What is the purpose of Docker’s –read-only flag and how can applications that need to write data still function?

Question

Docker Fundamentals — Hard

What is the purpose of Docker’s –read-only flag and how can applications that need to write data still function?

Accepted Answer

The purpose of Docker's --read-only flag is to mount the container's root filesystem as read-only, preventing writes to the container layer. Applications needing to write data can utilize tmpfs mounts for temporary data and volumes for persistent data at specific writable paths.