Accessing files in a buildah mount using a Dockerfile with --mount=type=cache results in a permission denied

Environment

• Red Hat Enterprise Linux (RHEL) 8.6
• Red Hat Openshift Container Platform (OCP) 4.10
• buildah 1.24.2
• Building with a docker file using cache mount type.

Issue

• All file actions result in permission denied.
• Examples that work with buildkit all fail

Resolution

This is still under investigation. See This content is not included.BZ 2111275

Diagnostic Steps

• A simple Dockerfile

    FROM ubi8/ubi
  
    RUN --mount=type=cache,target=/mycache  touch /mycache/myfile.txt
  

  fails with permission denied. Attempts to set user ids, change the permissions on the directory, etc, all fail with the same error.

• Running an strace on the file touch withing the buildah container doesn't yield any useful results

    FROM ubi8/ubi
    RUN yum install -y strace
    RUN --mount=type=cache,target=/mycache  strace touch /mycache/myfile.txt
  

  Output:

    ...
    write(2, "touch: ", 7touch: )                  = 7
    write(2, "cannot touch '/mycache/myfile.tx"..., 34cannot touch '/mycache/myfile.txt') = 34
    write(2, ": Permission denied", 19: Permission denied)     = 19
    write(2, "\n", 1
    ...
  

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