Reference

Components

discovery

discovery.kubernetes

General availability (GA)

`discovery.kubernetes`

discovery.kubernetes allows you to find scrape targets from Kubernetes resources. It watches cluster state, and ensures targets are continually synced with what’s currently running in your cluster.

If you supply no connection information, this component defaults to an in-cluster configuration. A kubeconfig file or manual connection settings can be used to override the defaults.

Usage

discovery.kubernetes "<LABEL>" {
  role = "<DISCOVERY_ROLE>"
}

Arguments

You can use the following arguments with discovery.kubernetes:

Name	Type	Description	Default	Required
`role`	`string`	Type of Kubernetes resource to query.		yes
`api_server`	`string`	URL of Kubernetes API server.		no
`bearer_token_file`	`string`	File containing a bearer token to authenticate with.		no
`bearer_token`	`secret`	Bearer token to authenticate with.		no
`enable_http2`	`bool`	Whether HTTP2 is supported for requests.	`true`	no
`follow_redirects`	`bool`	Whether redirects returned by the server should be followed.	`true`	no
`kubeconfig_file`	`string`	Path of kubeconfig file to use for connecting to Kubernetes.		no
`no_proxy`	`string`	Comma-separated list of IP addresses, CIDR notations, and domain names to exclude from proxying.		no
`proxy_connect_header`	`map(list(secret))`	Specifies headers to send to proxies during CONNECT requests.		no
`proxy_from_environment`	`bool`	Use the proxy URL indicated by environment variables.	`false`	no
`proxy_url`	`string`	HTTP proxy to send requests through.		no

At most, one of the following can be provided:

authorization block
basic_auth block
bearer_token_file argument
bearer_token argument
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.

The role argument is required to specify what type of targets to discover. role must be one of node, pod, service, endpoints, endpointslice, or ingress.

`node` role

The node role discovers one target per cluster node with the address defaulting to the HTTP port of the kubelet daemon. The target address defaults to the first address of the Kubernetes node object in the address type order of NodeInternalIP, NodeExternalIP, NodeLegacyHostIP, and NodeHostName.

The following labels are included for discovered nodes:

__meta_kubernetes_node_address_<address_type>: The first address for each node address type, if it exists.
__meta_kubernetes_node_annotation_<annotationname>: Each annotation from the node object.
__meta_kubernetes_node_annotationpresent_<annotationname>: Set to true for each annotation from the node object.
__meta_kubernetes_node_label_<labelname>: Each label from the node object.
__meta_kubernetes_node_labelpresent_<labelname>: Set to true for each label from the node object.
__meta_kubernetes_node_name: The name of the node object.
__meta_kubernetes_node_provider_id: The cloud provider’s name for the node object.

In addition, the instance label for the node is set to the node name as retrieved from the API server.

`service` role

The service role discovers a target for each service port for each service. This is generally useful for externally monitoring a service. The address is set to the Kubernetes DNS name of the service and respective service port.

The following labels are included for discovered services:

__meta_kubernetes_namespace: The namespace of the service object.
__meta_kubernetes_service_annotation_<annotationname>: Each annotation from the service object.
__meta_kubernetes_service_annotationpresent_<annotationname>: true for each annotation of the service object.
__meta_kubernetes_service_cluster_ip: The cluster IP address of the service. This doesn’t apply to services of type ExternalName.
__meta_kubernetes_service_external_name: The DNS name of the service. This only applies to services of type ExternalName.
__meta_kubernetes_service_label_<labelname>: Each label from the service object.
__meta_kubernetes_service_labelpresent_<labelname>: true for each label of the service object.
__meta_kubernetes_service_name: The name of the service object.
__meta_kubernetes_service_port_name: Name of the service port for the target.
__meta_kubernetes_service_port_number: Number of the service port for the target.
__meta_kubernetes_service_port_protocol: Protocol of the service port for the target.
__meta_kubernetes_service_type: The type of the service.

`pod` role

The pod role discovers all pods and exposes their containers as targets. For each declared port of a container, a single target is generated.

If a container has no specified ports, a port-free target per container is created. These targets must have a port manually injected using a discovery.relabel component before metrics can be collected from them.

