The local
exporter is the default exporter in X-Pack monitoring. It routes data
back into the same (local) cluster. In other words, it uses the production
cluster as the monitoring cluster. For example:
This exporter exists to provide a convenient option when hardware is simply not available. It is also a way for developers to get an idea of what their actions do for pre-production clusters when they do not have the time or resources to provide a separate monitoring cluster. However, this exporter has disadvantages that impact the local cluster:
For the local
exporter, all setup occurs only on the elected master node. This
means that if you do not see any monitoring templates or ingest pipelines, the
elected master node is having issues or it is not configured in the same way.
Unlike the http
exporter, the local
exporter has the advantage of accessing
the monitoring cluster’s up-to-date cluster state. It can therefore always check
that the templates and ingest pipelines exist without a performance penalty. If
the elected master node encounters errors while trying to create the monitoring
resources, it logs errors, ignores that collection, and tries again after the
next collection.
The elected master node is the only node to set up resources for the local
exporter. Therefore all other nodes wait for the resources to be set up before
indexing any monitoring data from their own collectors. Each of these nodes logs
a message indicating that they are waiting for the resources to be set up.
One benefit of the local
exporter is that it lives within the cluster and
therefore no extra configuration is required when the cluster is secured with
Elastic Stack security features. All operations, including indexing operations, that
occur from a local
exporter make use of the internal transport mechanisms
within Elasticsearch. This behavior enables the exporter to be used without providing any
user credentials when security features are enabled.
For more information about the configuration options for the local
exporter,
see Local Exporter Settings.
One feature of the local
exporter, which is not present in the http
exporter,
is a cleaner service. The cleaner service runs once per day at 01:00 AM UTC on
the elected master node.
The role of the cleaner service is to clean, or curate, the monitoring indices
that are older than a configurable amount of time (the default is 7d
). This
cleaner exists as part of the local
exporter as a safety mechanism. The http
exporter does not make use of it because it could enable a single misconfigured
node to prematurely curate data from other production clusters that share the
same monitoring cluster.
In a dedicated monitoring cluster, the cleaning service can be used without having to also monitor the monitoring cluster. For example: