Docker based devstack fails to provision with self built docker images using configuration repo

Introduction

Deploying OpenEdX based environment requires rebuilding some images with small changes (i.e. changing email host, user etc. by defining relevant variables in ansible_overrides.yml). Image builds without any errors. However, provisioning fails, preventing to build the system gracefully.

Steps to Reproduce:

1. Clone open-release/hawthorn.master branch of devstack and _configuration _

2. Set environment variable for OPENEDX_RELEASE

3. Go to configuration repo directory and build edxapp image

4. Go to devstack repo directory, follow the instructions in readme

Expected Behavior:

Provision finishes successfully.

Current Behavior:

Provision fails with the following error:

Available workaround:

Running following command inside lms and studio containers then restarting provision bypasses the issue. Note that this is not the desired way of provisioning

Conclusion:

mysqlclient==1.4.2 is installed while building the docker image, probably its latest version as a part of requirement by some other dependency, since none of the requirement files includes it. It conflicts with original dependency of the system, mysql-python==1.2.5 which fails the provisioning