The purpose of exporters is to take data collected from any Elastic Stack source and route it to the monitoring cluster. It is possible to configure more than one exporter, but the general and default setup is to use a single exporter.
There are two types of exporters in Elasticsearch:
- The default exporter used by X-Pack monitoring for Elasticsearch. This exporter routes data back into the same cluster. See Local exporters.
- The preferred exporter, which you can use to route data into any supported Elasticsearch cluster accessible via HTTP. Production environments should always use a separate monitoring cluster. See HTTP exporters.
Both exporters serve the same purpose: to set up the monitoring cluster and route monitoring data. However, they perform these tasks in very different ways. Even though things happen differently, both exporters are capable of sending all of the same data.
Exporters are configurable at both the node and cluster level. Cluster-wide
settings, which are updated with the
_cluster/settings API, take precedence over
settings in the
elasticsearch.yml file on each node. When you update an
exporter, it is completely replaced by the updated version of the exporter.
It is critical that all nodes share the same setup. Otherwise, monitoring data might be routed in different ways or to different places.
When the exporters route monitoring data into the monitoring cluster, they use
_bulk indexing for optimal performance. All monitoring data is forwarded in
bulk to all enabled exporters on the same node. From there, the exporters
serialize the monitoring data and send a bulk request to the monitoring cluster.
There is no queuing—in memory or persisted to disk—so any failure during the
export results in the loss of that batch of monitoring data. This design limits
the impact on Elasticsearch and the assumption is that the next pass will succeed.
Routing monitoring data involves indexing it into the appropriate monitoring
indices. Once the data is indexed, it exists in a monitoring index that, by
default, is named with a daily index pattern. For Elasticsearch monitoring data, this is
an index that matches
.monitoring-es-6-*. From there, the data lives inside
the monitoring cluster and must be curated or cleaned up as necessary. If you do
not curate the monitoring data, it eventually fills up the nodes and the cluster
might fail due to lack of disk space.
There is also a disk watermark (known as the flood stage watermark), which protects clusters from running out of disk space. When this feature is triggered, it makes all indices (including monitoring indices) read-only until the issue is fixed and a user manually makes the index writeable again. While an active monitoring index is read-only, it will naturally fail to write (index) new data and will continuously log errors that indicate the write failure. For more information, see Disk-based Shard Allocation.
If a node or cluster does not explicitly define an X-Pack monitoring exporter, the following default exporter is used:
The exporter name uniquely defines the exporter, but it is otherwise unused.
When you specify your own exporters, you do not need to explicitly overwrite
If another exporter is already defined, the default exporter is not created. When you define a new exporter, if the default exporter exists, it is automatically removed.
Before exporters can route monitoring data, they must set up certain Elasticsearch resources. These resources include templates and ingest pipelines. The following table lists the templates that are required before an exporter can route monitoring data:
All cluster alerts for monitoring data.
All Beats monitoring data.
All Elasticsearch monitoring data.
All Kibana monitoring data.
All Logstash monitoring data.
The templates are ordinary Elasticsearch templates that control the default settings and mappings for the monitoring indices.
By default, monitoring indices are created daily (for example,
.monitoring-es-6-2017.08.26). You can change the default date suffix for
monitoring indices with the
index.name.time_format setting. You can use this
setting to control how frequently monitoring indices are created by a specific
http exporter. You cannot use this setting with
local exporters. For more
information, see HTTP Exporter Settings.
Some users create their own templates that match all index patterns,
which therefore impact the monitoring indices that get created. It is critical
that you do not disable
_source storage for the monitoring indices. If you do,
X-Pack monitoring for Kibana does not work and you cannot visualize monitoring data
for your cluster.
The following table lists the ingest pipelines that are required before an exporter can route monitoring data:
Upgrades X-Pack monitoring data coming from X-Pack 5.0 - 5.4 to be compatible with the format used in X-Pack monitoring 5.5.
A placeholder pipeline that is empty.
Exporters handle the setup of these resources before ever sending data. If resource setup fails (for example, due to security permissions), no data is sent and warnings are logged.
Empty pipelines are evaluated on the coordinating node during indexing and they are ignored without any extra effort. This inherently makes them a safe, no-op operation.
For monitoring clusters that have disabled
node.ingest on all nodes, it is
possible to disable the use of the ingest pipeline feature. However, doing so
blocks its purpose, which is to upgrade older monitoring data as our mappings
improve over time. Beginning in 6.0, the ingest pipeline feature is a
requirement on the monitoring cluster; you must have
node.ingest enabled on at
least one node.
Once any node running 5.5 or later has set up the templates and ingest
pipeline on a monitoring cluster, you must use Kibana 5.5 or later to view all
subsequent data on the monitoring cluster. The easiest way to determine
whether this update has occurred is by checking for the presence of indices
.monitoring-es-6-* (or more concretely the existence of the
new pipeline). Versions prior to 5.5 used
Each resource that is created by an X-Pack monitoring exporter has a
which is used to determine whether the resource should be replaced. The
field value represents the latest version of X-Pack monitoring that changed the
resource. If a resource is edited by someone or something external to
X-Pack monitoring, those changes are lost the next time an automatic update occurs.