systemd

Pass credentials to a service: https://systemd.io/CREDENTIALS/
Socket activation
- systemd manages a socket and passes it to a service or starts a new instance of the service for each connection
- https://www.freedesktop.org/software/systemd/man/systemd.socket.html
- https://vincent.bernat.ch/en/blog/2018-systemd-golang-socket-activation
11 unit types:
- service units control daemons
- socket units for socket activation
- target units for grouping/dependency selection
- device units for device-based activation
- mount units control mount points (does this augment or replace /etc/fstab?)
- automount units to auto-mount filesystems/parallel boot
- timer units to trigger other units on a timer/schedule
- swap units are like mount units but for swap partitions/files
- path units to activate other units when a file is modified
- slice units to group other units in a tree (for resource management)
- scope units are like slices but for non-systemd processes
The default.target unit is activated on boot, which starts everything else via dependencies
Each unit gets its own cgroup
Cycle detection when a unit is started
Service types: simple, exec, forking, oneshot, dbus, notify or idle
systemd cat <unit> to print the unit source
systemd edit <unit> to add an override
systemd edit -full <unit> to edit a the original service
systemd-nspawn to run a command in a container