Mounting a writable volume on a Container without a writable file system

[scenic hatch]

I am trying to use a file exporter in otel/opentelemetry-collector-contrib, without success yet. The documentation says to do something like

# linux needs +x to list a directory.  You can use a+ instead of o+ for the mode if you want to ensure your user and group has access.
mkdir --mode o+rwx file-exporter
# z is an SELinux construct that is ignored on other systems
docker run -v "./file-exporter:/file-exporter:rwz" -v "otel-collector-config.yaml:/etc/otelcol-contrib/config.yaml" otel/opentelemetry-collector-contrib:latest

I tried using .with_mounted_cache but it did not work.

[plucky umbra]

@scenic hatch do you have any dagger code you can share to start from there? FWIW the scratch layer is effectively writable. What I think the doc is trying to say is that the collector doesn't create the directory by default, so you need to create it beforehand

here's an example on how you can use WithNewDirectory for that:

package main

import (
    "context"
)

type Scratch struct{}

func (m *Scratch) Test(ctx context.Context) []string {
    e, _ := dag.Container().WithDirectory("/somepath", dag.Directory().WithNewDirectory("")).Entries(ctx)
    return e
}

[plucky umbra]

^ you can also assign the required permissions in the WithNewDirectory call

[scenic hatch]

Example.

[plucky umbra]

👀

@scenic hatch here's the fix: