I'm working on a Ruby application, and I'm facing a challenge with my Docker setup. My Dockerfile starts with `FROM ruby:3.3`, which is the Ruby version I need. However, I also require some Postgres tools like `pg_dump` for handling migrations. I tried adding `RUN apt-get install postgresql-client` to install `pg_dump`, but it ends up being for Postgres 15, which doesn't work with my Postgres 17 container. I also attempted to copy `pg_dump` from the Postgres image using `COPY --from postgres:17.4 /usr/bin/pg_dump /usr/bin/`, but it failed due to missing shared libraries. So, I'm wondering how to effectively manage tools from two different images in my application. Must I build Ruby or Postgres myself, or is there a better approach?
2 Answers
It's generally better to keep your dependencies streamlined, so consider using a separate container for your migrations, especially during deployments. This way, you won’t clutter your Ruby container with extra tools that aren’t needed for its normal operations. If you need to install Postgres in your image, try debugging it in an interactive way using `docker exec -it sh`. That can make it easier to troubleshoot installation issues. Also, make sure to update your package list first; Postgres 17 might be available that way. If not, looking up how to install it manually could help you find a suitable source.
You can just install the specific version of the Postgres client you need with `apt install postgres-client-17`. You might need to add the right repository first, so check their documentation. Also, using the Ruby base image for a dev container isn’t ideal since its purpose is for application builds. Consider having separate Dockerfiles for dev and prod to avoid discrepancies between environments, like `Dockerfile.dev` and `Dockerfile.prod`. This way, you can test both setups and ensure nothing breaks when you deploy.
That's a good call! Having different Docker files helps keep things organized. Just make sure you thoroughly test both containers to avoid deploying any issues.
I agree, a dedicated migration container simplifies things overall. However, since your app's migrations rely on `pg_dump`, you'll still need that in your working container. It's a tough balance.