Files
patroni/features/watchdog.feature
T
Ants AasmaandAlexander Kukushkin 70d718a058 Simplify watchdog code (#452)
* Only activate watchdog while master and not paused

We don't really need the protections while we are not master. This way
we only need to tickle the watchdog when we are updating leader key or
while demotion is happening.

As implemented we might fail to notice to shut down the watchdog if
someone demotes postgres and removes leader key behind Patroni's back.
There are probably other similar cases. Basically if the administrator
if being actively stupid they might get unexpected restarts. That seems
fine.

* Add configuration change support. Change MODE_REQUIRED to disable leader eligibility instead of closing Patroni.

Changes watchdog timeout during the next keepalive when ttl is changed. Watchdog driver and requirement can also be switched online.

When watchdog mode is `required` and watchdog setup does not work then the effect is similar to nofailover. Add watchdog_failed to status API to signify this. This is True only when watchdog does not work **AND** it is required.

* Reset implementation when config changed while active.

* Add watchdog safety margin configuration

Defaults to 5 seconds. Basically this is the maximum amount of time
that can pass between the calls to odcs.update_leader()` and
`watchdog.keepalive()`, which are called right after each other. Should
be safe for pretty much any sane scenario and allows the default
settings to not trigger watchdog when DCS is not responding.

* Cancel bootstrap if watchdog activation fails

The system would have demoted itself anyway the next HA loop. Doing it
in bootstrap gives at least some other node chance to try bootstrapping
in the hope that it is configured correctly.

If all nodes are unable to activate they will continue to try until the
disk is filled with moved datadirs. Perhaps not ideal behavior, but as
the situation is unlikely to resolve itself without administrator
intervention it doesn't seem too bad.
2017-07-27 12:16:11 +02:00

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Gherkin

Feature: watchdog
Verify that watchdog gets pinged and triggered under appropriate circumstances.
Scenario: watchdog is opened, pinged and closed
Given I start postgres0 with watchdog
Then postgres0 is a leader after 10 seconds
And postgres0 role is the primary after 10 seconds
And postgres0 watchdog has been pinged after 10 seconds
When I shut down postgres0
Then postgres0 watchdog has been closed
#TODO: test watchdog is disabled during pause
#TODO: test watchdog is disabled properly when shutting down
Scenario: watchdog is triggered if patroni stops responding
Given I start postgres0 with watchdog
Then postgres0 role is the primary after 10 seconds
When postgres0 hangs for 30 seconds
Then postgres0 watchdog is triggered after 30 seconds