[libbeat] AWS ELB Monitoring (#12401) (#13105)

Experimental autodiscovery provider for AWS ELBs.

(cherry picked from commit 2c85c97)

heartbeat/docs/autodiscover-aws-elb-config.asciidoc

@@ -0,0 +1,27 @@
+{beatname_uc} supports templates for modules:
+
+["source","yaml",subs="attributes"]
+-------------------------------------------------------------------------------------
+heartbeat.autodiscover:
+  providers:
+  - type: aws_elb
+    period: 1m
+    regions: ["us-east-1", "us-east-2"]
+    # If you don't wish to use env vars or shared credentials files explicitly put credentials here.
+    #access_key_id: my-access-key
+    #secret_access_key: my-secret-access-key
+    #session_token: my-session-token
+    templates:
+    - condition:
+        equals.port: 8080
+      config:
+      - type: tcp
+        hosts: ["${data.host}:${data.port}"]
+        schedule: "@every 5s"
+        timeout: 1s
+-------------------------------------------------------------------------------------
+
+This configuration launches a `tcp` monitor for all ELBs that have a declared port.
+
+This autodiscover provider takes our standard AWS credentials options.
+

heartbeat/docs/configuring-howto.asciidoc

@@ -75,7 +75,9 @@ include::{libbeat-dir}/docs/loggingconfig.asciidoc[]
 include::{libbeat-dir}/docs/shared-env-vars.asciidoc[]
 :standalone!:
 
+:autodiscoverAWSELB:
 include::{libbeat-dir}/docs/shared-autodiscover.asciidoc[]
+:autodiscoverAWSELB!:
 
 :standalone:
 include::{libbeat-dir}/docs/yaml.asciidoc[]

libbeat/docs/shared-autodiscover.asciidoc

@@ -21,7 +21,10 @@ start/stop events. This ensures you don't need to worry about state, but only de
 [float]
 ===== Docker
 
-The Docker autodiscover provider watches for Docker containers to start and stop. These are the available fields on every
+The Docker autodiscover provider watches for Docker containers to start and stop.
+
+
+These are the available fields during within config templating. The `docker.*` fields will be available on each emitted event.
 event:
 
   * host
@@ -113,8 +116,9 @@ endif::[]
 [float]
 ===== Kubernetes
 
-The Kubernetes autodiscover provider watches for Kubernetes pods to start, update, and stop. These are the available fields on every
-event:
+The Kubernetes autodiscover provider watches for Kubernetes pods to start, update, and stop.
+
+These are the available fields during within config templating. The `kubernetes.*` fields will be available on each emitted event.
 
   * host
   * port (if exposed)
@@ -231,7 +235,7 @@ 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:
+These are the available fields during within config templating. The `jolokia.*` fields will be available on each emitted event.
 
   * jolokia.agent.id
   * jolokia.agent.version
@@ -257,6 +261,43 @@ the ones used for discovery probes, they have these settings:
 include::../../{beatname_lc}/docs/autodiscover-jolokia-config.asciidoc[]
 endif::autodiscoverJolokia[]
 
+ifdef::autodiscoverAWSELB[]
+[float]
+===== Amazon ELBs
+
+*Note: This provider is experimental*
+
+The Amazon ELB autodiscover provider discovers https://aws.amazon.com/elasticloadbalancing/[ELBs] and their listeners. This is useful when you don't want to connect
+directly to a service, but rather to the ELB fronting a pool of services.
+
+This provider will yield one config block per ELB Listener. So, if you have one ELB exposing both ports 80 and 443, it
+will generate two configs, one for each port. Keep in mind that the beat will de-duplicate configs. So, if the generated
+configs are the same only one will actually run.
+
+This provider will load AWS credentials using the standard AWS environment variables and shared credentials files see https://docs.aws.amazon.com/general/latest/gr/aws-access-keys-best-practices.html[Best Practices for Managing AWS Access Keys] for more information. If you do not wish to use these, you may explicitly set the `access_key_id` and `secret_access_key` variables.
+
+These are the available fields during within config templating. The `elb_listener.*` fields will be available on each emitted event.
+
+  * host
+  * port
+  * elb_listener.listener_arn
+  * elb_listener.load_balancer_arn
+  * elb_listener.protocol
+  * elb_listener.type
+  * elb_listener.scheme
+  * elb_listener.availability_zones
+  * elb_listener.created
+  * elb_listener.state
+  * elb_listener.ip_address_type
+  * elb_listener.security_groups
+  * elb_listener.vpc_id
+  * elb_listener.ssl_policy
+
+include::../../{beatname_lc}/docs/autodiscover-aws-elb-config.asciidoc[]
+
+endif::autodiscoverAWSELB[]
+
+
 ifdef::autodiscoverHints[]
 [[configuration-autodiscover-hints]]
 === Hints based autodiscover