feat: Add interactive file generation for terraform, helmfile, and packer

cmd/terraform/generate/files.go

@@ -7,6 +7,7 @@ import (
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 
+	"github.com/cloudposse/atmos/cmd/terraform/shared"
 	errUtils "github.com/cloudposse/atmos/errors"
 	e "github.com/cloudposse/atmos/internal/exec"
 	cfg "github.com/cloudposse/atmos/pkg/config"
@@ -50,15 +51,41 @@ The generate section in stack configuration supports:
 		dryRun := v.GetBool("dry-run")
 		clean := v.GetBool("clean")
 
-		// Validate: component requires stack, --all excludes component.
+		// Validate: --all excludes component argument.
 		if len(args) > 0 && all {
 			return fmt.Errorf("%w: cannot specify both component and --all", errUtils.ErrInvalidFlag)
 		}
-		if len(args) > 0 && stack == "" {
-			return fmt.Errorf("%w: --stack is required when specifying a component", errUtils.ErrInvalidFlag)
+
+		// Get component from args or prompt for it (when not using --all).
+		var component string
+		if len(args) > 0 {
+			component = args[0]
+		} else if !all {
+			// Prompt for component if missing.
+			prompted, err := shared.PromptForComponent(cmd, "")
+			if err = shared.HandlePromptError(err, "component"); err != nil {
+				return err
+			}
+			component = prompted
 		}
-		if len(args) == 0 && !all {
-			return fmt.Errorf("%w: either specify a component or use --all", errUtils.ErrInvalidFlag)
+
+		// Validate component after prompting (required when not using --all).
+		if !all && component == "" {
+			return errUtils.ErrMissingComponent
+		}
+
+		// Prompt for stack if missing (required when component is specified).
+		if component != "" && stack == "" {
+			prompted, err := shared.PromptForStack(cmd, component)
+			if err = shared.HandlePromptError(err, "stack"); err != nil {
+				return err
+			}
+			stack = prompted
+		}
+
+		// Validate stack after prompting (required when component is specified).
+		if component != "" && stack == "" {
+			return errUtils.ErrMissingStack
 		}
 
 		// Parse CSV values with whitespace trimming.
@@ -102,7 +129,6 @@ The generate section in stack configuration supports:
 			return service.ExecuteForAll(&atmosConfig, stacks, components, dryRun, clean)
 		}
 
-		component := args[0]
 		return service.ExecuteForComponent(&atmosConfig, component, stack, dryRun, clean)
 	},
 }
@@ -129,6 +155,9 @@ func init() {
 		panic(err)
 	}
 
+	// Register shell completion for component.
+	filesCmd.ValidArgsFunction = shared.ComponentsArgCompletion
+
 	// Register with parent GenerateCmd.
 	GenerateCmd.AddCommand(filesCmd)
 }

cmd/terraform/generate/generate_test.go

@@ -444,3 +444,69 @@ func TestVarfileValidation(t *testing.T) {
 		assert.ErrorIs(t, err, errUtils.ErrMissingComponent)
 	})
 }
+
+// TestFilesValidation tests validation errors in the files command.
+func TestFilesValidation(t *testing.T) {
+	t.Run("component with all flag returns error", func(t *testing.T) {
+		// Get the global viper instance and set up clean state.
+		v := viper.GetViper()
+		// Reset flags that might interfere.
+		v.Set("all", true)
+		v.Set("stack", "test-stack") // Provide stack to avoid that error.
+		defer func() {
+			// Clean up.
+			v.Set("all", false)
+			v.Set("stack", "")
+		}()
+
+		// Create a test command to execute RunE directly.
+		cmd := &cobra.Command{Use: "files"}
+		filesParser.RegisterFlags(cmd)
+
+		// Execute RunE with component argument and --all flag set in viper.
+		err := filesCmd.RunE(cmd, []string{"my-component"})
+		assert.ErrorIs(t, err, errUtils.ErrInvalidFlag)
+	})
+
+	t.Run("missing component without all flag returns error", func(t *testing.T) {
+		// Get the global viper instance and set up clean state.
+		v := viper.GetViper()
+		v.Set("all", false)
+		v.Set("stack", "")
+		defer func() {
+			// Clean up.
+			v.Set("all", false)
+			v.Set("stack", "")
+		}()
+
+		// Create a test command to execute RunE directly.
+		cmd := &cobra.Command{Use: "files"}
+		filesParser.RegisterFlags(cmd)
+
+		// Execute RunE with no component argument and no --all flag.
+		// In non-TTY environment, the prompt returns ErrInteractiveModeNotAvailable.
+		err := filesCmd.RunE(cmd, []string{})
+		assert.ErrorIs(t, err, errUtils.ErrMissingComponent)
+	})
+
+	t.Run("component without stack returns error", func(t *testing.T) {
+		// Get the global viper instance and set up clean state.
+		v := viper.GetViper()
+		v.Set("all", false)
+		v.Set("stack", "")
+		defer func() {
+			// Clean up.
+			v.Set("all", false)
+			v.Set("stack", "")
+		}()
+
+		// Create a test command to execute RunE directly.
+		cmd := &cobra.Command{Use: "files"}
+		filesParser.RegisterFlags(cmd)
+
+		// Execute RunE with component argument but no stack.
+		// In non-TTY environment, the prompt returns ErrInteractiveModeNotAvailable.
+		err := filesCmd.RunE(cmd, []string{"my-component"})
+		assert.ErrorIs(t, err, errUtils.ErrMissingStack)
+	})
+}

examples/generate-files/.gitignore

@@ -0,0 +1,8 @@
+# Components folder (created during example usage)
+components/
+
+# Terraform
+.terraform/
+*.tfstate*
+*.tfvars.json
+backend.tf.json

