hacheck is a healthcheck-proxying service. It listens on port 3333, speaks HTTP, and has the following API:
This will check the following locations for service state:
- Depending on the value of
tcp: will attempt to connect to port
<query>is currently ignored
spool: will only check the spool state
mysql_passwordare set, will do a login and quit on the requested mysql port;
<query>is ignored and no logical database is selected.
When it does query the actual service check endpoint, hacheck MAY cache the value of that query for some amount of time
hacheck also comes with the command-line utilities
hastatus. These take a service name and manipulate the spool files, allowing you to pre-emptively mark a service as "up" or "down".
hacheck is written in Python and makes extensive use of the tornado asynchronous web framework (specifically, it uses the coroutine stuff in Tornado 3). Unit tests use nose and mock.
It runs on Python 2.6 and above, as well as Python 3.2 and above.
Imagine you want to take down the server
web01 for maintenance. Just SSH to it, then (as root) run
hadown all and wait however long your HAproxy healthchecking interval is. Do your maintenance, then run
haup all to put it back in service. So easy!
hacheck accepts a
-c flag which should point to a YAML-formatted configuration file. Some notable properties of this file:
cache_time: The duration for which check results may be cached
service_name_header: If set, the name of a header which will be populated with the service name on HTTP checks
log_path: Either the string
"stdout", the string
"stderr", or a fully-qualified path to a file to write logs to. Uses a WatchedFileHandler and ought to play nicely with logrotate
mysql_username: username to use when logging into mysql for checks
mysql_password: password to use when logging into mysql for checks
rlimit_nofile: set the NOFILE rlimit. If the string "max", will set the rlimit to the hard rlimit; otherwise, will be interpreted as an integer and set to that value.
hacheck exports some useful monitoring stuff at the
/status endpoint. It also exports a count of requests by source-IP and service name on the
If the mutornadomon package is available,
hacheck will import and use it, exposing standard stats about tornado to localhost at