Daemon¶

You can start your containers with run command but for following requirements suggested to use daemon service instead of standalone.

Automatically starting containers at the boot
Rerun container when process is exits
Work with read-only disk system and keep current state at memory
Reduce read and write calls to system disk for updating or getting state information

Registering the Service¶

Installation of daemon supports Systemd and Open RC init systems.

sandal daemon -install

You can start service with your system init and service controller.

managing

sh title="service control" annote
# service sandal [start|stop|restart]
service sandal start # (1)!

Output of service command varies between Systemd and OpenRC but it does not have impact.

Behaviors of Daemon Service¶

Service Start¶

Provisiones containers which they have a -d and --startup arguments placed while creating with sandal run command.

Service Stop¶

Daemon has signal proxy to transfer received following signals to containers.

SIGINT (2)
SIGQUIT (3)
SIGTERM (15)

If container does not gracefully shut down in 30 second when the signal is recived by contianer, daemon itself will send SIGKILL (9) to the container for ending the process.

Container Death¶

Health check function checks existence of container Process ID (PID), if not, it re-provisions container with same run arguments.

File Events at Sandal State Directory¶

In case of manual actions under Sandal state directly, system reads those actions and reloads files into daemon.
Note: File Events only supported physically attached storage systems. Network attached storage (SMB, NFS) does capable to send those events.