An overview of Systemd was provided in Chapter 1, CoreOS Overview. Systemd is the init system used by CoreOS and is always on by default. In this section, we will walk through some of the Systemd internals.
Units describe a particular task along with its dependencies and the execution order. Some units are started on the CoreOS system by default. CoreOS users can also start their own units. System-started units are at
/usr/lib64/systemd/system and user-started units are at
The following are some of the common unit types:
- Service unit: This is used to start a particular daemon or process. Examples are
sshd.serviceunit starts the SSH service, and
docker.servicestarts the ...