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Improve doc for node_is_replica

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node_is_replica is using the following Patroni endpoints: replica, asynchronous
and synchronous. The first two implement the lag tag. For these endpoints
the state of a replica node doesn't reflect the replication state
(streaming or in archive recovery), we only know if it's running. The
timeline is also not checked.

Therefore, if a cluster is using asynchronous replication, it is recommended
to check for the lag to detect a divegence as soon as possible.
This commit is contained in:
benoit 2024-02-26 14:16:47 +01:00 committed by Benoit
parent 364a385a2f
commit a4ed20210c
3 changed files with 26 additions and 6 deletions
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1
CHANGELOG.md
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@ -24,6 +24,7 @@
### Misc
* Improve the documentation for node_is_replica.
* Improve test coverage by running an HTTP server to fake the Patroni API (#55
by @dlax).
* Work around old pytest versions in type annotations in the test suite.

15
README.md
View file

@ -45,7 +45,7 @@ Commands:
node_is_leader Check if the node is a leader node.
node_is_pending_restart Check if the node is in pending restart...
node_is_primary Check if the node is the primary with the...
node_is_replica Check if the node is a running replica...
node_is_replica Check if the node is a replica with no...
node_patroni_version Check if the version is equal to the input
node_tl_has_changed Check if the timeline has changed.
```
@ -437,12 +437,21 @@ Options:
```
Usage: check_patroni node_is_replica [OPTIONS]
Check if the node is a running replica with no noloadbalance tag.
Check if the node is a replica with no noloadbalance tag.
It is possible to check if the node is synchronous or asynchronous. If
nothing is specified any kind of replica is accepted. When checking for a
nothing is specified any kind of replica is accepted. When checking for a
synchronous replica, it's not possible to specify a lag.
This service is using the following Patroni endpoints: replica, asynchronous
and synchronous. The first two implement the `lag` tag. For these endpoints
the state of a replica node doesn't reflect the replication state
(`streaming` or `in archive recovery`), we only know if it's `running`. The
timeline is also not checked.
Therefore, if a cluster is using asynchronous replication, it is recommended
to check for the lag to detect a divegence as soon as possible.
Check:
* `OK`: if the node is a running replica with noloadbalance tag and the lag is under the maximum threshold.
* `CRITICAL`: otherwise

16
check_patroni/cli.py
View file

@ -621,10 +621,20 @@ def node_is_leader(ctx: click.Context, check_standby_leader: bool) -> None:
def node_is_replica(
ctx: click.Context, max_lag: str, check_is_sync: bool, check_is_async: bool
) -> None:
"""Check if the node is a running replica with no noloadbalance tag.
"""Check if the node is a replica with no noloadbalance tag.
It is possible to check if the node is synchronous or asynchronous. If nothing is specified any kind of replica is accepted.
When checking for a synchronous replica, it's not possible to specify a lag.
It is possible to check if the node is synchronous or asynchronous. If
nothing is specified any kind of replica is accepted. When checking for a
synchronous replica, it's not possible to specify a lag.
This service is using the following Patroni endpoints: replica, asynchronous
and synchronous. The first two implement the `lag` tag. For these endpoints
the state of a replica node doesn't reflect the replication state
(`streaming` or `in archive recovery`), we only know if it's `running`. The
timeline is also not checked.
Therefore, if a cluster is using asynchronous replication, it is
recommended to check for the lag to detect a divegence as soon as possible.
\b
Check: