Testcontainers with Podman in Java tests - testcontainers

Question

Is it possible to use Testcontainers with Podman in Java tests?
As of March 2022 Testcontainers library doesn't detect an installed Podman as a valid Docker environment.
Can Podman be a Docker replacement on both MacOS with Apple silicon (local development environment) and Linux x86_64 (CI/CD environment)?

Answer 1

It is possible to use Podman with Testcontainers in Java projects, that use Gradle on Linux and MacOS (both x86_64 and Apple silicon).
Prerequisites
Podman Machine and Remote Client are installed on MacOS - https://podman.io/getting-started/installation#macos
Podman is installed on Linux - https://podman.io/getting-started/installation#linux-distributions
Enable the Podman service
Testcontainers library communicates with Podman using socket file.
Linux
Start Podman service for a regular user (rootless) and make it listen to a socket:
systemctl --user enable --now podman.socket
Check the Podman service status:
systemctl --user status podman.socket
Check the socket file exists:
ls -la /run/user/$UID/podman/podman.sock
MacOS
Podman socket file /run/user/1000/podman/podman.sock can be found inside the Podman-managed Linux VM. A local socket on MacOS can be forwarded to a remote socket on Podman-managed VM using SSH tunneling.
The port of the Podman-managed VM can be found with the command podman system connection list --format=json.
Install jq to parse JSON:
brew install jq
Create a shell alias to forward the local socket /tmp/podman.sock to the remote socket /run/user/1000/podman/podman.sock:
echo "alias podman-sock=\"rm -f /tmp/podman.sock && ssh -i ~/.ssh/podman-machine-default -p \$(podman system connection list --format=json | jq '.[0].URI' | sed -E 's|.+://.+#.+:([[:digit:]]+)/.+|\1|') -L'/tmp/podman.sock:/run/user/1000/podman/podman.sock' -N core#localhost\"" >> ~/.zprofile
source ~/.zprofile
Open an SSH tunnel:
podman-sock
Make sure the SSH tunnel is open before executing tests using Testcontainers.
Configure Gradle build script
build.gradle
test {
OperatingSystem os = DefaultNativePlatform.currentOperatingSystem;
if (os.isLinux()) {
def uid = ["id", "-u"].execute().text.trim()
environment "DOCKER_HOST", "unix:///run/user/$uid/podman/podman.sock"
} else if (os.isMacOsX()) {
environment "DOCKER_HOST", "unix:///tmp/podman.sock"
}
environment "TESTCONTAINERS_RYUK_DISABLED", "true"
}
Set DOCKER_HOST environment variable to Podman socket file depending on the operating system.
Disable Ryuk with the environment variable TESTCONTAINERS_RYUK_DISABLED.
Moby Ryuk helps you to remove containers/networks/volumes/images by given filter after specified delay.
Ryuk is a technology for Docker and doesn't support Podman. See testcontainers/moby-ryuk#23
Testcontainers library uses Ruyk to remove containers. Instead of relying on Ryuk to implicitly remove containers, we will explicitly remove containers with a JVM shutdown hook:
Runtime.getRuntime().addShutdownHook(new Thread(container::stop));
Pass the environment variables
As an alternative to configuring Testcontainers in a Gradle build script, you can pass the environment variables to Gradle.
Linux
DOCKER_HOST="unix:///run/user/$UID/podman/podman.sock" \
TESTCONTAINERS_RYUK_DISABLED="true" \
./gradlew clean build -i
MacOS
DOCKER_HOST="unix:///tmp/podman.sock" \
TESTCONTAINERS_RYUK_DISABLED="true" \
./gradlew clean build -i
Full example
See the full example https://github.com/evgeniy-khist/podman-testcontainers

Answer 2

For Linux, it definitely work even though official testcontainers documentation is not really clear about it.
# Enable socket
systemctl --user enable podman.socket --now
# Export env var expected by Testcontainers
export DOCKER_HOST=unix:///run/user/${UID}/podman/podman.sock
export TESTCONTAINERS_RYUK_DISABLED=true
Sources:
https://quarkus.io/blog/quarkus-devservices-testcontainers-podman/
https://github.com/testcontainers/testcontainers-java/issues/2088#issuecomment-893404306

Answer 3

I was able to build on Evginiy's excellent answer, since Podman has improved in the time since the original answer. On Mac OS, these steps were sufficient for me and made testcontainers happy:
Edit ~/.testcontainers.properties and add the following line
ryuk.container.privileged=true
Then run the following
brew install podman
podman machine init
sudo /opt/homebrew/Cellar/podman/4.0.3/bin/podman-mac-helper install
podman machine set --rootful
podman machine start
If you don't want to run rootful podman, ryuk needs to be disabled:
export TESTCONTAINERS_RYUK_DISABLED="true"
Running without ryuk basically works, but lingering containers can sometimes cause problems and name collisions in automated tests. Evginiy's suggestion of a shutdown hook would resolve this, but would need code changes.

Answer 4

An add-on to #hollycummins answer. You can get it working without --rootful by setting the following environment variables (or their testcontainers properties counter part):
DOCKER_HOST=unix:///Users/steve/.local/share/containers/podman/machine/podman-machine-default/podman.sock`
TESTCONTAINERS_DOCKER_SOCKET_OVERRIDE=/var/run/user/501/podman/podman.sock
TESTCONTAINERS_RYUK_CONTAINER_PRIVILEGED=true
This will mount the podman socket of the linux VM into the Ryuk container. 501 is the UID of the user core in the linux VM user. See podman machine ssh.

Answer 5

if you running testcontainer build inside a docker container, alternatively you can start the service like this
podman system service -t 0 unix:///tmp/podman.sock &
OR
podman system service -t 0 tcp:127.0.0.1:19999 &