Make Docker build stop after if RUN fails in multi-stage build

Question

I have a Dockerfile which has multiple stages. An intermediate stage runs tests. If the test fails, I would like the build to stop but it continues given below. You can see output where it continues beyond failed RUN command.

# Base image
FROM python:3.5 as base


# For running tests
FROM base
WORKDIR /root

RUN mkdir /root/src
ADD src/requirements.txt /root/src
RUN pip install -r /root/src/requirements.txt

ADD . /root
RUN ["/bin/bash", "-c", "cd test; ./run-tests.sh"]


# For publishing src files

FROM base
ADD src /root/src
ADD .pypirc /root/.pypirc


WORKDIR /root/src

CMD python setup.py sdist upload -r local

Output:

Step 6/13 : RUN pip install -r /root/src/requirements.txt
 ---> Using cache
 ---> 56fa7fc2f2e8
Step 7/13 : ADD . /root
 ---> 74c52977edcf
Step 8/13 : RUN ["/bin/bash", "-c", "cd test; ./run-tests.sh"]
 ---> Running in 68a184ab54af
...
----------------------------------------------------------------------
Ran 1 test in 10.122s

FAILED (failures=1)
The command '/bin/bash -c cd test; ./run-tests.sh' returned a non-zero code: 1
running sdist
running egg_info
...
running upload
Submitting dist/<artifact-name>-2.6.1.2.tar.gz to https://<subdomain>.jfrog.io/<context>/api/pypi/python-local
...

Answer 1

Your command, run-tests.sh, needs to exit with a non-zero exit code and docker will stop building. In this case, that has happened:

The command '/bin/bash -c cd test; ./run-tests.sh' returned a non-zero code: 1

Whatever you run to call docker build needs to handle that exit code and stop running at that point. Docker's behavior is to give you an exit code to indicate the failure:

$ cat df.fail
FROM busybox
RUN exit 1
RUN echo still running

$ docker build -f df.fail .
Sending build context to Docker daemon  23.04kB
Step 1/3 : FROM busybox
 ---> 59788edf1f3e
Step 2/3 : RUN exit 1
 ---> Running in 70d90fb88d6e
The command '/bin/sh -c exit 1' returned a non-zero code: 1

$ echo $?
1

From the above example, you can see that docker does stop as soon as the command returns a non-zero exit code, it does not run the echo still running line, and there's a non-zero return code from docker build itself that you can handle with whatever you use to run the build.