Fly.toml improvement thoughts

1

Just some thoughts as I’m working through deployments:

Lots of public Docker images want specific env vars set at runtime. It would be helpful to be able to ‘interpolate’ secrets or other env vars (like DATABASE_URL) within the variable expected by the image.

Being able to change env vars without a redeployment would be nice, similar to how changing a secret works now. I suppose this ties into the general desire for declarative deployment templates for other attributes.

It would be helpful to be able to specify a different Dockerfile for deployment, as well as a specific multistage target. Most of my apps do not use Dockerfile as the deployment target.

Finally, this is an interesting approach from AWS to support a subset of Docker Compose directly. This allows using the same configuration for local development. Not asking for this, just noting that it kills many birds with one stone :smiley:

2

That’s interesting. Can you give an example how you’d use it?

We’ll fix this over the next month or two.

You can do it now with the --dockerfile flag, or specify paths to everything like this:

flyctl deploy --dockerfile ./path/to/dockerfile --config ./path/to/config <path/to/context>

There’s also a hidden --build-target flag to set the target for multistage build files. You can use it right now and I’ll unhide it in the next release.

I also like docker compose for local dev. We’ve talked about it for deployment, but there’s a lot of compatibility we need to figure out. That link is interesting, thanks for sharing. Will think on that.

3

Thanks for the tips on the flags!

Interpolation would be used the same way you might do it with Docker Compose. Note: I edited this post because my previous post did not make sense. I will update my answer here with a proper example!