Pulumi: Modify Existing Files

Always modify, never create

Infrastructure changes belong in the existing entrypoint for the stack (typically __main__.py). Do not create additional Pulumi files unless the stack already follows a multi-file pattern that makes a new file the right fit.

Preserve existing functionality

When editing a Pulumi stack entrypoint, the following must never be silently removed:

• assumeRole / cross-account role configuration — removing this breaks production deployments that depend on cross-account access.
• Existing resource exports (pulumi.export(...)).
• Stack references to other stacks.

Before finalizing changes, scan the diff to confirm nothing was deleted unintentionally.

Validate changes before declaring done

After modifying any Pulumi code, run a preview to confirm the plan is correct:

pulumi preview --stack <stack-name>

Review the output carefully:

• Unexpected resource replacements or deletions are bugs, not acceptable side effects.
• "0 changes" is only correct if you genuinely expected no changes.