Quadlet

Quadlet is a tool for generating systemd services from podman containers.
You can also describe a project as a podman-compose project, and generate systemd services for it as well.

The goal for the project is to be concise and change tolerant with sane defaults.

Documentation

man quadlet / podman-systemd.unit (incl. filetypes/opts)	https://man.archlinux.org/man/quadlet.5.en
official multi-container tutorial	https://www.redhat.com/sysadmin/multi-container-application-podman-quadlet
src	https://github.com/containers/podman/tree/main/pkg/systemd/quadlet

Tutorials

https://mo8it.com/blog/quadlet/

intro

Locations

~/.config/containers/systemd/*.{kube,container,volume,network,yml}	build systemd services from these
/usr/libexec/podman/quadlet	quadlet executable (not on path)

Usage

Overview

While quadlet is technically an executable, it's designed to work with systemd commands directly.

After adding your files to ~/.config/containers/systemd/*.{kube,container,volume,network,yml},
you can run daemon-reload and your generated systemd services will be made available.

Here's the TL;DR from the official tutorial:

mkdir -p $HOME/.config/containers/systemd/
cp envoy-proxy-configmap.yml \
   quadlet-demo.kube \
   quadlet-demo-mysql.container \
   quadlet-demo-mysql.volume \
   quadlet-demo.network \
   quadlet-demo.yml \
   $HOME/.config/containers/systemd/
systemctl --user daemon-reload
systemctl --user start quadlet-demo.service

You can debug the generated files using

/usr/libexec/podman/quadlet --dryrun

Secrets

It looks like these are primarily managed using kubernetes own utils from kubectl create secret ${secret}.

TODO:

more research is needed here.

Syntax

Overview

# systemd unitfile generator files
*.container: for a single container                        # podman run
*.kube:      from kubernetes yaml files using              # podman kube play
*.pod:       for a single pod within kubernetes yaml files # ? is this correct?
*.yml:       a kubernetes yaml file

# resources
*.image:     ensures a docker image is pulled
*.network:   create podman networks, referenced in '.container' or '.kube' files
*.volume:    create podman volumes, referenced in '.container' files

Standalone Containers

*.container

# ~/.config/containers/systemd/foo.container

[Install]
WantedBy=default.target

[Container]
Image=docker.io/library/mysql:5.6
ContainerName=foo
Volume=foo.volume:/var/lib/mysql
Network=foo.network

Kubernetes

*.yml

A kubernetes yaml file.

# ~/.config/containers/systemd/foo.yml
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: wp-pv-claim
  labels:
    app: wordpress
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 20Gi
---
apiVersion: v1
kind: Pod
metadata:
  name: quadlet-demo
spec:
  containers:
  - name: wordpress
    image: docker.io/library/wordpress:4.8-apache
    env:
    - name: WORDPRESS_DB_HOST
      value: quadlet-demo-mysql
    - name: WORDPRESS_DB_PASSWORD
      valueFrom:
        secretKeyRef:
          name: mysql-root-password-kube
          key: password
    volumeMounts:
    - name: wordpress-persistent-storage
      mountPath: /var/www/html
# ... etc ...

*.pod

Abstraction of a systemd unit file for running specific kubernetes pods only.

TODO:

is this understanding correct?

*.kube

Abstraction of a systemd unit file for running an entire kubernetes project

Resources

*.network

Define a network to share between multiple containers.

# ~/.config/containers/systemd/foo.network

Subnet=192.168.30.0/24
Gateway=192.168.30.1

would generate

podman-network: systmd-foo            # podman network create systemd-foo
systemd-unit:   foo-network.service

*.volume

Describe a volume to share between multiple containers.

*.image

Ensure a docker image is pulled.
Generates a service that can be used as a dependency.