[role="xpack"]
[testenv="basic"]
[[local-exporter]]
=== Local Exporters

The `local` exporter is the default exporter in {monitoring}. It routes data 
back into the same (local) cluster. In other words, it uses the production 
cluster as the monitoring cluster. For example:
 
[source,yaml]
---------------------------------------------------
xpack.monitoring.exporters.my_local_exporter: <1>
  type: local
---------------------------------------------------
<1> The exporter name uniquely defines the exporter, but it is otherwise unused.

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:

* All indexing impacts the local cluster and the nodes that hold the monitoring 
indices' shards.
* Most collectors run on the elected master node. Therefore most indexing occurs 
with the elected master node as the coordinating node, which is a bad practice.
* Any usage of {monitoring} for {kib} uses the local cluster's resources for 
searches and aggregations, which means that they might not be available for
non-monitoring tasks.
* If the local cluster goes down, the monitoring cluster has inherently gone 
down with it (and vice versa), which generally defeats the purpose of monitoring.

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
{security}. All operations, including indexing operations, that occur from a 
`local` exporter make use of the internal transport mechanisms within {es}. This 
behavior enables the exporter to be used without providing any user credentials 
when {security} is enabled. 

For more information about the configuration options for the `local` exporter, 
see <<local-exporter-settings>>.

[[local-exporter-cleaner]]
==== Cleaner Service

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:

[source,yaml]
---------------------------------------------------
xpack.monitoring.collection.enabled: false <1>
xpack.monitoring.history.duration: 3d <2>
---------------------------------------------------
<1> Disable the collection of data on the monitoring cluster.
<2> Lower the default history duration from `7d` to `3d`. The minimum value is 
`1d`. This setting can be modified only when using a Gold or higher level 
license. For the Basic license level, it uses the default of 7 days.
