first-collector

A first collector

The smallest useful collector: one access, one value, one watch. Read it first.

How to read it

• The header, the first lines: need('protocol:ssh') asks for the SSH access of the host, set in the tree; output('users', 'number', …) declares the value returned; watch.above(…) proposes a watch, with its default thresholds. The master reads the header without running the code.
• The body, after the header: ssh.run runs the command on the host and returns output, errors and exit; value('users', …) returns the value declared under that name.
• text.trim takes the line break off the end of what the command printed.
• No threshold is written in the body: the poller judges the value by the watch, with the thresholds the administrator keeps or changes on the probe.

To adapt it

• Change the command, the name of the output and its label: any command that prints one number fits.
• Change the default thresholds of the watch, or its kind (watch.below, watch.state…): see the examples under examples/watches.