Add --skip-install flag to databricks apps init (#5396)

Previously `apps init` always ran the project's dependency installer
(npm ci, uv sync, or pip install + venv) and there was no way to opt
out. Add a --skip-install flag that:

- skips the background npm install kicked off during prompts
- skips the per-project initializer (npm/uv/pip install plus the Node.js
`npx appkit setup` step)
- still surfaces the project's NextSteps() hint on success

Rejects --skip-install + --run dev / --run dev-remote up front since
both modes require installed dependencies. --deploy is still allowed
because it runs server-side and does not need a local node_modules.

## Changes
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## Why
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might be missing.
For example, were there any decisions behind the change that are not
reflected in the code itself? -->

## Tests
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<!-- If your PR needs to be included in the release notes for next
release,
add a separate entry in NEXT_CHANGELOG.md as part of your PR. -->

---------

Co-authored-by: MarioCadenas <MarioCadenas@users.noreply.github.com>
Co-authored-by: Fabian Jakobs <fabian.jakobs@databricks.com>

Author: MarioCadenas

cmd/apps/init.go

@@ -78,6 +78,7 @@ func newInitCmd() *cobra.Command {
 		run          string
 		setValues    []string
 		autoApprove  bool
+		skipInstall  bool
 	)
 
 	cmd := &cobra.Command{
@@ -162,6 +163,7 @@ Environment variables:
 				pluginsChanged: cmd.Flags().Changed("features") || cmd.Flags().Changed("plugins"),
 				setValues:      setValues,
 				autoApprove:    autoApprove,
+				skipInstall:    skipInstall,
 			})
 		},
 	}
@@ -181,6 +183,7 @@ Environment variables:
 	cmd.Flags().BoolVar(&deploy, "deploy", false, "Deploy the app after creation")
 	cmd.Flags().StringVar(&run, "run", "", "Run the app after creation (none, dev, dev-remote)")
 	cmd.Flags().BoolVar(&autoApprove, "auto-approve", false, "Skip confirmation prompts for optional resources. Optional resources are only configured when their values are provided via --set.")
+	cmd.Flags().BoolVar(&skipInstall, "skip-install", false, "Skip installing project dependencies (e.g. npm install / uv sync). Cannot be combined with --run.")
 
 	return cmd
 }
@@ -202,6 +205,7 @@ type createOptions struct {
 	pluginsChanged bool     // true if --plugins flag was explicitly set
 	setValues      []string // --set plugin.resourceKey.field=value pairs
 	autoApprove    bool
+	skipInstall    bool
 }
 
 // parseSetValues parses --set key=value pairs into the resourceValues map.
@@ -796,6 +800,13 @@ func awaitBackgroundNpmInstall(ctx context.Context, ch <-chan error) error {
 }
 
 func runCreate(ctx context.Context, opts createOptions) error {
+	// --skip-install leaves the project without installed dependencies, so
+	// downstream `--run dev` / `--run dev-remote` would immediately fail.
+	// Reject the combination up front rather than after the scaffold runs.
+	if opts.skipInstall && opts.run != "" && opts.run != "none" {
+		return errors.New("--skip-install cannot be combined with --run (dev/dev-remote require dependencies to be installed)")
+	}
+
 	var selectedPlugins []string
 	var resourceValues map[string]string
 	var shouldDeploy bool
@@ -983,8 +994,12 @@ func runCreate(ctx context.Context, opts createOptions) error {
 
 	// Start npm install in the background so it runs while the user answers prompts.
 	// This is a Node.js-only optimisation — non-Node templates skip this.
+	// Honour --skip-install by not kicking off the background install at all.
 	srcProjectDir := findProjectSrcDir(templateDir)
-	npmInstallCh := startBackgroundNpmInstall(ctx, srcProjectDir, destDir, opts.name)
+	var npmInstallCh <-chan error
+	if !opts.skipInstall {
+		npmInstallCh = startBackgroundNpmInstall(ctx, srcProjectDir, destDir, opts.name)
+	}
 
 	// Step 3: Load manifest from template (optional — templates without it skip plugin/resource logic)
 	var m *manifest.Manifest
@@ -1223,17 +1238,23 @@ func runCreate(ctx context.Context, opts createOptions) error {
 	// Initialize project based on type (Node.js, Python, etc.).
 	// For Node.js, if the background install succeeded node_modules exists
 	// and the initializer skips the redundant install step.
+	// With --skip-install we bypass Initialize entirely and instead prepend
+	// the install command to NextSteps so the user knows to install first.
 	var nextStepsCmd string
 	projectInitializer := initializer.GetProjectInitializer(absOutputDir)
 	if projectInitializer != nil {
-		result := projectInitializer.Initialize(ctx, absOutputDir)
-		if !result.Success {
-			if result.Error != nil {
-				return fmt.Errorf("%s: %w", result.Message, result.Error)
+		if opts.skipInstall {
+			nextStepsCmd = prependInstall(projectInitializer.InstallCommand(), projectInitializer.NextSteps())
+		} else {
+			result := projectInitializer.Initialize(ctx, absOutputDir)
+			if !result.Success {
+				if result.Error != nil {
+					return fmt.Errorf("%s: %w", result.Message, result.Error)
+				}
+				return errors.New(result.Message)
 			}
-			return errors.New(result.Message)
+			nextStepsCmd = projectInitializer.NextSteps()
 		}
-		nextStepsCmd = projectInitializer.NextSteps()
 	}
 
 	// Validate dev-remote is only supported for appkit projects
@@ -1355,6 +1376,18 @@ func runPostCreateDev(ctx context.Context, mode prompt.RunMode, projectInit init
 	}
 }
 
