Pip: Shiel Yule has a question for your CI pipeline, and it is not the one your pipeline has been asking itself.
Mara: Today we’re covering a hackathon project that challenges a core assumption in modern software delivery — that a green build means you’re safe to ship.
Pip: Spoiler: it does not.
Mara: Let’s start with the project itself, and why rollback verification changes the picture entirely.
Undo – The Ghost of the Past Package
Pip: Here is the tension at the center of this project: most pipelines only look forward. They ask whether the new build works. Nobody asks whether the previous one still can.
Mara: The post puts it plainly — “Most pipelines only ask one question: Does the new build work? It’s a polite, forward-looking question. It’s optimistic. It’s hopelessly naive. In a real-world incident, the question that actually makes your stomach drop into your boots is far more brutal: Can we still run what we had before?”
Pip: That is the gap Undo is built to close. If you cannot prove the previous artifact still boots, your rollback plan is a theory, not a capability.
Mara: The project was built as a GitLab Life After Code hackathon entry. The loop it implements has four steps: Prove, Ask, Approve, and Promote. On every push to main, GitLab CI resurrects the previous package and hits a health endpoint — specifically a rollback verification check — before anything else moves forward.
Pip: And the Ask step is where it gets interesting. An event-driven GitLab Duo flow triggers automatically on pipeline success, reads the rollback proof, and opens a Work Item. No chat interface, just structured automation responding to a real signal.
Mara: The Approve step is deliberately minimal — one word from a human. The post is explicit about why: “even in an age of autonomous silicon agents, a human being should still be the one holding the smoking revolver when production goes sideways.”
Pip: A green pipeline on a laptop is, in the post’s words, “just a comforting delusion.” The Google Cloud infrastructure — service accounts, Cloud Build, Artifact Registry, and Cloud Run — is what gives the verification somewhere real to land.
Mara: The post closes with three principles worth keeping: event-driven flows beat chat demos, green is not the same as safe to promote, and a human still owns the final decision. The project repository, live demo, and Devpost submission are all linked for anyone who wants to inspect the pipeline directly.
Pip: Which means the corpse is available for prodding at your convenience.
Mara: The core idea here is durable — verification is not the same as validation, and rollback is not a fallback if nobody has tested it.
Pip: Next time, we find out what else the pipeline has been quietly assuming.
