# Blue-green releases

A step of the [Cloud application](https://gradus.kazet.blog/tree/cloud-application) tree on Gradus, in the Build & ship area: Config, lint, releases, IaC.

Page: https://gradus.kazet.blog/tree/cloud-application/step/blue-green-releases

Start each new version beside the live one with no traffic, test it on a private URL, switch traffic in one move and keep the old version ready to take it back.

Usually comes after: [Reversible migrations](https://gradus.kazet.blog/tree/cloud-application/step/reversible-migrations).

## Prompt for your AI assistant

```
Read the cloud provider decision record in docs/decisions and name this platform's own mechanism before changing anything: on Cloud Run a tagged revision deployed with no traffic, elsewhere the blue-green deployment the service offers. If the current service offers none, say so and stop for my decision. Change the deploy workflow so the new version starts without traffic on a URL of its own that search engines are told not to index, the smoke test runs against that URL, traffic moves only when it passes and the previous version stays ready to take it back. Run one real release through it and add what you learned to the decision record.
```

Every step of the tree: https://gradus.kazet.blog/tree/cloud-application/llms.txt