This is likely a standard task, but I've spent a lot of time googling and prototyping this without success.
I want to set up CI for a Java application that needs a database (MySQL/MariaDB) for its tests. Basically, just a clean database where it can write to. I have decided to use Jenkins for this. I have managed to set up an environment where I can compile the application, but fail to provide it with a database.
What I have tried is to use a Docker image with Java and MariaDB. However, I run into problems starting MariaDB daemon, because at that point Jenkins already activates its user (UID 1000), which doesn't have permissions to start the daemon, which only the root user can do.
My Dockerfile:
FROM eclipse-temurin:17-jdk-focal
RUN apt-get update \
&& apt-get install -y git mariadb-client mariadb-server wget \
&& apt-get clean
COPY ./docker-entrypoint.sh /
ENTRYPOINT ["/docker-entrypoint.sh"]
The docker-entrypoint.sh is pretty trivial (and also chmod a+x'd, that's not the problem):
#! /bin/sh
service mysql start
exec "$@"
However, Jenkins fails with these messages:
$ docker run -t -d -u 1000:1001 [...] c8b472cda8b242e11e2d42c27001df616dbd9356 cat
$ docker top cbc373ea10653153a9fe76720c204e8c2fb5e2eb572ecbdbd7db28e1d42f122d -eo pid,comm
ERROR: The container started but didn't run the expected command. Please double check your ENTRYPOINT does execute the command passed as docker run argument, as required by official docker images (see https://github.com/docker-library/official-images#consistency for entrypoint consistency requirements).
Alternatively you can force image entrypoint to be disabled by adding option `--entrypoint=''`.
I have tried debugging this from the command line using the built Docker image c8b472cda8b. The problem is as described before: because Jenkins passes -u 1000:1001 to Docker, docker-entrypoint.sh script no longer runs as root and therefore fails to start the daemon. Somewhere in Docker or Jenkins the error is "eaten up" and not shown, but basically the end result is that mysqld doesn't run and also it doesn't get to exec "$@".
If I execute exactly the same command as Jenkins, but without -u ... argument, leaving me as root, then everything works fine.
I'm sure there must be a simple way to start the daemon and/or set this up somehow completely differently (external database?), but can't figure it out. I'm practically new to Docker and especially to Jenkins.