Support checkout skipping in agent

agent/agent_configuration.go

@@ -24,6 +24,7 @@ type AgentConfiguration struct {
 	GitCleanFlags               string
 	GitFetchFlags               string
 	GitSubmodules               bool
+	SkipCheckout                bool
 	AllowedRepositories         []*regexp.Regexp
 	AllowedPlugins              []*regexp.Regexp
 	AllowedEnvironmentVariables []*regexp.Regexp

agent/job_runner.go

@@ -577,6 +577,12 @@ BUILDKITE_AGENT_JWKS_KEY_ID`
 	setEnv("BUILDKITE_PLUGINS_PATH", r.conf.AgentConfiguration.PluginsPath)
 	setEnv("BUILDKITE_SSH_KEYSCAN", fmt.Sprint(r.conf.AgentConfiguration.SSHKeyscan))
 	setEnv("BUILDKITE_GIT_SUBMODULES", fmt.Sprint(r.conf.AgentConfiguration.GitSubmodules))
+	// Allow BUILDKITE_SKIP_CHECKOUT to be enabled either by agent config
+	// or by pipeline/step env
+	// This is here now to make it ready for if/when we add skip_checkout to the core app
+	if r.conf.AgentConfiguration.SkipCheckout {
+		setEnv("BUILDKITE_SKIP_CHECKOUT", "true")
+	}
 	setEnv("BUILDKITE_COMMAND_EVAL", fmt.Sprint(r.conf.AgentConfiguration.CommandEval))
 	setEnv("BUILDKITE_PLUGINS_ENABLED", fmt.Sprint(r.conf.AgentConfiguration.PluginsEnabled))
 	// Allow BUILDKITE_PLUGINS_ALWAYS_CLONE_FRESH to be enabled either by config

clicommand/agent_start.go

@@ -150,6 +150,7 @@ type AgentStartConfig struct {
 	GitMirrorsLockTimeout int    `cli:"git-mirrors-lock-timeout"`
 	GitMirrorsSkipUpdate  bool   `cli:"git-mirrors-skip-update"`
 	NoGitSubmodules       bool   `cli:"no-git-submodules"`
+	SkipCheckout          bool   `cli:"skip-checkout"`
 
 	NoSSHKeyscan            bool     `cli:"no-ssh-keyscan"`
 	NoCommandEval           bool     `cli:"no-command-eval"`
@@ -624,6 +625,11 @@ var AgentStartCommand = cli.Command{
 			Usage:  "Don't automatically checkout git submodules",
 			EnvVar: "BUILDKITE_NO_GIT_SUBMODULES,BUILDKITE_DISABLE_GIT_SUBMODULES",
 		},
+		cli.BoolFlag{
+			Name:   "skip-checkout",
+			Usage:  "Skip the git checkout phase entirely",
+			EnvVar: "BUILDKITE_SKIP_CHECKOUT",
+		},
 		cli.BoolFlag{
 			Name:   "no-feature-reporting",
 			Usage:  "Disables sending a list of enabled features back to the Buildkite mothership. We use this information to measure feature usage, but if you're not comfortable sharing that information then that's totally okay :)",
@@ -1040,6 +1046,7 @@ var AgentStartCommand = cli.Command{
 			GitCleanFlags:                cfg.GitCleanFlags,
 			GitFetchFlags:                cfg.GitFetchFlags,
 			GitSubmodules:                !cfg.NoGitSubmodules,
+			SkipCheckout:                 cfg.SkipCheckout,
 			SSHKeyscan:                   !cfg.NoSSHKeyscan,
 			CommandEval:                  !cfg.NoCommandEval,
 			PluginsEnabled:               !cfg.NoPlugins,

