ElasticSearch agent check should only query the local node. #1181
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Thanks a lot for the detailed feedback and the PR @jonaf ! We are going to review that. |
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Thanks a bunch @jonaf . We're merging it. |
remh
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Dec 18, 2014
ElasticSearch agent check should only query the local node.
olivielpeau
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Jun 4, 2015
The hostname matching is not needed anymore as: - since PR #1181 we only ask the _local node for stats when `is_external` is set to `false` - we don't match the hostname at all when `is_external` is `true` Matching hostnames can also filter out legitimate data when the local elasticsearch node reports a different hostname. See also issue #457
olivielpeau
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Jun 4, 2015
The hostname matching is not needed anymore as: - since PR #1181 we only ask the _local node for stats when `is_external` is set to `false` - we don't match the hostname at all when `is_external` is `true` Matching hostnames can also filter out legitimate data when the local elasticsearch node reports a different hostname. See also issue #457
olivielpeau
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Jun 5, 2015
The hostname matching is not needed anymore as: - since PR #1181 we only ask the _local node for stats when `is_external` is set to `false` - we don't match the hostname at all when `is_external` is `true` Matching hostnames can also filter out legitimate data when the local elasticsearch node reports a different hostname. See also issue #457
olivielpeau
added a commit
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Jun 9, 2015
The hostname matching is not needed anymore as: - since PR #1181 we only ask the _local node for stats when `is_external` is set to `false` - we don't match the hostname at all when `is_external` is `true` Matching hostnames can also filter out legitimate data when the local elasticsearch node reports a different hostname. See also issue #457
olivielpeau
added a commit
that referenced
this pull request
Jun 9, 2015
The hostname matching is not needed anymore as: - since PR #1181 we only ask the _local node for stats when `is_external` is set to `false` - we don't match the hostname at all when `is_external` is `true` Matching hostnames can also filter out legitimate data when the local elasticsearch node reports a different hostname. See also issue #457
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The current ElasticSearch agent check will cause all nodes in an ElasticSearch cluster to cease reporting metrics if one ElasticSearch node fails or is slow to respond to the request. This is because ElasticSearch will query all nodes in the cluster before providing a response. In practice, Bazaarvoice has seen this produce troubling side-effects in Datadog graphs: all the nodes in the cluster suddenly stop reporting metrics. This is particularly problematic when looking at historical data and trying to draw conclusions based on the data -- because the Datadog graphs draw a line between two visible data points, it is rarely obvious that no data was reported during a certain period of time; rather, it just looks like very unusual and sometimes frightening metrics were being sent from the ElasticSearch nodes.
The easy way to fix all of this is, of course, to simply inform ElasticSearch that it should only look at the local node stats, and allow all the other ElasticSearch nodes to do the same.
Tested with ElasticSearch 0.90.13 and later.