I’ve been running GitHub Actions workflows for a while, and when GitHub announced the new ubuntu-slim runners as a cheaper alternative to ubuntu-latest, I wanted to migrate—but figuring out which workflows are safe to switch turned out to be surprisingly tedious.

You need to check for Docker usage, services, containers, step failures due to missing packages, and whether jobs rely on tools not available in the slim image.

So I built gh-slimify, a GitHub CLI extension that automates all of this. It scans your repository, detects which jobs can be migrated, flags incompatible patterns, identifies missing commands, and can update only the safe workflows with a single command.

gh extension install fchimpan/gh-slimify gh slimfy # Analyze workflows gh slimfy fix # Update only jobs that are safe to migrate

It’s open source (MIT). As a bonus: the README also includes an AI agent prompt that reproduces the same workflow-migration analysis—useful if you want to integrate the logic into an LLM agent or experiment with automated refactoring.

I’d love feedback—especially on edge cases, false positives/negatives, or patterns it should detect better.