.
 	SkipRebuild bool
+	// SkipUnusedStages builds only used stages if defined to true. Otherwise,
+	// it builds by default all stages, even the unnecessary ones until it
+	// reaches the target stage / end of Dockerfile
+	SkipUnusedStages bool
 	// GitURL is the URL of the Git repository to clone. This is optional.
 	GitURL string
 	// GitCloneDepth is the depth to use when cloning the Git repository.
@@ -357,6 +361,14 @@ func (o *Options) CLI() serpent.OptionSet {
 				"docker start This value can always be set to true - even if the " +
 				"container is being started for the first time.",
 		},
+		{
+			Flag:  "skip-unused-stages",
+			Env:   WithEnvPrefix("SKIP_UNUSED_STAGES"),
+			Value: serpent.BoolOf(&o.SkipUnusedStages),
+			Description: "Skip building all unused docker stages. Otherwise it builds by " +
+				"default all stages, even the unnecessary ones until it reaches the " +
+				"target stage / end of Dockerfile.",
+		},
 		{
 			Flag:        "git-url",
 			Env:         WithEnvPrefix("GIT_URL"),
diff --git a/options/testdata/options.golden b/options/testdata/options.golden
index 6a8145a..b03a633 100644
--- a/options/testdata/options.golden
+++ b/options/testdata/options.golden
@@ -173,6 +173,10 @@ OPTIONS:
           when a container is restarting. e.g. docker stop -> docker start This
           value can always be set to true - even if the container is being
           started for the first time.
+      --skip-unused-stages bool, $ENVBUILDER_SKIP_UNUSED_STAGES
+         Skip building all unused docker stages. Otherwise it builds by default
+          all stages, even the unnecessary ones until it reaches the target
+          stage / end of Dockerfile.
 
       --ssl-cert-base64 string, $ENVBUILDER_SSL_CERT_BASE64
           The content of an SSL cert file. This is useful for self-signed