无法找到 root 用户：passwd 文件中没有匹配的条目

Question

I have a running Docker container with the following:

docker exec -it cc58908a8dc2 /bin/bash

I ran this command before on other containers and it worked just fine. Now, however, I'm getting this issue:

unable to find user root: no matching entries in passwd file

My Dockerfile has the following contents:

# We will be running our Spark jobs as `root` user.
USER root

# Working directory is set to the home folder of `root` user.
WORKDIR /root

Any idea of what could cause this?

Answer 1

Sometimes, after restarting the Docker container that message appears.

If instead of restarting like this: docker restart cc58908a8dc2

I stopped and started the container like this:

docker stop cc58908a8dc2
docker start cc58908a8dc2

Then the error disappeared.

Answer 2

If you want to get this fixed please remember to comment on https://forums.docker.com/t/unable-to-find-user-root-no-matching-entries-in-passwd-file/26545/9

Also use the feedback button from the KB article documenting how to restart docker engine when you encounter it: https://success.docker.com/article/ucp-health-checks-fail-unable-to-find-user-nobody-no-matching-entries-in-passwd-file-observed

It seems that the internet is full with others randomly encountering this bug.

To get an idea about which change you have to encounter it, take at look at http://status.openstack.org/elastic-recheck/index.html#1803544 which is a graph of bug occurence on OpenStack CI jobs, occurds daily.

I know that any software has bugs and that it takes time to fix them, but this bug left me.... more than two years old and the only feedback from Docker was "tracker privatly" and "restart docker".

Answer 3

Restarting containers usually helps (see @octavian answer). If it is not an option try:

docker exec -it -u 0 cc58908a8dc2 /bin/bash

where cc58908a8dc2 is the name of your container