Allow connection_timeout to be set for MySQL checks
#2729
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Defaults to the original 'None' behaviour: falling back to OS socket defaults on sock.settimeout()
| @@ -330,9 +330,10 @@ def _get_config(self, instance): | |||
| options = instance.get('options', {}) | |||
| queries = instance.get('queries', []) | |||
| ssl = instance.get('ssl', {}) | |||
| connect_timeout = instance.get('connect_timeout', None) | |||
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Should connect_timeout be cast as an int ?
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If this is a question of what the default setting should be:
- Setting it to
Nonepreserves the original check behaviour (leaving it to system socket defaults). - Explicitly setting it to
1 secondchanges the current behaviour, and I'm not sure that assuming 1 second would be appropriate for everyone.
The actual code that changes the socket timeout accepts any value types integer/float as well as None.
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I was wondering if we had to cast the instance.get('connect_timeout') to an int when it wasn't None, but it doesn't seem to be needed.
We have to keep the default to None for backward compatibility, even if it would probably better to set one at 5 seconds or so. Thanks for the details!
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Thank you for the PR @scottgeary ! I added one comment, and I was also wondering why you didn't add the |
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Thanks again for the PR, it's merged now and will be part of the next minor release! |
* Allow connection_timeout to be set for pymysql instances Defaults to the original 'None' behaviour: falling back to OS socket defaults on sock.settimeout() * Pass in connect_timeout when using default file too
What does this PR do?
Allow a connection timeout to be used on when connecting to MySQL instances.
Motivation
When monitoring more than one instance of MySQL, if the host becomes unavailable, it'll block all the other MySQL instance checks. This block can be longer than the polling period, and you get false alerts and service checks.
Use case: Monitoring many RDS instances from a single host. A failover event occurs, causing connection issues to a single box temporarily. This connection hang (while the Master is being rotated), also blocks all the other monitored instances.
Testing Guidelines
Unsure how to a reasonable test case. Other than pull a remote host down, or disable networking.
Additional Notes
Defaults to the original no-timeout 'None' behaviour. When the original behaviour is used, the OS socket defaults on sock.settimeout() are used. Which could be a long time.
Also,
read_timeout+write_timeoutcould also occur (once connected, and issuing SQL), but the bundled version ofpymysql(v0.6.6) isn't new enough to contain these parameters. (v0.7.3 required).