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Interactive File Generation for Terraform, Helmfile, and Packer

· 2 min read
Erik Osterman
Erik Osterman
Founder @ Cloud Posse

File generation now features interactive component and stack selection, plus cross-provisioner support for helmfile and packer. Run atmos terraform generate files without arguments and get an intuitive selector.

What Changed​

Building on the declarative file generation feature, this release adds several improvements:

  • Interactive prompts for component and stack selection when arguments are missing
  • Cross-provisioner support for helmfile and packer (not just terraform)
  • Idempotent generation that only writes files when content changes
  • Deterministic output with sorted map keys for reproducible generation
  • JIT component creation with auto-generation running BEFORE path validation
$ atmos terraform generate files
? Choose a component
  > vpc
    eks-cluster
    rds-aurora
? Choose a stack
  > ue2-dev
    ue2-prod

Why This Matters​

Discoverability​

When working with unfamiliar infrastructure, you may not know which components have file generation configured. Interactive prompts let you explore what's available without digging through YAML files.

Cross-Provisioner Consistency​

Teams using helmfile or packer alongside terraform can now use the same file generation patterns across all provisioners:

# atmos.yaml
components:
  terraform:
    auto_generate_files: true
  helmfile:
    auto_generate_files: true
  packer:
    auto_generate_files: true

Idempotent Operations​

File generation now compares existing content before writing. This means:

  • No unnecessary file modifications
  • Cleaner git diffs
  • Faster execution when files haven't changed

How It Works​

Interactive Selection​

When you omit the component or stack argument in an interactive terminal, Atmos prompts for selection:

$ atmos terraform generate files
? Choose a component
  > vpc
i Selected component `vpc`
? Choose a stack
  > ue2-dev
i Selected stack `ue2-dev`

Generating files for component `vpc` in stack `ue2-dev`...

JIT Component Creation​

With auto_generate_files: true, files are generated BEFORE path validation during component execution. This enables just-in-time component creation where the generated files can create the component directory itself.

Summary Output​

After generation, you see exactly what changed:

✓ Generated file: locals.tf
✓ Generated file: context.json
i Summary: 2 files generated (2 created, 0 updated, 0 unchanged)

Disabling Interactive Prompts​

For scripts and automation, disable prompts the same way as other interactive commands:

# Via flag
atmos terraform generate files vpc -s ue2-dev --interactive=false

# Via environment variable
export ATMOS_INTERACTIVE=false

Get Involved​