The following labels are included for discovered Pods:

__meta_kubernetes_namespace: The namespace of 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_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_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_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_controller_kind: Object kind of the Pod controller.
__meta_kubernetes_pod_controller_name: Name of the Pod controller.
__meta_kubernetes_pod_host_ip: The current host IP 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_name: The name of the Pod object.
__meta_kubernetes_pod_node_name: The name of the node the Pod is scheduled onto.
__meta_kubernetes_pod_phase: Set to Pending, Running, Succeeded, Failed or Unknown in the lifecycle.
__meta_kubernetes_pod_ready: Set to true or false for the Pod’s ready state.
__meta_kubernetes_pod_uid: The UID of the Pod object.

`endpoints` role

The endpoints role discovers targets from listed endpoints of a service. For each endpoint address one target is discovered per port. If the endpoint is backed by a Pod, all container ports of a Pod are discovered as targets even if they aren’t bound to an endpoint port.

The following labels are included for discovered endpoints:

__meta_kubernetes_endpoints_label_<labelname>: Each label from the endpoints object.
__meta_kubernetes_endpoints_labelpresent_<labelname>: true for each label from the endpoints object.
__meta_kubernetes_endpoints_name: The names of the endpoints object.
__meta_kubernetes_namespace: The namespace of the endpoints object.
The following labels are attached for all targets discovered directly from the endpoints list:
- __meta_kubernetes_endpoint_address_target_kind: Kind of the endpoint address target.
- __meta_kubernetes_endpoint_address_target_name: Name of the endpoint address target.
- __meta_kubernetes_endpoint_hostname: Hostname of the endpoint.
- __meta_kubernetes_endpoint_node_name: Name of the node hosting the endpoint.
- __meta_kubernetes_endpoint_port_name: Name of the endpoint port.
- __meta_kubernetes_endpoint_port_protocol: Protocol of the endpoint port.
- __meta_kubernetes_endpoint_ready: Set to true or false for the endpoint’s ready state.
If the endpoints belong to a service, all labels of the service role discovery are attached.
For all targets backed by a Pod, all labels of the pod role discovery are attached.

`endpointslice` role

The endpointslice role discovers targets from existing Kubernetes endpoint slices. For each endpoint address referenced in the EndpointSlice object, one target is discovered. If the endpoint is backed by a Pod, all container ports of a Pod are discovered as targets even if they’re not bound to an endpoint port.

The following labels are included for discovered endpoint slices:

__meta_kubernetes_endpointslice_name: The name of endpoint slice object.
__meta_kubernetes_namespace: The namespace of the endpoints object.
The following labels are attached for all targets discovered directly from the endpoint slice list:
- __meta_kubernetes_endpointslice_address_target_kind: Kind of the referenced object.
- __meta_kubernetes_endpointslice_address_target_name: Name of referenced object.
- __meta_kubernetes_endpointslice_address_type: The IP protocol family of the address of the target.
- __meta_kubernetes_endpointslice_endpoint_conditions_ready: Set to true or false for the referenced endpoint’s ready state.
- __meta_kubernetes_endpointslice_endpoint_topology_kubernetes_io_hostname: Name of the node hosting the referenced endpoint.
- __meta_kubernetes_endpointslice_endpoint_topology_present_kubernetes_io_hostname: true if the referenced object has a kubernetes.io/hostname annotation.
- __meta_kubernetes_endpointslice_port_name: Named port of the referenced endpoint.
- __meta_kubernetes_endpointslice_port_protocol: Protocol of the referenced endpoint.
- __meta_kubernetes_endpointslice_port: Port of the referenced endpoint.
If the endpoints belong to a service, all labels of the service role discovery are attached.
For all targets backed by a Pod, all labels of the pod role discovery are attached.

`ingress` role

The ingress role discovers a target for each path of each ingress. This is generally useful for externally monitoring an ingress. The address is set to the host specified in the Kubernetes Ingress’s spec block.

