Main Features¶

Standalone services
The supervisor is able to run default services like httpd, mysql which are invoked with a command of the type:
$ service httpd start

Executable

The supervisor is able to run any executable program, not only standard services:

/opt/whatever/instance/bin/service --option 1 --other "foo bar" --config /opt/whatever/instance/etc/whatever.cfg

Dead or “hang” state handling

Something important is to be able to handle services in an apparently running state but which are hanging. This should be handled from the service startup script.
OTP hierarchy of services
Inspired by OTP supervisor it support hierarchies of services. Services should be grouped together acting as a single service to the parent.

A supervision tree is composed by supervisors and workers:
- workers are identified by xN, yN and zN.
- supervisors are identified by sX.

OTP strategies for handling services

Inspired by the OTP platform there are different strategies for handling group of services and their behavior.
Commands: start/stop/status/restart
Different commands can be specified to handle a service:
- start
- stop
- status
- restart (defaults to stop+start)
Ensure expected state
Each service should have an expected state. Possible states are:
- running: expect the service to be running fine
- stopped: the service should be disabled
Daemon mode

Supervisor is able to run in daemon mode continuously checking and applying the given configuration.
One shot mode

Supervisor can run in “one shot mode”, which means it goes through the services handling and then exit. In order to handle the strategies correctly the state of the services is stored in order to be read during the next execution.
Root not required

Supervisor does not require to be run as root user, it is able to run as any user of course limited by the user privileges.