SYSMGR
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sysmgr is a service manager that aims to do as little as possible for service
supervision. It can be viewed as a simplified version of [runit]. It only cares
about making sure certain processes are alive unless explicitly stopped. Unlike
runit, it doesn't care about logging, or stopping daemons with special commands,
as those can easily be handled by service scripts themselves. It doesn't have
supervise directories with FIFOs inside. It _ONLY_ cares about processes and
nothing else.

[runit]: http://smarden.org/runit


Interacting with sysmgr
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While sysmgr can be interacted entirely with POSIX base tools, sysmgr provides
a tool named 'svctl' for interacting with sysmgr. This tool can be used to check
the status and start/stop/restart services.

When sysmgr picks up a service script inside the service directory, it
automatically starts the service unless stopped.


Details of implementation
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The initial implementation of sysmgr was written in POSIX shell, and it used
POSIX compliant base-tools, however, in order to spawn as little processes as
possible, it did some Linuxisms which prevented portability. The current
implementation is written in C99, and it only uses functions from the POSIX-2008
C Library, so it should work on all POSIX-compatible systems. Testing required.


Building and installing
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Before building sysmgr, it is best to take a look at the config.h and config.mk
files, and modify them to fit your system. Afterwards you can do the following
(as root if necessary):

    make
    make install


You can then install service scripts to your service directory and run sysmgr.


Service scripts
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Service scripts can be any executable ranging from shell scripts to C binaries.
The only requirement is that they can be executable. An example script is as
follows:

    #!/bin/sh -e
    exec httpd -f -p 8080 -h /var/pub/www


The exec call in the shell script makes sure that sysmgr is tracking the process
id of the httpd program rather than the shell script. It isn't necessary, but it
is the best practice to do so.

On certain occasions a service can depend on other services to be able to start.
That's why a sysmgr-depends tool is supplied, in order to make sure a service
can wait until another service is up.

    #!/bin/sh -e
    sysmgr-depends dbus
    exec NetworkManager -n


More information
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More usage information can be found on the following manual pages:

- runsyssv(1)
- svctl(1)
- sysmgr(8)
- sysmgr-depends(1)