This is documentation for the next version of Alloy. For the latest stable release, go to the latest version.
discovery.kubelet
discovery.kubelet
discovers Kubernetes pods running on the specified Kubelet and exposes them as scrape targets.
Usage
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:
Name | Type | Description | Default | Required |
---|---|---|---|---|
url | string | URL of the Kubelet server. | “https://localhost:10250” | no |
refresh_interval | duration | How often the Kubelet should be polled for scrape targets | 5s | no |
namespaces | list(string) | A list of namespaces to extract target pods from | 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 |
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 |
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:
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
:
Hierarchy | Block | Description | Required |
---|---|---|---|
basic_auth | basic_auth | Configure basic_auth for authenticating to the endpoint. | no |
authorization | authorization | Configure generic authorization to the endpoint. | no |
oauth2 | oauth2 | Configure OAuth2 for authenticating to the endpoint. | no |
oauth2 > tls_config | tls_config | Configure TLS settings for connecting to the endpoint. | no |
tls_config | 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.
basic_auth block
Name | Type | Description | Default | 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.
authorization block
Name | Type | Description | Default | 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.
oauth2 block
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_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
Name | Type | Description | Default | 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
andca_file
cert_pem
andcert_file
key_pem
andkey_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:
Name | Type | Description |
---|---|---|
targets | list(map(string)) | The set of targets discovered from the Kubelet API. |
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 anInitContainer
.__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 totrue
orfalse
for the pod’s ready state.__meta_kubernetes_pod_phase
: Set toPending
,Running
,Succeeded
,Failed
orUnknown
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.
Note
The Kubelet API used by this component is an internal API and therefore the data in the response returned from the API can’t be guaranteed between different versions of the Kubelet.
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:
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:
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
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.