Pass in custom --build-args from .env* to a Dockerfile at buildtime

I have tried to use this pattern in lagoon, to allow a dockerfile to build from a specific image version.

ARG SOME_VERSION
FROM ourspace/nginx:${SOME_VERSION}

This works with docker-compose. The value is originally set in .env and passed in dynamically through docker-compose.yml, because it’s used multiple times). However in the lagoon build context there seems to be no way to set this as a --build-arg.

I think this is a feature request, but workaround suggestions are most welcome.

[bomoko]

I’m going to close this ticket for now, since we have workarounds for build vars and we have issue 1130 which, I think, covers the use case here. Happy to reopen if not.

[rocketeerbkw]

Well according to this article only docker-compose uses .env files natively. Docker doesn’t read them at all, but lagoon does and exposes them during the build process.

Having said that, the official docs do have an example like your code so maybe that’s not the problem.

The reason I thought it might be syntax error is cause the docs say the error for an unset ARG is

[Warning] One or more build-args [foo] were not consumed.

So perhaps it is a lagoon issue that we don’t expose .env as build-args.