Develop in Docker I: Virtualbox file syncing bug

Docker is a great tool for deployment. And I want to develop my Flask app in Docker so that I can get the same environments as the production environments.

Bug description

But I went into this bug:

  • When I first mount a directory into a container, everything works fine.
  • After I change some code, the container aborted with a syntax error.
  • Then I attach into the container and see what happened.
    • When I use vim to open the "syntax error" file, everything seems to be fine.
    • When I use cat to get the file content. Then change I made to this file appeared at the end of this file instead of the place I wanted it to be.

After some search, it seems to be a virtualbox bug:

But this bug may not appear on everyone's machine. At least in this post1, the speaker can get the file syncing correctly, I don't know if this is due to she didn't do any deletion. (If you are also interested in developing in Docker, you should read this post too)


The solution is simple:

Just don't use virtualbox as the docker running virtual machine. Use xhyve instead, which is also the VM used by the new Docker for Mac2. You can also check out this post3 about Docker for Mac.

And here is my post4 about using xhyve as the Docker client host VM.