The following labels are included for discovered ingress objects:

__meta_kubernetes_ingress_annotation_<annotationname>: Each annotation from the ingress object.
__meta_kubernetes_ingress_annotationpresent_<annotationname>: true for each annotation from the ingress object.
__meta_kubernetes_ingress_class_name: Class name from ingress spec, if present.
__meta_kubernetes_ingress_label_<labelname>: Each label from the ingress object.
__meta_kubernetes_ingress_labelpresent_<labelname>: true for each label from the ingress object.
__meta_kubernetes_ingress_name: The name of the ingress object.
__meta_kubernetes_ingress_path: Path from ingress spec. Defaults to /.
__meta_kubernetes_ingress_scheme: Protocol scheme of ingress, https if TLS config is set. Defaults to http.
__meta_kubernetes_namespace: The namespace of the ingress object.

Blocks

You can use the following blocks with discovery.kubernetes:

Block	Description	Required
`attach_metadata`	Optional metadata to attach to discovered targets.	no
`authorization`	Configure generic authorization to the endpoint.	no
`basic_auth`	Configure `basic_auth` for authenticating to the endpoint.	no
`namespaces`	Information about which Kubernetes namespaces to search.	no
`oauth2`	Configure OAuth 2.0 for authenticating to the endpoint.	no
`oauth2` > `tls_config`	Configure TLS settings for connecting to the endpoint.	no
`selectors`	Selectors to filter discovered Kubernetes resources.	no
`tls_config`	Configure TLS settings for connecting to the endpoint.	no

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

`attach_metadata`

The attach_metadata block allows you to attach node metadata to discovered targets. This block is valid for the pod, endpoints, and endpointslice roles.

Name	Type	Description	Default	Required
`node`	`bool`	Attach node metadata.		no

`authorization`

The authorization block configures generic authorization to the endpoint.

Name	Type	Description	Required
`credentials_file`	`string`	File containing the secret value.	no
`credentials`	`secret`	Secret value.	no
`type`	`string`	Authorization type, for example, “Bearer”.	no

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

`basic_auth`

The basic_auth block configures basic authentication to the endpoint.

Name	Type	Description	Required
`password_file`	`string`	File containing the basic auth password.	no
`password`	`secret`	Basic auth password.	no
`username`	`string`	Basic auth username.	no

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

`namespaces`

The namespaces block limits the namespaces to discover resources in. If you omit this block, all namespaces are searched.

Name	Type	Description	Default	Required
`names`	`list(string)`	List of namespaces to search.		no
`own_namespace`	`bool`	Include the namespace Alloy is running in.		no

`oauth2`

The oauth block configures OAuth 2.0 authentication to the endpoint.

Name	Type	Description	Default	Required
`client_id`	`string`	OAuth2 client ID.		no
`client_secret_file`	`string`	File containing the OAuth2 client secret.		no
`client_secret`	`secret`	OAuth2 client secret.		no
`endpoint_params`	`map(string)`	Optional parameters to append to the token URL.		no
`proxy_url`	`string`	HTTP proxy to send requests through.		no
`no_proxy`	`string`	Comma-separated list of IP addresses, CIDR notations, and domain names to exclude from proxying.		no
`proxy_from_environment`	`bool`	Use the proxy URL indicated by environment variables.	`false`	no
`proxy_connect_header`	`map(list(secret))`	Specifies headers to send to proxies during CONNECT requests.		no
`scopes`	`list(string)`	List of scopes to authenticate with.		no
`token_url`	`string`	URL to fetch the token from.		no

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

`selectors`

The selectors block contains optional label and field selectors to limit the discovery process to a subset of resources.

Name	Type	Description	Required
`role`	`string`	Role of the selector.	yes
`field`	`string`	Field selector string.	no
`label`	`string`	Label selector string.	no

See Kubernetes’ documentation for Field selectors and Labels and selectors to learn more about the possible filters that can be used.

The endpoints role supports Pod, service, and endpoints selectors. The Pod role supports node selectors when configured with attach_metadata: {node: true}. Other roles only support selectors matching the role itself. For example, node role can only contain node selectors.

Note
Using multiple discovery.kubernetes components with different selectors may result in a bigger load against the Kubernetes API.
Selectors are recommended for retrieving a small set of resources in a very large cluster. Smaller clusters are recommended to avoid selectors in favor of filtering with a discovery.relabel component instead.