+// prependInstall composes the install command and the project's NextSteps
+// suggestion into a single shell snippet, dropping either side if empty.
+func prependInstall(installCmd, nextStepsCmd string) string {
+	if installCmd == "" {
+		return nextStepsCmd
+	}
+	if nextStepsCmd == "" {
+		return installCmd
+	}
+	return installCmd + " && " + nextStepsCmd
+}
+
 // appendUnique appends values to a slice, skipping duplicates.
 func appendUnique(base []string, values ...string) []string {
 	seen := make(map[string]bool, len(base))

cmd/apps/init_test.go

@@ -1148,3 +1148,45 @@ func TestRunCreate_NameDotAndOutputDirAreMutuallyExclusive(t *testing.T) {
 	require.Error(t, err)
 	assert.ErrorIs(t, err, prompt.ErrNameDotWithOutputDir)
 }
+
+func TestRunCreate_SkipInstallRejectsRun(t *testing.T) {
+	ctx := cmdio.MockDiscard(t.Context())
+	for _, runMode := range []string{"dev", "dev-remote"} {
+		t.Run(runMode, func(t *testing.T) {
+			err := runCreate(ctx, createOptions{
+				name:         "my-app",
+				nameProvided: true,
+				skipInstall:  true,
+				run:          runMode,
+			})
+			require.Error(t, err)
+			assert.Contains(t, err.Error(), "--skip-install cannot be combined with --run")
+		})
+	}
+}
+
+func TestInitCmd_SkipInstallFlagRegistered(t *testing.T) {
+	cmd := newInitCmd()
+	flag := cmd.Flags().Lookup("skip-install")
+	require.NotNil(t, flag)
+	assert.Equal(t, "false", flag.DefValue)
+}
+
+func TestPrependInstall(t *testing.T) {
+	tests := []struct {
+		name      string
+		install   string
+		nextSteps string
+		want      string
+	}{
+		{"both set", "npm ci", "npm run dev", "npm ci && npm run dev"},
+		{"empty install", "", "npm run dev", "npm run dev"},
+		{"empty next steps", "npm ci", "", "npm ci"},
+		{"both empty", "", "", ""},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.want, prependInstall(tt.install, tt.nextSteps))
+		})
+	}
+}

libs/apps/initializer/initializer.go

@@ -24,6 +24,12 @@ type Initializer interface {
 	// NextSteps returns the next steps message for this project type.
 	NextSteps() string
 
+	// InstallCommand returns the shell command that installs the project's
+	// dependencies (and any prerequisites like a virtualenv). It is shown
+	// to the user when init was run with --skip-install so the user knows
+	// what to run before NextSteps.
+	InstallCommand() string
+
 	// RunDev starts the local development server.
 	RunDev(ctx context.Context, workDir string) error
 

libs/apps/initializer/initializer_test.go

@@ -87,6 +87,22 @@ func TestNextSteps(t *testing.T) {
 	assert.Contains(t, pythonPip.NextSteps(), ".venv")
 }
 
+func TestInstallCommand(t *testing.T) {
+	nodejs := &InitializerNodeJs{}
+	assert.Equal(t, "npm ci", nodejs.InstallCommand())
+
+	pythonUv := &InitializerPythonUv{}
+	assert.Equal(t, "uv sync", pythonUv.InstallCommand())
+
+	// pip's install command creates the venv and installs via the full pip
+	// path so it composes with NextSteps (which activates the venv).
+	pythonPip := &InitializerPythonPip{}
+	got := pythonPip.InstallCommand()
+	assert.Contains(t, got, "venv .venv")
+	assert.Contains(t, got, "pip install -r requirements.txt")
+	assert.NotContains(t, got, "activate", "should not activate; NextSteps handles activation")
+}
+
 func TestSupportsDevRemote(t *testing.T) {
 	// Node.js without appkit
 	nodejs := &InitializerNodeJs{workDir: ""}

libs/apps/initializer/nodejs.go

@@ -52,6 +52,12 @@ func (i *InitializerNodeJs) NextSteps() string {
 	return "npm run dev"
 }
 
+func (i *InitializerNodeJs) InstallCommand() string {
+	// Mirrors runNpmInstall — `npm ci` reproduces the lockfile and is what
+	// the background install in cmd/apps would have run.
+	return "npm ci"
+}
+
 func (i *InitializerNodeJs) RunDev(ctx context.Context, workDir string) error {
 	cmdio.LogString(ctx, "Starting development server (npm run dev)...")
 	cmd := exec.CommandContext(ctx, "npm", "run", "dev")

libs/apps/initializer/python_pip.go

@@ -51,6 +51,16 @@ func (i *InitializerPythonPip) NextSteps() string {
 	return "source .venv/bin/activate && python app.py"
 }
 
+func (i *InitializerPythonPip) InstallCommand() string {
+	// Create the venv and install via the full pip path so the suggestion
+	// composes with NextSteps (which activates the venv) without
+	// activating twice.
+	if runtime.GOOS == "windows" {
+		return "python -m venv .venv && .venv\\Scripts\\pip install -r requirements.txt"
+	}
+	return "python3 -m venv .venv && .venv/bin/pip install -r requirements.txt"
+}
+
 func (i *InitializerPythonPip) RunDev(ctx context.Context, workDir string) error {
 	cmd := detectPythonCommand(workDir)
 	cmdStr := strings.Join(cmd, " ")

libs/apps/initializer/python_uv.go

@@ -42,6 +42,10 @@ func (i *InitializerPythonUv) NextSteps() string {
 	return "uv run python app.py"
 }
 
+func (i *InitializerPythonUv) InstallCommand() string {
+	return "uv sync"
+}
+
 func (i *InitializerPythonUv) RunDev(ctx context.Context, workDir string) error {
 	appCmd := detectPythonCommand(workDir)
 	cmdStr := "uv run " + strings.Join(appCmd, " ")