included-as-non-root

Running cypress/included image as non-root

Running as root

Whenever you run tests using cypress/included:... image, it runs as root user

$ docker run -it -v $PWD/src:/test -w /test --entrypoint whoami cypress/included:3.8.0
root
$ docker run -it -v $PWD/src:/test -w /test cypress/included:3.8.0
...

Root vs non-root user

You can determine if you are a root user inside a container using Node and printing

process.geteuid()
// 0 - root user
// non zero - non-root user

As a single line

$ node -p 'process.geteuid()'

From shell, you can print user id via id command

$ id
uid=0(root) gid=0(root) groups=0(root)

Run as non-root

If you try to run cypress/included image as another user, for example node you hit problems

$ docker run -it -v $PWD/src:/test -w /test -u node cypress/included:3.8.0
The cypress npm package is installed, but the Cypress binary is missing.

We expected the binary to be installed here: /home/node/.cache/Cypress/3.8.0/Cypress/Cypress

You can see the user id when running as -u node by opening shell

$ docker run -it -v $PWD/src:/test -w /test -u node --entrypoint /bin/sh cypress/included:3.8.0
$ id
uid=1000(node) gid=1000(node) groups=1000(node)

Solution

You need to build your own Docker image on top of the desired cypress/included:... image where you change the user. Before changing from root to node you need to move the cache folder though - to give node user access to it. See Dockerfile in the current folder.

FROM cypress/included:3.8.0

# "root"
RUN whoami

# there is a built-in user "node" that comes from the very base Docker Node image
# move test runner binary folder to the non-root's user home directory
RUN mv /root/.cache /home/node/.cache

USER node
# show user effective id and group - it should be non-zero
# meaning the current user "node" is not root
RUN id

You can build the above image using build.sh, which names it cypress/example. Now run the tests as non-root user node - it should work.

$ docker run -it -v $PWD/src:/test -w /test -u node cypress/example
Running tests against cypress/example
...

Good read Use non-root user inside Docker container and Processes In Containers Should Not Run As Root