Issue Summary

• Occasionally, users report that they receive the following error when executing their runner builds:

  bash: docker: command not found
  

• This issue is caused by the local Runner directory /tmp/<runner_uuid>/ already containing an empty docker folder.
• We are not yet sure why the Runner directory sometimes already contains an empty docker folder (theory is that it's because of an unsuccessful runner configuration that has not cleaned itself up)
• Since the docker folder already exists, the Runner fails to mount the new docker directory and the docker binary won't be present during the build.

This is reproducible on Data Center: no

Steps to Reproduce

1. Execute a build within a dockerized Self-hosted Runner
2. Observe the error that occurs (this is intermittent - hard to reproduce)

Expected Results

• The build is able to execute

Actual Results

• The build fails as it is unable to mount the directory

Workaround

• The workaround is described in the following article:
  https://confluence.atlassian.com/bbkb/docker-command-not-found-error-while-running-docker-commands-in-self-hosted-runner-1206785605.html