[bug] docker runner doesn't work when conanfile is inside subfolder

[aagor]

Describe the bug

Environment details:

• OS: Linux
• Conan version: 2.12.1
• Conan profile: nothing special, use docker runner as described here

When using the docker runner, only the current directory get's mapped into the container.
This is not sufficient when the Conanfile is in a subfolder like in this example: Declaring the layout when the Conanfile is inside a subfolder.
Conan then can't access the root folder, as it's not mapped into the container and therefore fails to access files, leading to a build fail.

How to reproduce it

$ git clone https://github.com/conan-io/examples2.git
$ cd examples2/examples/conanfile/layout/conanfile_in_subfolder/conan
$ conan create .
> Build fails here
$ docker inspect conan-runner-docker |jq .[].HostConfig.Binds

jq output:

[
  "/home/<username>/examples2/examples/conanfile/layout/conanfile_in_subfolder/conan:/root/conanrunner/conan:rw"
]

[perseoGI]

Hi @aagor thank you for your report!
That is definitely a great catch!

We are improving the conan runners, I'll include a workaround for this issue in #17542
Stay tuned for incoming updates.
I'll inform here when this problem is addressed

Happy coding 🐸

[perseoGI]

Greetings @aagor,

I've been discussing with the team and we are considering giving support to this specific case.
The docker runner only mounts the directory where the conanfile.py file resides.
Mounting parent directories automatically is currently not supported.

But here is a quick workaround to address this issue:

1. Edit your docker profile adding a configfile key:

[runner]
type=docker
...
configfile=<absolute_path>/configfile.yml

2. Create a configfile.yml following the schema specified here: https://containers.dev/implementors/json_reference/

run:
    mounts:
        <absolute_path>/examples2/examples/conanfile/layout/conanfile_in_subfolder/:
            bind: /root/conanrunner/   # This is the mount folder inside the docker runner -> kind of internal to conan...
            mode: rw

3. Execute conan create again and this time should work.

I hope it helps!

[aagor]

Hi,
I can confirm that the workaround works.
Thanks.

[perseoGI]

Hi there!
I'm glad to hear it helps!

I'm introducing some changes and tests on the incoming runners to support this kind of project where conanfile is inside a subfolder.