`tls_config`

The tls_config block configures TLS settings for connecting to the endpoint.

Name	Type	Description	Required
`ca_pem`	`string`	CA PEM-encoded text to validate the server with.	no
`ca_file`	`string`	CA certificate to validate the server with.	no
`cert_pem`	`string`	Certificate PEM-encoded text for client authentication.	no
`cert_file`	`string`	Certificate file for client authentication.	no
`insecure_skip_verify`	`bool`	Disables validation of the server certificate.	no
`key_file`	`string`	Key file for client authentication.	no
`key_pem`	`secret`	Key PEM-encoded text for client authentication.	no
`min_version`	`string`	Minimum acceptable TLS version.	no
`server_name`	`string`	ServerName extension to indicate the name of the server.	no

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 isn’t 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:

Name	Type	Description
`targets`	`list(map(string))`	The set of targets discovered from the Kubernetes API.

Component health

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

Debug information

discovery.kubernetes doesn’t expose any component-specific debug information.

Debug metrics

discovery.kubernetes doesn’t expose any component-specific debug metrics.

Examples

In-cluster discovery

This example uses in-cluster authentication to discover all pods:

discovery.kubernetes "k8s_pods" {
  role = "pod"
}

prometheus.scrape "demo" {
  targets    = discovery.kubernetes.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.

Kubeconfig authentication

This example uses a Kubeconfig file to authenticate to the Kubernetes API:

discovery.kubernetes "k8s_pods" {
  role = "pod"
  kubeconfig_file = "/etc/k8s/kubeconfig.yaml"
}

prometheus.scrape "demo" {
  targets    = discovery.kubernetes.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 and filter by labels value

This example limits the searched namespaces and only selects pods with a specific label value attached to them:

discovery.kubernetes "k8s_pods" {
  role = "pod"

  selectors {
    role = "pod"
    label = "app.kubernetes.io/name=prometheus-node-exporter"
  }

  namespaces {
    names = ["myapp"]
  }
}

prometheus.scrape "demo" {
  targets    = discovery.kubernetes.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 to only pods on the same node

This example limits the search to pods on the same node as this Alloy. This configuration could be useful if you are running Alloy as a DaemonSet.

Note
This example assumes you have used Helm chart to deploy Alloy in Kubernetes and sets HOSTNAME to the Kubernetes host name. If you have a custom Kubernetes Deployment, you must adapt this example to your configuration.

discovery.kubernetes "k8s_pods" {
  role = "pod"
  selectors {
    role = "pod"
    field = "spec.nodeName=" + coalesce(sys.env("HOSTNAME"), constants.hostname)
  }
}

prometheus.scrape "demo" {
  targets    = discovery.kubernetes.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.kubernetes has exports that can be consumed by the following components:

Components that consume Targets

Note
Connecting some components may not be sensible or components may require further configuration to make the connection work correctly. Refer to the linked documentation for more details.

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Feedback

`discovery.kubernetes`

Usage

Arguments

`node` role

`service` role

`pod` role

`endpoints` role

`endpointslice` role

`ingress` role

Blocks

`attach_metadata`

`authorization`

`basic_auth`

`namespaces`

`oauth2`

`selectors`

`tls_config`

Exported fields

Component health

Debug information

Debug metrics

Examples

In-cluster discovery

Kubeconfig authentication

Limit searched namespaces and filter by labels value

Limit to only pods on the same node

Compatible components

Was this page helpful?

Related documentation

discovery.kubernetes

Usage

Arguments

node role

service role

pod role

endpoints role

endpointslice role

ingress role

Blocks

attach_metadata

authorization

basic_auth

namespaces

oauth2

selectors

tls_config

Exported fields

Component health

Debug information

Debug metrics

Examples

In-cluster discovery

Kubeconfig authentication

Limit searched namespaces and filter by labels value

Limit to only pods on the same node

Compatible components

Was this page helpful?

Related documentation

Related resources from Grafana Labs

`discovery.kubernetes`

`node` role

`service` role

`pod` role

`endpoints` role

`endpointslice` role

`ingress` role

`attach_metadata`

`authorization`

`basic_auth`

`namespaces`

`oauth2`

`selectors`

`tls_config`