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Comment by kosolam | Hacker News Reader

This approach is akin to the prod server pulling an image from a registry. The op method is push based.

No, in my example the docker-compose.yml would exist alongside your application's source code and you can use the `build` directive https://docs.docker.com/reference/compose-file/services/#bui... to instruct the remote host (Hetzner VPS, or whatever else) to build the image. That image does not go to an external registry, but is used internal to that remote host.

For 3rd party images like `postgres`, etc., then yes it will pull those from DockerHub or the registry you configure.

But in this method you push the source code, not a finished docker image, to the server.

Seems like it makes more sense to build on the build machine, and then just copy images out to PROD servers. Having source code on PROD servers is generally considered bad practice.

The source code does not get to the filesystem on the prod server. It is sent to the Docker daemon when it builds the image. After the build ends, there's only the image on the prod server.

I am now convinced that this is a hidden docker feature that too many people aren't aware of and do not understand.

Yeah, I definitely didn't understand that! Thanks for explaining. I've bookmarked this thread, because there's several commands that look more powerful and clean than what I'm currently doing which is to "docker save" to TAR, copy the TAR up to prod and then "docker load".

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