examples/generate-files/README.md

@@ -0,0 +1,182 @@
+# Generate Files
+
+This example demonstrates how to use `atmos terraform generate files` to generate an entire Terraform component from stack configuration.
+
+## Overview
+
+The `generate` section in component configuration defines files that Atmos will create. This example generates a complete Terraform component including:
+
+- `variables.tf` - Variable definitions
+- `outputs.tf` - Output definitions
+- `versions.tf` - Terraform version constraints
+- `locals.tf` - Local values
+- `terraform.tfvars` - Variable values
+- `config.json` - Environment-specific configuration
+- `README.md` - Component documentation
+
+## Content Types
+
+| Content Type | Behavior |
+|--------------|----------|
+| String (multiline) | Written as-is, supports Go templates |
+| Map with `.json` extension | Serialized as pretty-printed JSON |
+| Map with `.yaml`/`.yml` extension | Serialized as YAML |
+| Map with `.tf`/`.hcl` extension | Serialized as HCL blocks |
+| Map with `.tfvars` extension | Serialized as HCL attributes (no blocks) |
+
+### HCL Generation
+
+When using map syntax for `.tf` files, Atmos automatically handles:
+
+- **Labeled blocks** (`variable`, `output`, `resource`, `data`, `module`, `provider`):
+  ```yaml
+  variable:
+    app_name:
+      type: string
+      description: "Application name"
+  ```
+  Generates: `variable "app_name" { type = "string" ... }`
+
+- **Unlabeled blocks** (`terraform`, `locals`):
+  ```yaml
+  terraform:
+    required_version: ">= 1.0.0"
+  ```
+  Generates: `terraform { required_version = ">= 1.0.0" }`
+
+**Note:** For blocks that need HCL expressions (like `value = var.app_name`), use string templates instead of map syntax.
+
+## Template Variables
+
+Available in templates via `{{ .variable }}`:
+
+| Variable | Description |
+|----------|-------------|
+| `atmos_component` | Component name |
+| `atmos_stack` | Stack name |
+| `vars` | Component variables (map) |
+| `vars.stage` | Stage from component vars |
+
+## Auto-Generation
+
+Enable automatic file generation on any terraform command:
+
+```yaml
+# atmos.yaml
+components:
+  terraform:
+    auto_generate_files: true
+```
+
+With this enabled, files are regenerated before `init`, `plan`, `apply`, etc.
+
+## Usage
+
+### Generate the component
+
+```bash
+cd examples/generate-files
+mkdir -p components/terraform/demo
+atmos terraform generate files demo -s dev
+```
+
+### Preview without writing (dry-run)
+
+```bash
+atmos terraform generate files demo -s dev --dry-run
+```
+
+### Delete generated files (clean)
+
+```bash
+atmos terraform generate files demo -s dev --clean
+```
+
+## Generated Files
+
+After running `atmos terraform generate files demo -s dev`:
+
+**versions.tf** (HCL map syntax):
+```hcl
+terraform {
+  required_version = ">= 1.0.0"
+}
+```
+
+**locals.tf** (HCL map syntax with templates):
+```hcl
+locals {
+  app_name    = "myapp-dev"
+  environment = "dev"
+}
+```
+
+**variables.tf** (string template):
+```hcl
+variable "app_name" {
+  type        = string
+  description = "Application name"
+}
+```
+
+**terraform.tfvars** (flat HCL attributes):
+```hcl
+app_name = "myapp-dev"
+version  = "1.0.0-dev"
+```
+
+**config.json** (JSON from map):
+```json
+{
+  "app": "myapp-dev",
+  "stage": "dev",
+  "version": "1.0.0-dev"
+}
+```
+
+## Project Structure
+
+```text
+generate-files/
+├── atmos.yaml                    # Atmos configuration (auto_generate_files: true)
+├── components/                   # Generated (gitignored)
+│   └── terraform/
+│       └── demo/
+│           ├── variables.tf      # Generated
+│           ├── outputs.tf        # Generated
+│           ├── versions.tf       # Generated
+│           ├── locals.tf         # Generated
+│           ├── terraform.tfvars  # Generated
+│           ├── config.json       # Generated
+│           └── README.md         # Generated
+└── stacks/
+    ├── catalog/
+    │   └── demo.yaml             # Component with generate section
+    └── deploy/
+        ├── dev.yaml              # Dev environment
+        └── prod.yaml             # Prod environment
+```
+
+## Try It
+
+```bash
+cd examples/generate-files
+
+# Create component directory
+mkdir -p components/terraform/demo
+
+# Generate files for dev
+atmos terraform generate files demo -s dev
+
+# See what was generated
+ls components/terraform/demo/
+cat components/terraform/demo/versions.tf
+cat components/terraform/demo/locals.tf
+
+# Generate for prod (different values)
+atmos terraform generate files demo -s prod
+cat components/terraform/demo/config.json
+
+# Clean up
+atmos terraform generate files demo -s dev --clean
+```

examples/generate-files/atmos.yaml

@@ -0,0 +1,21 @@
+# Minimal Atmos configuration for file generation demo
+base_path: "./"
+
+components:
+  terraform:
+    base_path: "components/terraform"
+    apply_auto_approve: false
+    deploy_run_init: true
+    auto_generate_files: true
+
+stacks:
+  base_path: "stacks"
+  included_paths:
+    - "deploy/**/*"
+  excluded_paths:
+    - "**/_defaults.yaml"
+  name_template: "{{ .vars.stage }}"
+
+logs:
+  level: Info
+  file: "/dev/stderr"