clicommand/bootstrap.go

@@ -68,6 +68,7 @@ type BootstrapConfig struct {
 	AutomaticArtifactUploadPaths string   `cli:"artifact-upload-paths"`
 	ArtifactUploadDestination    string   `cli:"artifact-upload-destination"`
 	CleanCheckout                bool     `cli:"clean-checkout"`
+	SkipCheckout                 bool     `cli:"skip-checkout"`
 	GitCheckoutFlags             string   `cli:"git-checkout-flags"`
 	GitCloneFlags                string   `cli:"git-clone-flags"`
 	GitFetchFlags                string   `cli:"git-fetch-flags"`
@@ -227,6 +228,11 @@ var BootstrapCommand = cli.Command{
 			Usage:  "Whether or not the bootstrap should remove the existing repository before running the command",
 			EnvVar: "BUILDKITE_CLEAN_CHECKOUT",
 		},
+		cli.BoolFlag{
+			Name:   "skip-checkout",
+			Usage:  "Skip the git checkout phase entirely",
+			EnvVar: "BUILDKITE_SKIP_CHECKOUT",
+		},
 		cli.StringFlag{
 			Name:   "git-checkout-flags",
 			Value:  "-f",
@@ -468,6 +474,7 @@ var BootstrapCommand = cli.Command{
 			CancelSignal:                 cancelSig,
 			SignalGracePeriod:            signalGracePeriod,
 			CleanCheckout:                cfg.CleanCheckout,
+			SkipCheckout:                 cfg.SkipCheckout,
 			Command:                      cfg.Command,
 			CommandEval:                  cfg.CommandEval,
 			Commit:                       cfg.Commit,

internal/job/checkout.go

@@ -217,6 +217,11 @@ func (e *Executor) CheckoutPhase(ctx context.Context) error {
 
 // checkout runs checkout hook or default checkout logic
 func (e *Executor) checkout(ctx context.Context) error {
+	if e.SkipCheckout {
+		e.shell.Commentf("Skipping checkout, BUILDKITE_SKIP_CHECKOUT is set")
+		return nil
+	}
+
 	// There can only be one checkout hook, either plugin or global, in that order
 	switch {
 	case e.hasPluginHook("checkout"):

internal/job/checkout_test.go

@@ -147,6 +147,26 @@ func TestDefaultCheckoutPhase(t *testing.T) {
 	}
 }
 
+func TestSkipCheckout(t *testing.T) {
+	t.Parallel()
+
+	ctx := context.Background()
+
+	sh, err := shell.New()
+	require.NoError(t, err)
+
+	executor := &Executor{
+		shell: sh,
+		ExecutorConfig: ExecutorConfig{
+			Repository:   "https://github.com/buildkite/agent.git",
+			SkipCheckout: true,
+		},
+	}
+
+	err = executor.checkout(ctx)
+	require.NoError(t, err)
+}
+
 func TestDefaultCheckoutPhase_DelayedRefCreation(t *testing.T) {
 	if race.IsRaceTest {
 		t.Skip("this test simulates the agent recovering from a race condition, and needs to create one to test it.")

internal/job/config.go

@@ -75,6 +75,9 @@ type ExecutorConfig struct {
 	// Should the executor remove an existing checkout before running the job
 	CleanCheckout bool `env:"BUILDKITE_CLEAN_CHECKOUT"`
 
+	// Skip the checkout phase entirely
+	SkipCheckout bool `env:"BUILDKITE_SKIP_CHECKOUT"`
+
 	// Flags to pass to "git checkout" command
 	GitCheckoutFlags string `env:"BUILDKITE_GIT_CHECKOUT_FLAGS"`
 

internal/job/integration/checkout_integration_test.go

@@ -849,6 +849,27 @@ func TestForcingACleanCheckout(t *testing.T) {
 	}
 }
 
+func TestSkippingCheckout(t *testing.T) {
+	t.Parallel()
+
+	tester, err := NewExecutorTester(mainCtx)
+	if err != nil {
+		t.Fatalf("NewExecutorTester() error = %v", err)
+	}
+	defer tester.Close()
+
+	tester.RunAndCheck(t, "BUILDKITE_SKIP_CHECKOUT=true")
+
+	if !strings.Contains(tester.Output, "Skipping checkout") {
+		t.Fatal(`tester.Output does not contain "Skipping checkout"`)
+	}
+
+	// Verify no git commands were run (no clone, fetch, checkout)
+	if strings.Contains(tester.Output, "git clone") {
+		t.Fatal(`tester.Output should not contain "git clone" when checkout is skipped`)
+	}
+}
+
 func TestCheckoutOnAnExistingRepositoryWithoutAGitFolder(t *testing.T) {
 	t.Parallel()