Cirrus: Add gitlab podman runner test

Add execution of the downstream gitlab-runner tests using
rootless podman through the magic of socket-level
docker compatibility.  Include a comment suggesting how
to temporarily disable the test in case it fails beyond
podman code scope.

Signed-off-by: Chris Evich <cevich@redhat.com>

contrib/cirrus/runner.sh

@@ -286,6 +286,23 @@ function _run_release() {
     msg "All OK"
 }
 
+
+function _run_gitlab() {
+    rootless_uid=$(id -u)
+    systemctl enable --now --user podman.socket
+    export DOCKER_HOST=unix:///run/user/${rootless_uid}/podman/podman.sock
+    export CONTAINER_HOST=$DOCKER_HOST
+    cd $GOPATH/src/gitlab.com/gitlab-org/gitlab-runner
+    set +e
+    go test -v ./executors/docker |& tee $GOSRC/gitlab-runner-podman.log
+    ret=$?
+    set -e
+    # This file is collected and parsed by Cirrus-CI so must be in $GOSRC
+    cat $GOSRC/gitlab-runner-podman.log | \
+        go-junit-report > $GOSRC/gitlab-runner-podman.xml
+    return $ret
+}
+
 logformatter() {
     if [[ "$CI" == "true" ]]; then
         # Use similar format as human-friendly task name from .cirrus.yml

contrib/cirrus/setup_environment.sh

@@ -243,6 +243,44 @@ case "$TEST_FLAVOR" in
 
         install_test_configs
         ;;
+    gitlab)
+        # This only runs on Ubuntu for now
+        if [[ "$OS_RELEASE_ID" != "ubuntu" ]]; then
+            die "This test only runs on Ubuntu due to sheer laziness"
+        fi
+
+        # Ref: https://gitlab.com/gitlab-org/gitlab-runner/-/issues/27270#note_499585550
+
+        remove_packaged_podman_files
+        make install PREFIX=/usr ETCDIR=/etc
+
+        # Need to re-build lists (removed during image production)
+        ooe.sh apt-get -qq -y update
+        msg "Installing previously downloaded/cached packages"
+        # N/B: Tests check/expect `docker info` output, and this `!= podman info`
+        ooe.sh apt-get install --yes --no-download --ignore-missing containerd.io docker-ce docker-ce-cli
+
+        msg "Disabling docker service and socket activation"
+        systemctl stop docker.service docker.socket
+        systemctl disable docker.service docker.socket
+        rm -rf /run/docker*
+        # Guarantee the docker daemon can't be started, even by accident
+        rm -vf $(type -P dockerd)
+
+        msg "Obtaining necessary gitlab-runner testing bits"
+        slug="gitlab.com/gitlab-org/gitlab-runner"
+        helper_fqin="registry.gitlab.com/gitlab-org/gitlab-runner/gitlab-runner-helper:x86_64-latest-pwsh"
+        ssh="ssh $ROOTLESS_USER@localhost -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -o CheckHostIP=no env GOPATH=$GOPATH"
+        showrun $ssh go get -u github.com/jstemmer/go-junit-report
+        showrun $ssh git clone https://$slug $GOPATH/src/$slug
+        showrun $ssh make -C $GOPATH/src/$slug development_setup
+        showrun $ssh bash -c "'cd $GOPATH/src/$slug && GOPATH=$GOPATH go get .'"
+
+        showrun $ssh podman pull $helper_fqin
+        # Tests expect image with this exact name
+        showrun $ssh podman tag $helper_fqin \
+            docker.io/gitlab/gitlab-runner-helper:x86_64-latest-pwsh
+        ;;
     swagger) ;&  # use next item
     consistency) make clean ;;
     release) ;;