"[file-log] failed to open the file: Permission denied" error when logging to /dev/stdout as a non-root user

We are trying to deploy the file-log plugin with the path defined as /dev/stdout. However, we are running into the following error:

[file-log] failed to open the file: Permission denied while logging request

When checking the permissions we don’t see anything that is lacking.

ls -al /dev/stdout
lrwxrwxrwx 1 root root 15 Mar 13 13:22 /dev/stdout -> /proc/self/fd/1

The file-log plugin documentation shows that logging to /dev/stdout is supported, but running the plugin this way produces a permissions error.

It is possible to configure the file-log plugin to /dev/stdout. The issue here is that the worker permissions are locked down.

/dev/stdout is owned by kong with 700 permissions so root cannot write to that dir.

This will happen if the user is switched to root in a Dockerfile. The way to resolve this is by changing the user back to kong. In your Dockerfile we need to add the following:

USER kong

After this we need to re-create the image and then re-deploy kong with the updated image.

Rerun the file-log plugin now, and the issue will be resolved.