Support for scaling?

[chrisdebruin]

Are there any plans for adding support to scale containers (on the same host) up and down? Something you can do with docker-compose for example docker-compose up -d --scale service=2

As far as I can see traefik already supports this. Not sure if this is the direction you want to go.

Thanks, keep up the good work

[dhh]

Not needed when using puma. You can set WEB_CONCURRENCY to the number of workers you want to run on the given host as an ENV variable. Also, this isn't using compose behind the scenes, just vanilla Docker 👍

[chrisdebruin]

Ok. I thought the general idea with docker was to run a single process and don't do forks when running container. Instead you would run container with WEB_CONCURRENCY=1. If you need more workers you just spinup more containers

[dhh]

Needlessly complicated with no payback. Totally fine to run multiple sub processes of the same overall process.

[lado936]

Hello @dhh, what about use case when i am not using rails related framework? we started deploying with kamal, for different type applications and need to have possibility to scale containers in one vm. Is there any possible workaround we can use or should we drop kamal when version 2 will arrive?

[dhh]

Any framework that's unable to take advantage of multiple processors would not be one I'd spend any time on. I don't think that's a common issue these days, though. But do whatever you need to do to fit the environment you're in. But Kamal is not and will not be built on docker compose.