Run instance reaper

[bbangert]

AWSPool's reaper method currently doesn't properly terminate idle (> 1 hour) instances based on their time. It should determine if an instance hasn't been used for an hour, and terminate it if its idle too long.

The reap method should also be automatically run every minute or so to check, so it will need to be scheduled on startup into the event loop.

[tarekziade]

How do we want to determine that an instance has been idling for too long ? Sounds like we want to detect an instance that's not really producing any tests results anymore.

One option would be to parse the logs produced by the tests, to see if the box is still producing something. Another empirical option is to connect to that box and to see if somethings happening in it.

I am not 100% sure what's the best option. I think 2

@rpappalax do you know what's the usual behavior when a slave box gets stuck ?

[tarekziade]

I think I have a better idea: we could self-terminate the instance with a script that runs in it

see http://stackoverflow.com/questions/10541363/self-terminating-aws-ec2-instance

The script would periodically check if the docker container is busy, if not start a coutdown before terminating the instance.

[rpappalax]

@tarekziade Yea, I think this is a great idea. I wonder if we could also automatically spin up a fresh node if one is lost due to self-termination.

[rpappalax]

Also, in regards to the attack nodes idling to long, I'm not sure how / if these are related but I know that @pjenvey is also investigating:
[1]. Issue #44: Loads-broker stalls with message: No instances running, collection done
[2]. connection timeout w/ the following message:

[2016-10-04 00:24:09,993][19217] Got exception: HTTPConnectionPool(host='54.162.133.99', port=2375): Max retries exceeded with url: /v1.21/containers/json?trunc_cmd=0&size=0&all=0&limit=-1 (Caused by ConnectTimeoutError(<requests.packages.urllib3.connection.HTTPConnection object at 0x7f10e17b9e80>, 'Connection to 54.162.133.99 timed out. (connect timeout=5)'))

[tarekziade]

I wonder if we could also automatically spin up a fresh node if one is lost due to self-termination.

If the broker is doing correctly its job, it should do it once it detected the node was terminated. I don't know if this is happening live during a test though. I doubt it.

[tarekziade]

Here's the approach: https://github.com/loads/awskiller/blob/master/awskiller/killer.py

That could be deployed on the CoreOS alongside docker, and monitor the docker process.
If the docker process is idling for an hour, given a threshold, the script can trigger termination.

Another possibility is to have the script send to statsd the docker mean cpu usage/hour, that would let the broker get the info and decide wether t reap it or not.

I think this loose approach avoids any extra work between the nodes and the broken to reap idling instances.

[bbangert]

I really like this approach, it should probably check once every 5 mins, and if it goes for a whole hour without being used, then terminate itself.

The only problem I see is that it means the loads-broker will have to refresh node data more frequently from AWS to ensure it doesn't try to use a node that has removed itself from the pool.

[tarekziade]

the loads-broker will have to refresh node data more frequently from AWS

I guess we can look at the hot spots. In theory, checking on node health should be doable asynchronously in the event loop, and even with hundreds of nodes I suspect that should not be impossible to optimize.

I propose we try that.

[bbangert]

@pjenvey points out that its alive status can already be queried directly via docker, so we shouldn't worry about that.

[tarekziade]

I've finished a first version of "awskiller" a small command that will run a system command

https://github.com/loads/awskiller

$ .tox/py35/bin/awskiller --help
usage: awskiller [-h] [--pid PID] [--name NAME] [--killer KILLER]
                 [--threshold THRESHOLD] [--duration DURATION]
                 [--interval INTERVAL] [--verbose]

AWS Killer

optional arguments:
  -h, --help            show this help message and exit
  --pid PID             Process PID
  --name NAME           Process Name
  --killer KILLER       Command to run
  --threshold THRESHOLD
                        CPU Threshold
  --duration DURATION   Watch Duration
  --interval INTERVAL   Watch Interval
  --verbose             Display more info

$ .tox/py35/bin/awskiller --name firefox --verbose
Watching firefox 13%  ^C

Will now see how to hook it in CoreOS so it runs alongside docker and watch it