Avoid EACCES error in actor builds with a custom Dockerfile

Sometimes when building an actor using a custom Dockerfile, you might receive errors like:

Missing write access to ...

or

EACCES: permission denied

This problem is usually caused by the fact that by default, the COPY Dockerfile instruction copies files as the root user (with UID and GID of 0), while your Dockerfile probably uses another user to copy files and run commands.

To fix this problem, make sure the COPY  instruction in Dockerfile uses the --chown flag. For example, instead of

COPY . ./

use

COPY --chown=myuser:myuser . ./

where myuser is the user and group defined by the USER  instruction in the base Docker image. To learn more, see Dockerfile documentation.

Hope this helps!