Documentation Grafana Cloud Instrument and send data Grafana Alloy Reference Components discovery discovery.kubelet

discovery.kubelet

discovery.kubelet discovers Kubernetes pods running on the specified Kubelet and exposes them as scrape targets.

Usage

alloy Copy

discovery.kubelet "LABEL" {
}

Requirements

• The Kubelet must be reachable from the alloy pod network.
• Follow the Kubelet authorization documentation to configure authentication to the Kubelet API.

Arguments

The following arguments are supported:

The namespaces list limits the namespaces to discover resources in. If omitted, all namespaces are searched.

discovery.kubelet appends a /pods path to url to request the available pods. You can have additional paths in the url. For example, if url is https://kubernetes.default.svc.cluster.local:443/api/v1/nodes/cluster-node-1/proxy, then discovery.kubelet sends a request on https://kubernetes.default.svc.cluster.local:443/api/v1/nodes/cluster-node-1/proxy/pods

At most, one of the following can be provided:

• bearer_token argument.
• bearer_token_file argument.
• basic_auth block.
• authorization block.
• oauth2 block.

no_proxy can contain IPs, CIDR notations, and domain names. IP and domain names can contain port numbers. proxy_url must be configured if no_proxy is configured.

proxy_from_environment uses the environment variables HTTP_PROXY, HTTPS_PROXY and NO_PROXY (or the lowercase versions thereof). Requests use the proxy from the environment variable matching their scheme, unless excluded by NO_PROXY. proxy_url and no_proxy must not be configured if proxy_from_environment is configured.

proxy_connect_header should only be configured if proxy_url or proxy_from_environment are configured.

Blocks

The following blocks are supported inside the definition of discovery.kubelet:

The > symbol indicates deeper levels of nesting. For example, oauth2 > tls_config refers to a tls_config block defined inside an oauth2 block.

basic_auth block

password and password_file are mutually exclusive, and only one can be provided inside a basic_auth block.

authorization block

credential and credentials_file are mutually exclusive, and only one can be provided inside an authorization block.

oauth2 block

client_secret and client_secret_file are mutually exclusive, and only one can be provided inside an oauth2 block.

The oauth2 block may also contain a separate tls_config sub-block.

no_proxy can contain IPs, CIDR notations, and domain names. IP and domain names can contain port numbers. proxy_url must be configured if no_proxy is configured.

proxy_from_environment uses the environment variables HTTP_PROXY, HTTPS_PROXY and NO_PROXY (or the lowercase versions thereof). Requests use the proxy from the environment variable matching their scheme, unless excluded by NO_PROXY. proxy_url and no_proxy must not be configured if proxy_from_environment is configured.

proxy_connect_header should only be configured if proxy_url or proxy_from_environment are configured.

tls_config block

The following pairs of arguments are mutually exclusive and can’t both be set simultaneously:

• ca_pem and ca_file
• cert_pem and cert_file
• key_pem and key_file

When configuring client authentication, both the client certificate (using cert_pem or cert_file) and the client key (using key_pem or key_file) must be provided.

When min_version is not provided, the minimum acceptable TLS version is inherited from Go’s default minimum version, TLS 1.2. If min_version is provided, it must be set to one of the following strings:

• "TLS10" (TLS 1.0)
• "TLS11" (TLS 1.1)
• "TLS12" (TLS 1.2)
• "TLS13" (TLS 1.3)

Exported fields

The following fields are exported and can be referenced by other components:

Each target includes the following labels:

• __address__: The target address to scrape derived from the pod IP and container port.
• __meta_kubernetes_namespace: The namespace of the pod object.
• __meta_kubernetes_pod_name: The name of the pod object.
• __meta_kubernetes_pod_ip: The pod IP of the pod object.
• __meta_kubernetes_pod_label_<labelname>: Each label from the pod object.
• __meta_kubernetes_pod_labelpresent_<labelname>: true for each label from the pod object.
• __meta_kubernetes_pod_annotation_<annotationname>: Each annotation from the pod object.
• __meta_kubernetes_pod_annotationpresent_<annotationname>: true for each annotation from the pod object.
• __meta_kubernetes_pod_container_init: true if the container is an InitContainer.
• __meta_kubernetes_pod_container_name: Name of the container the target address points to.
• __meta_kubernetes_pod_container_id: ID of the container the target address points to. The ID is in the form <type>://<container_id>.
• __meta_kubernetes_pod_container_image: The image the container is using.
• __meta_kubernetes_pod_container_port_name: Name of the container port.
• __meta_kubernetes_pod_container_port_number: Number of the container port.
• __meta_kubernetes_pod_container_port_protocol: Protocol of the container port.
• __meta_kubernetes_pod_ready: Set to true or false for the pod’s ready state.
• __meta_kubernetes_pod_phase: Set to Pending, Running, Succeeded, Failed or Unknown in the lifecycle.
• __meta_kubernetes_pod_node_name: The name of the node the pod is scheduled onto.
• __meta_kubernetes_pod_host_ip: The current host IP of the pod object.
• __meta_kubernetes_pod_uid: The UID of the pod object.
• __meta_kubernetes_pod_controller_kind: Object kind of the pod controller.
• __meta_kubernetes_pod_controller_name: Name of the pod controller.

Component health

discovery.kubelet is reported as unhealthy when given an invalid configuration. In those cases, exported fields retain their last healthy values.

Debug information

discovery.kubelet does not expose any component-specific debug information.

Debug metrics

discovery.kubelet does not expose any component-specific debug metrics.

Examples

Bearer token file authentication

This example uses a bearer token file to authenticate to the Kubelet API:

alloy Copy

discovery.kubelet "k8s_pods" {
  bearer_token_file = "/var/run/secrets/kubernetes.io/serviceaccount/token"
}

prometheus.scrape "demo" {
  targets    = discovery.kubelet.k8s_pods.targets
  forward_to = [prometheus.remote_write.demo.receiver]
}

prometheus.remote_write "demo" {
  endpoint {
    url = PROMETHEUS_REMOTE_WRITE_URL

    basic_auth {
      username = USERNAME
      password = PASSWORD
    }
  }
}

Replace the following:

• PROMETHEUS_REMOTE_WRITE_URL: The URL of the Prometheus remote_write-compatible server to send metrics to.
• USERNAME: The username to use for authentication to the remote_write API.
• PASSWORD: The password to use for authentication to the remote_write API.

Limit searched namespaces

This example limits the namespaces where pods are discovered using the namespaces argument:

alloy Copy

discovery.kubelet "k8s_pods" {
  bearer_token_file = "/var/run/secrets/kubernetes.io/serviceaccount/token"
  namespaces = ["default", "kube-system"]
}

prometheus.scrape "demo" {
  targets    = discovery.kubelet.k8s_pods.targets
  forward_to = [prometheus.remote_write.demo.receiver]
}

prometheus.remote_write "demo" {
  endpoint {
    url = PROMETHEUS_REMOTE_WRITE_URL

    basic_auth {
      username = USERNAME
      password = PASSWORD
    }
  }
}

Replace the following:

• PROMETHEUS_REMOTE_WRITE_URL: The URL of the Prometheus remote_write-compatible server to send metrics to.
• USERNAME: The username to use for authentication to the remote_write API.
• PASSWORD: The password to use for authentication to the remote_write API.

Compatible components

discovery.kubelet has exports that can be consumed by the following components:

• Components that consume Targets