[php-fpm] new check, get perf insight of your php-fpm install

[LeoCavaille]

Changelog:

Add first version of check by @arosenhagen

This check targets an install of php-fpm, through the webserver
we query the status and ping paths of FPM, and we transform the
output of these commands in metrics and service checks.

[leo@datadoghq.com] Rebased, fixing up commits together and solved
conflicts.

Revamp the PHP FPM integration

• Consolidated in one check ping + status queries
• Removed a lot of unused vars, simplified functions, make it look
  prettier
• Set up integration testing on Travis by:
  • installing a fresh nginx as a fast CGI passthru
  • installing a PHP version from source which ships the php-fpm
    binary
  • making them play together accepting connections to the
    /status and /ping paths

Supersedes #630
Please review @LotharSee @remh

[LotharSee]

A few suggestions about these names:

• Group some of them (processes.active, processes.total, processes.max_active, ...)
• Make some of them more clear (what are listen_queue and listen_queue_len? Again, group them listen_queue.something)
• We could call prefix that fpm. instead of php_fpm
• Use service check names close to what we already have. (is_connect is common but maybe not relevant in the case, is_running sounds better and that's what we have with Gunicorn)

[LeoCavaille]

• good idea
• will try that, after re-reading the doc
• I am not sure about this one, the integration is named PHP-FPM, I feel like we should try to keep some consistency in names, or change everything from php_fpm to fpm then but I find it confusing (other stuff is called fpm too...)
• I think you meant can_connect, in this case
  • can_connect is correct in a way, but it's an understatement, because we got a pong from php fpm, meaning the server is ready to process requests
  • is_running sound a little bit like a process check to me
  • it's closer to an "haproxy-like" status heartbeat (people actually use it for that), I am open to suggestions, what do you think?

[LotharSee]

The service check name is a good question: the closest integration that we have is Gunicorn, but I am not a big fan of is_running.
It was just to raise this question and see if we can find something consistent. But since this is very specific, it's better preferring something with more sense. can_ping?

[jippi]

👍

[arosenhagen]

thx for taking this over. Happy to see that this will go forward and eventually be a part of an upcoming release.

[LeoCavaille]

@LotharSee fixed your comments. Let me know if the new names are OK and I'll merge it.

[LotharSee]

Extra comments on the names.

First, since I didn't get what the listen_queue is, I had to look at the doc. This one is pretty good
http://centminmod.com/phpfpm.html#browserstatus

• Try to keep the same depth per "group". For example php_fpm.processes.active.max and php_fpm.processes. max_reached should have the same number of dots.
• Also, finishing by .max could be confusing (with histograms) php_fpm.listen_queue_reqs and php_fpm.listen_queue_reqs.max (they also don't have the same depth). Could use max_ instead.
• Not sure what we want to do with "max listen queue", "max active processes" and "max children reached" since they are counters initialized at PHP-FPM startup. Exception with "max children reached": it could be a counter.

[jippi]

Yes! I was working on this myself, when is this released to the official deb dd-agent version ? :)

[remh]

Hi @jippi . This will go out with our 5.3.0 release, which should be in around 3 weeks!

[remh]

In the same time if you want to beta test it, you can just download from github the php-fpm.py file into your /etc/dd-agent/checks.d directory and the yaml file in your /etc/dd-agent/conf.d directory

[jippi]

@remh shine, going to do just that then :)

Thanks

[coveralls]

Changes Unknown when pulling a23c7fb on leo/php_check into * on master*.