[[configuration-autodiscover]]
== Autodiscover

When you run applications on containers, they become moving targets to the monitoring system. Autodiscover
allows you to track them and adapt settings as changes happen. By defining configuration templates, the
autodiscover subsystem can monitor services as they start running.

You define autodiscover settings in the  +{beatname_lc}.autodiscover+ section of the +{beatname_lc}.yml+
config file. To enable autodiscover, you specify a list of providers.

[float]
=== Providers

Autodiscover providers work by watching for events on the system and translating those events into internal autodiscover
events with a common format. When you configure the provider, you can use fields from the autodiscover event to set
conditions that, when met, launch specific configurations.

On start, {beatname_uc} will scan existing containers and launch the proper configs for them. Then it will watch for new
start/stop events. This ensures you don't need to worry about state, but only define your desired configs.

[float]
===== Docker

The Docker autodiscover provider watches for Docker containers to start and stop. These are the available fields on every
event:

  * host
  * port
  * docker.container.id
  * docker.container.image
  * docker.container.name
  * docker.container.labels


For example:

[source,yaml]
-------------------------------------------------------------------------------------
{
  "host": "10.4.15.9",
  "port": 6379,
  "docker": {
    "container": {
      "id": "382184ecdb385cfd5d1f1a65f78911054c8511ae009635300ac28b4fc357ce51"
      "name": "redis",
      "image": "redis:3.2.11",
      "labels": {
        "io.kubernetes.pod.namespace": "default"
        ...
      }
    }
  }
}
-------------------------------------------------------------------------------------

You can define a set of configuration templates to be applied when the condition matches an event. Templates define
a condition to match on autodiscover events, together with the list of configurations to launch when this condition
happens.

Conditions match events from the provider. Providers use the same format for <<conditions>> that
processors use.

Configuration templates can contain variables from the autodiscover event. They can be accessed under the `data` namespace.
For example, with the example event, "`${data.port}`" resolves to `6379`.

include::../../{beatname_lc}/docs/autodiscover-docker-config.asciidoc[]


ifeval::["{beatname_lc}"=="filebeat"]
[WARNING]
=======================================
When using autodiscover, you have to be careful when defining config templates, especially if they are
reading from places holding information for several containers. For instance, under this file structure:

`/mnt/logs/<container_id>/*.log`

You can define a config template like this:

**Wrong settings**:

[source,yaml]
-------------------------------------------------------------------------------------
autodiscover.providers:
  - type: docker
    templates:
      - condition.contains:
          docker.container.image: nginx
        config:
          - type: log
            paths:
              - "/mnt/logs/*/*.log"
-------------------------------------------------------------------------------------

That would read all the files under the given path several times (one per nginx container). What you really
want is to scope your template to the container that matched the autodiscover condition. Good settings:

[source,yaml]
-------------------------------------------------------------------------------------
autodiscover.providers:
  - type: docker
    templates:
      - condition.contains:
          docker.container.image: nginx
        config:
          - type: log
            paths:
              - "/mnt/logs/${data.docker.container.id}/*.log"
-------------------------------------------------------------------------------------

=======================================
endif::[]

[float]
===== Kubernetes

The Kubernetes autodiscover provider watches for Kubernetes pods to start, update, and stop. These are the available fields on every
event:

  * host
  * port (if exposed)
  * kubernetes.container.id
  * kubernetes.container.image
  * kubernetes.container.name
  * kubernetes.labels
  * kubernetes.namespace
  * kubernetes.node.name
  * kubernetes.pod.name

If the `include_annotations` config is added to the provider config, then the list of annotations present in the config
are added to the event.

For example:

[source,yaml]
-------------------------------------------------------------------------------------
{
  "host": "172.17.0.21",
  "port": 9090,
  "kubernetes": {
    "container": {
      "id": "bb3a50625c01b16a88aa224779c39262a9ad14264c3034669a50cd9a90af1527",
      "image": "prom/prometheus",
      "name": "prometheus"
    },
    "labels": {
      "project": "prometheus",
      ...
    },
    "namespace": "default",
    "node": {
      "name": "minikube"
    },
    "pod": {
      "name": "prometheus-2657348378-k1pnh"
    }
  },
}
-------------------------------------------------------------------------------------

The configuration of templates and conditions is similar to that of the Docker provider. Configuration templates can
contain variables from the autodiscover event. They can be accessed under data namespace.

