Setup for quadlet/systemd runtime management

Rather than setting up volumes and starting the pipglr container
manually, utilize quadlet + systemd.  Retain the old setup and execution
method, but move them into separate documentation.

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

quadlet/pipglr-cache.volume

@@ -0,0 +1,13 @@
+[Unit]
+Description=Podman-in-podman GitLab Runner job cache storage volume
+Documentation=https://gitlab.com/qontainers/pipglr/-/blob/main/README.md
+After=local-fs.target
+Requires=podman.socket
+
+[Volume]
+VolumeName=pipglr-cache
+Copy=false
+# The `podman` user inside the container should own everything
+Options=o=uid=1000,gid=1000
+# Support podman...prune --filters=persistent!=true
+Label=persistent=true

quadlet/pipglr-storage.volume

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+[Unit]
+Description=Podman-in-podman GitLab Runner nested-container storage volume
+Documentation=https://gitlab.com/qontainers/pipglr/-/blob/main/README.md
+After=local-fs.target
+Requires=podman.socket
+
+[Volume]
+VolumeName=pipglr-storage
+Copy=false
+# The `podman` user inside the container should own everything
+Options=o=uid=1000,gid=1000
+# Support podman...prune --filters=persistent!=true
+Label=persistent=true

quadlet/pipglr.container

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+[Unit]
+Description=Podman-in-podman GitLab Runner
+Documentation=https://gitlab.com/qontainers/pipglr/-/blob/main/README.md
+After=pipglr-storage-volume.service pipglr-cache-volume.service
+Requires=podman.socket pipglr-storage-volume.service pipglr-cache-volume.service
+
+[Container]
+ContainerName=pipglr
+Image=registry.gitlab.com/qontainers/pipglr
+
+# Required to run containers inside a container and ensure
+# container can be managed with podman-restart.service
+# Note: See https://github.com/containers/podman/issues/20418
+PodmanArgs=--privileged --restart=always
+
+# A nested systemd is used to manage nested podman & gitlab runner services
+Systemd=true
+
+# Allow jobs access to utilize fuse-overlayfs, for example to build container images.
+Device=/dev/fuse
+
+# Must be owned by the gitlab-runner user
+Secret config.toml,uid=1001,gid=1001
+
+# Add network isolation from other containers
+Network=pipglr.network
+
+# Storage for nested container images and job cache
+Volume=pipglr-storage:/home/podman/.local/share/containers
+Volume=pipglr-cache:/cache
+
+# No need to preserve this between runs
+VolatileTmp=true

quadlet/pipglr.network

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+[Unit]
+Description=Podman-in-podman GitLab Runner dedicated network
+Documentation=https://gitlab.com/qontainers/pipglr/-/blob/main/README.md
+After=network-online.target
+Requires=podman.socket network.target
+
+[Network]
+Driver=bridge
+# The pipglr container never accesses other containers on/or the host
+Options=isolate
+DisableDNS=true