Docker for Rails Developers

File Ownership and Permissions

There are some subtle differences when it comes to how file ownership and permissions are handled on the different Docker platforms (Mac, Linux, and Windows). These differences can cause a slight issue when you write files to a mounted volume from inside a container.

The issue stems from the fact that there are usually different user accounts being used inside and outside a container. Typically, you use your normal user account on your machine, but inside a container, the default user is the container’s root account. This means that files created inside the container are owned by that root user.

When you exit the container, the question is, will you be able to modify these files that are owned by root? The answer ...