`docker-compose.yml` example

[debuglevel]

As it took me quite a while to figure out the permission stuff how to run systemd_exporter with the docker image (https://hub.docker.com/r/prometheuscommunity/systemd-exporter), I would just like to document my solution here.

Typical errors were:

caller=systemd.go:247 level=error msg="error collecting metrics" err="couldn't get dbus connection: read unix @->/run/systemd/private: read: connection reset by peer"

caller=systemd.go:247 level=error msg="error collecting metrics" err="couldn't get dbus connection: write unix @->/run/systemd/private: write: broken pipe"

caller=collector.go:169 level=error msg="collector failed" name=systemd err="couldn't get dbus connection: dial unix /var/run/dbus/system_bus_socket: connect: no such file or directory"

couldn't get dbus connection: write unix @: sendmsg: broken pipe

version: '3.2'
services:
  node-exporter:
    container_name: systemd-exporter
    image: prometheuscommunity/systemd-exporter:v0.5.0
    command:
      - "--log.level=debug"
      - "--path.procfs=/host/proc"
      - "--web.listen-address=127.0.0.1:9558"
      - "--systemd.collector.private"  # Use systemd socket instead of DBus
    network_mode: "host"  # Does not need port specification therefore
    
    # We need either "privileged: true" (DBus connection) or "user: root" (systemd socket connection). Pick your poison.
    #privileged: true  # Needed to connect to DBus.
    user: "root"  # Needed to connect to systemd socket. 

    pid: "host"
    volumes:
      - type: "bind"
        source: "/proc"
        target: "/host/proc"
        read_only: true
      - type: "bind"
        source: "/run/systemd"
        target: "/run/systemd"
        read_only: true
      - type: "bind"
        source: "/var/run"
        target: "/var/run"
        read_only: true
      - type: "bind"
        source: "/sys/fs/cgroup"
        target: "/sys/fs/cgroup"
        read_only: true
    restart: unless-stopped

I'm not sure though if really all that binds are needed or could be at least a bit more specific (e.g. only /var/run/systemd/private).

[jantman]

This has been immensely helpful, thank you so much! Would be great if the maintainers looked this over for correctness, and added something to the examples...

[robinp]

Throwing in as a random data point, the following works, for some definition of works (dbus connection gets lost sporadically after hours/days, similar to prometheus/node_exporter#2500):

      "volumes": [
        "/var/run/dbus:/var/run/dbus:ro",
        "/run/dbus:/run/dbus:ro",
        "/run/systemd/private:/run/systemd/private:ro"
      ],