TL;DR: You probably never need to touch systemd services and you should really use the ForemCTL instead
When you have a program or application you want to run on Linux, its a common practice to create a systems service which is a fancy script that allows you to start, stop, restart or get the status of a service.
A service just means a program or app that runs in the background awaiting to accept work to do.
Selfhost uses Fedora CoreOS (FCOS) and FCOS uses SystemD.
What is SystemD?
SystemD is a System and service manager. You can define a service with a .service file and then can perform tasks like:
sudo systemctl restart httpd.service
sudo systemctl stop httpd.service
sudo systemctl start httpd.service
sudo systemctl status httpd.service
Where are the SystemD services defined?
Within selfhost if you open up the buntane file at playbooks/templates/forem.yml.j2
You can see the SystemD services defined:
systemd:
units:
- name: forem-pod.service
enabled: true
contents: |
[Unit]
Description=Forem pod service
Wants=network.target
After=network-online.target forem-container.service
Wants=forem-postgresql.service forem-redis.service forem.service forem-traefik.service
Before=forem-postgresql.service forem-redis.service forem-openresty.service forem.service
[Service]
LimitNOFILE=1048576
Environment=PODMAN_SYSTEMD_UNIT=%n
Restart=on-failure
ExecStartPre=-/usr/bin/podman pod create \
--infra-conmon-pidfile %T/%N.pid \
--name %N \
-p 443:443 -p 80:80
ExecStart=/usr/bin/podman pod start %N
ExecStop=/usr/bin/podman pod stop -t 10 %N
ExecStopPost=/usr/bin/podman pod stop -t 10 %N
ExecStopPost=/usr/bin/podman pod rm %N
PIDFile=%T/%N.pid
KillMode=none
Type=forking
SyslogIdentifier=%N
[Install]
WantedBy=multi-user.target default.target
How to view all services on your Forem server
There can be many services on your Forem server, and easy way to see a full of them is the following command:
list-units --type=service
UNIT LOAD ACTIVE SUB DESCRIPTION
chronyd.service loaded active running NTP client/server
console-login-helper-messages-gensnippet-os-release.service loaded active exited Generate os release snippet for display via console-login-helper-messages
console-login-helper-messages-gensnippet-ssh-keys.service loaded active exited Generate SSH keys snippet for display via console-login-helper-messages
dbus-broker.service loaded active running D-Bus System Message Bus
dracut-shutdown.service loaded active exited Restore /run/initramfs on shutdown
fcos-python-3.service loaded active exited FCOS Python 3 service
fedora-coreos-pinger.service loaded active exited Telemetry service for Fedora CoreOS
forem-imgproxy.service loaded active running Forem Imgproxy Service
forem-openresty.service loaded active running Forem OpenResty Service
forem-pod.service loaded active running Forem pod service
forem-postgresql.service loaded active running Forem Postgresql Service
forem-rails.service loaded active running Forem Rails Service
forem-redis.service loaded active running Forem Redis Service
forem-traefik.service loaded active running Forem Traefik Service
forem-worker.service loaded active running Forem Worker Service
forem.service loaded active exited Forem Service
getty@tty1.service loaded active running Getty on tty1
irqbalance.service loaded active running irqbalance daemon
kmod-static-nodes.service loaded active exited Create List of Static Device Nodes
ldconfig.service loaded active exited Rebuild Dynamic Linker Cache
lvm2-monitor.service loaded active exited Monitoring of LVM2 mirrors, snapshots etc. using dmeventd or progress polling
NetworkManager-wait-online.service loaded active exited Network Manager Wait Online
NetworkManager.service loaded active running Network Manager
ostree-remount.service loaded active exited OSTree Remount OS/ Bind Mounts
polkit.service loaded active running Authorization Manager
serial-getty@ttyS0.service loaded active running Serial Getty on ttyS0
sshd.service loaded active running OpenSSH server daemon
sssd.service loaded active running System Security Services Daemon
systemd-fsck@dev-disk-by\x2dlabel-boot.service loaded active exited File System Check on /dev/disk/by-label/boot
systemd-homed-activate.service loaded active exited Home Area Activation
systemd-homed.service loaded active running Home Area Manager
systemd-hwdb-update.service loaded active exited Rebuild Hardware Database
systemd-journal-catalog-update.service loaded active exited Rebuild Journal Catalog
systemd-journal-flush.service loaded active exited Flush Journal to Persistent Storage
systemd-journald.service loaded active running Journal Service
You can see there are alot of services. Most of these came with Fedora CoreOS.
The ones that were setup by forem all start with forem- so we can use grep to just see these services:
systemctl list-units --type=service | grep forem
which will produce:
forem-imgproxy.service loaded active running Forem Imgproxy Service
forem-openresty.service loaded active running Forem OpenResty Service
forem-pod.service loaded active running Forem pod service
forem-postgresql.service loaded active running Forem Postgresql Service
forem-rails.service loaded active running Forem Rails Service
forem-redis.service loaded active running Forem Redis Service
forem-traefik.service loaded active running Forem Traefik Service
forem-worker.service loaded active running Forem Worker Service
forem.service loaded active exited Forem Service
When would we want to mess with SystemD services?
There are rare cases where you need to go in and restart a service, but generally starting, stoping and restarting services would be if you had a deployment pipeline.
