Aspier.Hosting.Dcp.dcpctrl.ContainerReconciler path error

[joshmouch]

Hi, I'm going outside the box a little here, and trying to override the otel collector the Aspire Dashboard/AppHost uses so that I can also share the collector with other processes.

When I get to the DistributedAppBuilder.AddResource()......WithVolume() part, I was expecting to be able to enter in docker volume info just like they would appear in a docker-compose.yaml file. At least in Visual Studio, if you have a docker-compose, relative paths in it will be relative to your Solution folder.

So here's what I'd like to pass into WithVolume():

.WithVolume("./Otel/Config", "/config")

However, I can't get past the following error. I've tried both absolute and relative paths, and I've tried them both with both backslashes and forward slashes.

Aspire.Hosting.Dcp.dcpctrl.ContainerReconciler[0]

      could not create the container    {"Container": {"name":"opentelemetrycollector"}, "Reconciliation": 2, "error": "CreateContainer command returned error code 1 Stdout: '' Stderr: 'Error response from daemon: create S:\\Source\\.....\\AppHost\\bin\\Debug\\net8.0\\Otel\\Config: \"S:\\\\Source\\\\......\\\\AppHost\\\\bin\\\\Debug\\\\net8.0\\\\Otel\\\\Config\" includes invalid characters for a local volume name, only \"[a-zA-Z0-9][a-zA-Z0-9_.-]\" are allowed. If you intended to pass a host directory, use absolute path\n'"}

[davidfowl]

There are 2 kinds of volumes, bind mounts and volumes. In this case you want a bind mount because you are trying to use mount a path from the host machine into the container. Call WithBindMount instead of WithVolume.

Also consider using PracticalOtel.OtelCollector.Aspire which already has this integration.

cc @martinjt

[joshmouch]

Thanks for the response. The package you mentioned does something similar, and throw the same exception if the files arguments are anything but a single level (no / allowed).

The WithBind and WithVolume have the same exception. I think I want the latter since the path doesn't exist in the containers image.

[davidfowl]

If you are trying to map files on your host into the container then you want a bind mount, not a volume.

[martinjt]

I'm not sure why you'd need more than just a file. What else is in the config directory? the collector only needs a single file.

So for the collector itself, providing the full path to the file should be sufficient.

[davidfowl]

@karolz-ms do we support directories with volumes?

[karolz-ms]

@davidfowl not sure what you mean by "directories with volumes", but a bind mount with a bunch of files should work just fine.

As the error message says, the host path needs to be absolute with the current version of the API, but as a workaround today, it should be relatively easy to make an absolute path out of a relative path in AppHost code, and we can consider adding an overload that does that (for some reasonable reference folder, e.g. solution folder like @joshmouch proposed) in future version of Aspire.

[joshmouch]

I'm not sure why you'd need more than just a file. What else is in the config directory? the collector only needs a single file.

Ask not why, but why not? :) Docker supports an entire folder. Visual Studio uses entire folders for its "fast docker debug mode". I intend to have a drop folder that the container will dump files to that can be analyzed after the run. I could spend some time and come up with dozens of use cases.
Is there a technical or design limitation that would make it easier to only target files?

[martinjt]

I'm specifically talking about the OpenTelemetry Collector rather than the generalised usecase of docker mounts.

[joshmouch]

As the error message says, the host path needs to be absolute with the current version of the API, but as a workaround today, it should be relatively easy to make an absolute path out of a relative path in AppHost code,

Are you referring to end user AppHost code? That's what I was trying to do but getting exceptions. I was assuming absolute to disk root, but it's not clear if that's the case. I did see some interesting paths in logs like "/run/mnt/desktop/c/etc..."... maybe not related.

[karolz-ms]

Yes, end user AppHost code, and yes, absolute path as in it does not rely on any notion of "current directory", "solution directory", or similar.

If you are getting errors with a bind mount using an absolute path, please open an issue, because that should work.

[davidfowl]

We fixed this in preview 6, we resolve the absolute path in the call to WithBindMount.