Add module/stack targeting and changeset support for CI/CD workflows

[neelaruban]

New CLI options for granular targeting:

• --module: Select modules by name or glob pattern (e.g., 'network-*')
• --stack: Select specific CFNgin stacks within targeted modules

CloudFormation changeset support for CI/CD pipelines:

• runway plan --create-changeset: Retain changesets for later execution
• runway plan --output json: Machine-readable changeset output
• runway deploy --execute-changesets : Execute pre-created changesets

New 'runway variables' command:

• Show resolved variables for deployments and modules
• Supports YAML, JSON, and table output formats
• Resolves all lookups (${var}, ${env}, ${ssm}, etc.)

Context updates:

• Added stack_names, create_changeset, changeset_results to contexts
• Propagate targeting options from CLI through to CFNgin

Includes integration tests for all new options.

Summary

This PR adds granular targeting capabilities for Runway CLI commands and introduces CloudFormation changeset support for CI/CD workflows. Users can now target specific modules by name/pattern and
specific CFNgin stacks, enabling more precise deployments. Additionally, a new runway variables command helps debug variable resolution issues.

Why This Is Needed

1. Granular Deployments: In large mono-repos with many modules, users often need to deploy only specific modules or stacks without modifying config files or using tags. The --module and --stack
   options provide this flexibility.
2. CI/CD Pipeline Support: CloudFormation changesets created during runway plan were being deleted immediately. For CI/CD pipelines that require a "plan → approve → apply" workflow, changesets need
   to be retained and executed in separate stages.
3. Debugging Variable Resolution: When lookups (${var}, ${ssm}, ${env}) fail or resolve unexpectedly, there was no easy way to see the final resolved values. The variables command addresses this.

What Changed

• --module option for deploy, destroy, init, and plan commands
  • Select modules by exact name or glob pattern (e.g., --module "network-*")
  • Supports multiple values (e.g., --module vpc --module rds)
  • --stack option for targeting specific CFNgin stacks within modules
  • --create-changeset flag for runway plan to retain changesets
  • --output json|text option for machine-readable changeset output
  • --execute-changesets option for runway deploy to execute pre-created changesets
  • New runway variables command with YAML, JSON, and table output formats
  • New modules:
    • runway/_cli/changeset_executor.py - Executes retained changesets
    • runway/_cli/changeset_output.py - Formats changeset output for CI/CD
    • runway/_cli/commands/_variables.py - Variables inspection command
  • Integration tests for all new CLI options

Added

Changed

• RunwayContext and CfnginContext now track:
  • stack_names - List of targeted stack names
  • create_changeset - Whether to retain changesets
  • changeset_results - Mapping of stack FQN to changeset ID
  • select_deployments() now accepts module_names parameter for filtering
  • Provider.get_stack_changes() accepts retain_changeset parameter
  • CFNgin.plan() returns changeset mapping and propagates to RunwayContext
  • Updated CLI help text to document new --module and --tag options

Fixed

Removed

Screenshots

Checklist

• Have you followed the guidelines in our Contribution Requirements?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Does your submission pass tests?
• Have you linted your code locally prior to submission?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your core changes, as applicable?
• Have you successfully ran tests with your changes locally?
• Have you updated documentation, as applicable?

[neelaruban]

@mbordash2 @jon-the-dev Could someone look into this please :)

[mbordash2]

@ITProKyle

[codecov-commenter]

Codecov Report

❌ Patch coverage is 64.46991% with 124 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.84%. Comparing base (9642067) to head (3bc13a7).

Files with missing lines	Patch %	Lines
runway/_cli/changeset_executor.py	19.14%	76 Missing ⚠️
runway/_cli/commands/_variables.py	79.66%	24 Missing ⚠️
runway/_cli/changeset_output.py	25.00%	18 Missing ⚠️
runway/cfngin/actions/diff.py	0.00%	2 Missing ⚠️
runway/cfngin/providers/aws/default.py	80.00%	2 Missing ⚠️
runway/_cli/commands/_deploy.py	93.75%	1 Missing ⚠️
runway/cfngin/utils.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2930      +/-   ##
==========================================
- Coverage   90.42%   89.84%   -0.59%     
==========================================
  Files         231      234       +3     
  Lines       14939    15267     +328     
==========================================
+ Hits        13509    13716     +207     
- Misses       1430     1551     +121     

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[mbordash2]

@neelaruban can you please take a look at the linting and test coverage notices? Thanks!

[neelaruban]

@neelaruban can you please take a look at the linting and test coverage notices? Thanks!

@mbordash2 i have done those changes now it looks good :)

[neelaruban]

@mbordash2 I have fixed the Linting issues , now it looks good