.dockerignore is ignored when build context is a remote git repo

Image Builds
1

When I build an image from the local directory COPY . . in the Dockerfile copies all files except those listed in .dockerignore.
But when I build an image it by providing the URL to a git repo I have on codeberg, all files are copied, as if the .dockerignore file didn’t exist.
Is this expected behavior or a bug?
Thanks.

2

Sicne the dockerignore file should be in the build context, when your build context is remote, your dockerignore file should also be remote.

https://docs.docker.com/build/concepts/context/#filename-and-location

If you only want to use the Dockerfile and not the whole project, then you can directly refer to the Dockerfile like this:

docker built -f https://raw.githubusercontent.com/emmanuelgautier/awesome-dockerfiles/refs/heads/main/go/Dockerfile . -t localhost/imagename

And make sure that the required files are available locally in the local build context.

3

But my .dockerignore file is in the remote git repo, right next to the Dockerfile.
Please watch my asciinema video and feel free to test it yourself.
https://asciinema.org/a/STrRUPglziIu12wP
Thanks.

4

After wasting more time than I’d like to admit, I learned here that the .dockerignore file in the git repo is ignored. As a result, the whole git repo ends up in the build context. The only place where this is mentioned, though, is the github issue linked above :person_shrugging:
The official docs say quite the opposite! :angry:

You can use a .dockerignore file to exclude files or directories from the build context.
[…]
This helps avoid sending unwanted files and directories to the builder, improving build speed, especially when using a remote builder.

5

A remote builder is just another buildkit instance on a remote host. It is not related to a remote context source.

I am missing the information here,. This should mention the constraint it applies to.

Update: my last sentence is ambiguous. I would expect to find that kind of information in the docs. Currently it is not addressed in the docs.

6

Thanks for sharing it. It should indeed be mentioned in the documentation. If it is, I could not find it either.