[Solved] You run this command:docker run --read-only alpine sh -c "touch /tmp/testfile"But it fails with a permission error. What is the best fix? | Docker

Docker - Security

You run this command:
docker run --read-only alpine sh -c "touch /tmp/testfile"
But it fails with a permission error. What is the best fix?

ARemove the <code>--read-only</code> flag

BAdd a writable tmpfs mount for /tmp using <code>--tmpfs /tmp</code>

CRun the container as root user

DUse <code>-v /tmp:/tmp</code> to mount host /tmp

Step-by-Step Solution

Solution:

Step 1: Identify cause of permission error
The container filesystem is read-only, so creating files in /tmp fails.
Step 2: Provide writable space with tmpfs
Using --tmpfs /tmp mounts a writable temporary filesystem at /tmp, allowing file creation despite read-only root.
Final Answer:
Add a writable tmpfs mount for /tmp using --tmpfs /tmp -> Option B
Quick Check:
Writable tmpfs fixes write errors in read-only containers [OK]

Quick Trick: Use --tmpfs to add writable temp folders in read-only containers [OK]

Common Mistakes:

Master "Security" in Docker

9 interactive learning modes - each teaches the same concept differently

More Docker Quizzes

You run this command: