Rippler
Monitoring for cron jobs — know when a job stops running.
Rippler watches jobs that are supposed to run on a schedule. Your job calls a URL when it runs; if that call does not arrive when expected, you get told.
Two ways in
Command line
Point the CLI at your crontab and it wires everything up for you.
HTTP API
Create and read monitors from your own tooling.
The idea
A monitor expects a ping on a schedule. Three things can happen:
- The ping arrives on time. The monitor stays up, and nothing happens.
- The ping is late. The monitor enters its grace period. Still nothing happens — grace exists to absorb the normal jitter in when a job finishes.
- Grace runs out, or the job reports a failure. The monitor goes down, and once it has failed as many times in a row as you allow, an alert goes out.
That last part is worth knowing about before you are woken at 3am: a job that fails occasionally and fixes itself on the next run does not have to alert. See failure tolerance.