[Solved] You wrote this Dockerfile snippet:FROM alpine USER appuser CMD ["sh"]But when running the container, you get a permission denied error. What is the likely cause? | Docker

Docker - Security

You wrote this Dockerfile snippet:

FROM alpine
USER appuser
CMD ["sh"]

But when running the container, you get a permission denied error. What is the likely cause?

AThe CMD syntax is incorrect

BThe user 'appuser' does not exist in the image

CThe base image alpine does not support USER

DThe container needs root to run sh

Step-by-Step Solution

Solution:

Step 1: Check if user exists in image
The USER appuser requires that 'appuser' is created in the image, otherwise permission errors occur.
Step 2: Verify other options
CMD syntax is correct, alpine supports USER, and sh can run as non-root if permissions allow.
Final Answer:
The user 'appuser' does not exist in the image -> Option B
Quick Check:
User must exist = B [OK]

Quick Trick: Create user before USER instruction to avoid permission errors [OK]

Common Mistakes:

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