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 heartbeat.autodiscover section of the heartbeat.yml config file. To enable autodiscover, you specify a list of 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 optionally use fields from the autodiscover event to set conditions that, when met, launch specific configurations.

On start, Heartbeat 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.

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

For example:

{
  "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.

Heartbeat supports templates for modules:

heartbeat.autodiscover:
  providers:
    - type: docker
      templates:
        - condition:
            contains:
              docker.container.image: redis
          config:
            - type: tcp
              hosts: ["${data.host}:${data.port}"]
              schedule: "@every 1s"
              timeout: 1s

This configuration launches a redis monitor for all containers running an image with redis in the name.

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

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.

If the include_labels config is added to the provider config, then the list of labels present in the config will be added to the event.

If the exclude_labels config is added to the provider config, then the list of labels present in the config will be excluded from the event.

if the labels.dedot config is set to be true in the provider config, then . in labels will be replaced with _.

if the annotations.dedot config is set to be true in the provider config, then . in annotations will be replaced with _.

For example:

{
  "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:

Heartbeat supports templates for modules:

heartbeat.autodiscover:
  providers:
    - type: kubernetes
      include_annotations: ["prometheus.io.scrape"]
      templates:
        - condition:
            contains:
              kubernetes.annotations.prometheus.io.scrape: "true"
          config:
            - type: http
              hosts: ["${data.host}:${data.port}"]
              schedule: "@every 1s"
              timeout: 1s

This configuration launches an http module for all containers of pods annotated with prometheus.io.scrape=true.

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.