The `kubernetes` autodiscover provider has the following configuration settings:

`in_cluster`:: (Optional) Use in cluster settings for Kubernetes client, `true`
  by default.
`host`:: (Optional) Identify the node where {beatname_lc} is running in case it
  cannot be accurately detected, as when running {beatname_lc} in host network
  mode.
`kube_config`:: (Optional) Use given config file as configuration for Kubernetes
  client.

include::../../{beatname_lc}/docs/autodiscover-kubernetes-config.asciidoc[]

[float]
===== Manually Defining Ports with Kubernetes

Declare exposed ports in your pod spec if possible. Otherwise, you will need to use
multiple templates with complex filtering rules. The {port} variable will not be
present, and you will need to hardcode ports. Example: `{data.host}:1234`

When ports are not declared, Autodiscover generates a config using your provided
template once per pod, and once per container. These generated configs are
de-duplicated after they are generated. If the generated configs for multiple
containers are identical, they will be merged into one config.

Pods share an identical host. If only the `{data.host}` variable is interpolated,
then one config will be generated per host. The configs will be identical.
After they are de-duplicated, only one will be used.

ifdef::autodiscoverJolokia[]
[float]
===== Jolokia (experimental)

The Jolokia autodiscover provider uses Jolokia Discovery to find agents running
in your host or your network.

Jolokia Discovery mechanism is supported by any Jolokia agent since version
1.2.0, it is enabled by default when Jolokia is included in the application as
a JVM agent, but disabled in other cases as the OSGI or WAR (Java EE) agents.
In any case, this feature is controlled with two properties:

  * `discoveryEnabled`, to enable the feature
  * `discoveryAgentUrl`, if set, this is the URL announced by the agent when
    being discovered, setting this parameter implicitly enables the feature

There are multiple ways of setting these properties, and they can vary from
application to application, please refer to the documentation of your
application to find the more suitable way to set them in your case.
 
Jolokia Discovery is based on UDP multicast requests. Agents join the multicast
group 239.192.48.84, port 24884, and discovery is done by sending queries to
this group. You have to take into account that UDP traffic between Metricbeat
and the Jolokia agents has to be allowed. Also notice that this multicast
address is in the 239.0.0.0/8 range, that is reserved for private use within an
organization, so it can only be used in private networks.

These are the available fields on every event:

  * jolokia.agent.id
  * jolokia.agent.version
  * jolokia.secured
  * jolokia.server.product
  * jolokia.server.vendor
  * jolokia.server.version
  * jolokia.url

The configuration of this provider consists in a set of network interfaces, as
well as a set of templates as in other providers. The network interfaces will be
the ones used for discovery probes, they have these settings:

`name`:: the name of the interface (e.g. `br0`), it can contain a wildcard
  as suffix to apply the same settings to multiple network interfaces of
  the same type (e.g. `br*`).
`interval`:: time between probes (defaults to 10s)
 `grace_period`:: time since the last reply to consider an instance stopped
  (defaults to 30s)
`probe_timeout`:: max time to wait for responses since a probe is sent
  (defaults to 1s)

include::../../{beatname_lc}/docs/autodiscover-jolokia-config.asciidoc[]
endif::autodiscoverJolokia[]

ifdef::autodiscoverHints[]
[[configuration-autodiscover-hints]]
=== Hints based autodiscover

include::../../{beatname_lc}/docs/autodiscover-hints.asciidoc[]
endif::autodiscoverHints[]

[[configuration-autodiscover-advanced]]
=== Advanced usage

////
Builders are not exposed in docs, as we only have `hints` builder by the moment,
and that's covered in previous section

[float]
==== Builders
Builders allow users to pass hints to autodiscover for it to be able to make decisions
on how and what kind of configuration should be generated. Each Beat can define its own
Builders that it can use. Hints are generated based on all information that is passed to
the provider using a prefix "co.elastic.*". The Kubernetes provider uses annotations and
the Docker provider uses labels to achieve the same.

////

[float]
==== Appenders
Appenders allow users to append configuration that is already built with the help of either templates
or builders. Appenders can be configured to be applied only when a required condition is matched. The kind
of configuration that is applied is specific to each appender.

[float]
===== Config
The config appender can apply a config on top of the config that was generated by
templates or builders. The config is applied whenever a provided condition is matched. It is always
applied if there is no condition provided.

["source","yaml",subs="attributes"]
-------------------------------------------------------------------------------------
metricbeat.autodiscover:
  providers:
    - type: kubernetes
      templates:
        ...
      appenders:
        - type: config
          condition.equals:
            kubernetes.namespace: "prometheus"
          config:
            fields:
              type: monitoring
-------------------------------------------------------------------------------------