Question: Is there a way to scale up or down during the rollout?

[korridor]

I have a docker compose setups and some services have multiple replicas.
I started using docker-rollout to have zero downtime, and that works great.
The only problem I have is that I don't now how to change the amount to replicas without a downtime. For example how to go from 3 replicas to 2 or from 3 to 4.
Is there a way to achieve that with docker-rollout?

[wowu]

If you want to change the number of running replicas you can just use docker compose up for this without downtime. The point of docker rollout is to replace containers by first starting new ones, and only then stopping the old ones, to always have at least 1 container running.

• If you want to increase the number of running replicas, edit the compose.yml file to increase the number of replicas and run docker compose up -d. Starting new containers does not cause downtime, especially if they have healthchecks defined, so Traefik can route traffic only when the app is ready to handle requests.
• If you want to decrease the number of running replicas, do the same. Stopping the containers will not cause downtime (except dropping currently processed requests, but neither docker rollout prevents this - at least until feat: true zero-downtime deployment with container draining #36 is merged)

If you don't have the replica count defined in the compose file, you can use docker compose up -d --scale web=3 syntax to change them.

[korridor]

@wowu Thanks for the information! :)