If you need to do a sanity check to make sure your Rails, Postgres, Redis or Sidekiq service is running you would check its status:
sudo systemctl status forem-rails
● forem-rails.service - Forem Rails Service
Loaded: loaded (/etc/systemd/system/forem-rails.service; enabled; vendor preset: enabled)
Active: active (running) since Thu 2021-07-22 19:48:40 UTC; 38min ago
Process: 2955 ExecStartPre=/usr/bin/podman image exists localhost/forem/forem:current (code=exited, status=0/SUCCESS)
Process: 2985 ExecStartPre=/usr/bin/podman run --name forem-rails-bootstrap --pod forem-pod --log-driver journald --replace --rm --sdnotify ignore --env-file /opt/forem/env>
Main PID: 3132 (conmon)
Tasks: 2 (limit: 2239)
Memory: 52.6M
CPU: 3.637s
CGroup: /machine.slice/machine-forem.slice/machine-forem-pod.slice/forem-rails.service
└─3132 /usr/bin/conmon --api-version 1 -c d7bdd1f6baae5ee03b2798c91ccf9795d04e51a53bf0293968461143fa470253 -u d7bdd1f6baae5ee03b2798c91ccf9795d04e51a53bf0293968461>
Jul 22 20:07:10 www.thedev.cloud conmon[3132]: I, [2021-07-22T20:07:10.242930 #7] INFO -- : [191d47a8-969e-4031-830a-a635506fbc38] Parameters: {"locale"=>nil}
Jul 22 20:07:10 www.thedev.cloud conmon[3132]: I, [2021-07-22T20:07:10.292204 #7] INFO -- : [191d47a8-969e-4031-830a-a635506fbc38] Rendered devise/registrations/new.html.erb>
Jul 22 20:07:10 www.thedev.cloud conmon[3132]: I, [2021-07-22T20:07:10.564313 #7] INFO -- : [191d47a8-969e-4031-830a-a635506fbc38] Rendered layout layouts/application.html.e>
Jul 22 20:07:10 www.thedev.cloud conmon[3132]: I, [2021-07-22T20:07:10.564739 #7] INFO -- : [191d47a8-969e-4031-830a-a635506fbc38] Filter chain halted as :verify_private_forem>
Jul 22 20:07:10 www.thedev.cloud conmon[3132]: I, [2021-07-22T20:07:10.565142 #7] INFO -- : [191d47a8-969e-4031-830a-a635506fbc38] Completed 200 OK in 322ms (Views: 295.1ms | >
Jul 22 20:07:10 www.thedev.cloud conmon[3132]: I, [2021-07-22T20:07:10.597743 #8] INFO -- : [ca2ed591-22bf-4516-91f8-1d4040e16114] Started GET "/sitemaps/sitemap.xml.gz" for 6>
Jul 22 20:07:10 www.thedev.cloud conmon[3132]: F, [2021-07-22T20:07:10.640000 #8] FATAL -- : [ca2ed591-22bf-4516-91f8-1d4040e16114]
Jul 22 20:07:10 www.thedev.cloud conmon[3132]: [ca2ed591-22bf-4516-91f8-1d4040e16114] ActionController::RoutingError (No route matches [GET] "/sitemaps/sitemap.xml.gz"):
Jul 22 20:07:10 www.thedev.cloud conmon[3132]: [ca2ed591-22bf-4516-91f8-1d4040e16114]
Jul 22 20:07:10 www.thedev.cloud conmon[3132]: E, [2021-07-2
Forem Control is way easier to use
The most common tasks related to services would be using foremctl
$ foremctl help
Usage: foremctl {console|deploy|help|rake|restart|start|stat|status|stop|update|version}
console Open a Rails console
deploy Updates and deploy the most current version of Forem
help Show this message
rake Run a rake task
restart Restart Forem
start Start Forem
stats Show CPU, RAM, Disk IO usage of the Forem containers
status Show the current running Forem containers
stop Stop Forem
update Updates Forem to the lastest container
version Shows information on the current running version of Forem
To get a bunch of stats of current services
$ foremctl stats
ID NAME CPU % MEM USAGE / LIMIT MEM % NET IO BLOCK IO PIDS
29a1cb7fe232 forem-imgproxy -- 42.04MB / 2.039GB 2.06% 77.78kB / 125.2kB 40.1MB / 0B 8
2fa68d8d5c2b forem-openresty -- 11.33MB / 2.039GB 0.56% 77.78kB / 125.2kB 8.413MB / 12.29kB 4
4e2db20b2690 forem-traefik -- 16.8MB / 2.039GB 0.82% 77.78kB / 125.2kB 8.192kB / 20.48kB 10
94977d75c1ce forem-postgresql -- 85.6MB / 2.039GB 4.20% 77.78kB / 125.2kB 36.28MB / 68.75MB 8
9bc4592eeb54 forem-redis 0.23% 11.11MB / 2.039GB 0.54% 77.78kB / 125.2kB 11.38MB / 8.914MB 6
d7bdd1f6baae forem-rails 0.01% 411.5MB / 2.039GB 20.18% 77.78kB / 125.2kB 29.72MB / 9.077MB 29
e5712942bcb9 ff711bf9eef1-infra -- 749.6kB / 2.039GB 0.04% 77.78kB / 125.2kB 675.8kB / 0B 1
e990ee4624ea forem-worker 7.22% 345.8MB / 2.039GB 16.96% 77.78kB / 125.2kB 4.289MB / 7.807MB 10
Conclusion
You probably never want to touch these, in case of rare debugging cases.
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