Reference

Components

loki

loki.rules.kubernetes

Open source

loki.rules.kubernetes

loki.rules.kubernetes discovers PrometheusRule Kubernetes resources and loads them into a Loki instance.

You can specify multiple loki.rules.kubernetes components by giving them different labels.
Kubernetes label selectors can be used to limit the Namespace and PrometheusRule resources considered during reconciliation.
Compatible with the Ruler APIs of Grafana Loki, Grafana Cloud, and Grafana Enterprise Metrics.
Compatible with the PrometheusRule CRD from the prometheus-operator.
This component accesses the Kubernetes REST API from within a Pod.

Note
This component requires Role-based access control (RBAC) to be set up in Kubernetes for Alloy to access it via the Kubernetes REST API.

Usage

loki.rules.kubernetes "LABEL" {
  address = LOKI_RULER_URL
}

Arguments

loki.rules.kubernetes supports the following arguments:

Name	Type	Description	Default	Required
`address`	`string`	URL of the Loki ruler.		yes
`tenant_id`	`string`	Loki tenant ID.		no
`use_legacy_routes`	`bool`	Whether to use deprecated ruler API endpoints.	false	no
`sync_interval`	`duration`	Amount of time between reconciliations with Loki.	“30s”	no
`loki_namespace_prefix`	`string`	Prefix used to differentiate multiple Alloy deployments.	“alloy”	no
`bearer_token`	`secret`	Bearer token to authenticate with.		no
`bearer_token_file`	`string`	File containing a bearer token to authenticate with.		no
`proxy_url`	`string`	HTTP proxy to proxy requests through.		no
`follow_redirects`	`bool`	Whether redirects returned by the server should be followed.	`true`	no
`enable_http2`	`bool`	Whether HTTP2 is supported for requests.	`true`	no

At most, one of the following can be provided:

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

If no tenant_id is provided, the component assumes that the Loki instance at address is running in single-tenant mode and no X-Scope-OrgID header is sent.

The sync_interval argument determines how often Loki’s ruler API is accessed to reload the current state. Interaction with the Kubernetes API works differently. Updates are processed as events from the Kubernetes API server according to the informer pattern.

You can use the loki_namespace_prefix argument to separate the rules managed by multiple Alloy deployments across your infrastructure. You should set the prefix to a unique value for each deployment.

Blocks

The following blocks are supported inside the definition of loki.rules.kubernetes:

Hierarchy	Block	Description	Required
rule_namespace_selector	label_selector	Label selector for `Namespace` resources.	no
rule_namespace_selector > match_expression	match_expression	Label match expression for `Namespace` resources.	no
rule_selector	label_selector	Label selector for `PrometheusRule` resources.	no
rule_selector > match_expression	match_expression	Label match expression for `PrometheusRule` resources.	no
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.

label_selector block

The label_selector block describes a Kubernetes label selector for rule or namespace discovery.

The following arguments are supported:

Name	Type	Description	Default	Required
`match_labels`	`map(string)`	Label keys and values used to discover resources.	`{}`	yes

When the match_labels argument is empty, all resources will be matched.

match_expression block

The match_expression block describes a Kubernetes label match expression for rule or namespace discovery.

The following arguments are supported:

Name	Type	Description	Required
`key`	`string`	The label name to match against.	yes
`operator`	`string`	The operator to use when matching.	yes
`values`	`list(string)`	The values used when matching.	no

The operator argument should be one of the following strings:

"in"
"notin"
"exists"

basic_auth block

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.

authorization block

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.

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	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 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

loki.rules.kubernetes does not export any fields.

Component health

loki.rules.kubernetes is reported as unhealthy if given an invalid configuration or an error occurs during reconciliation.

Debug information

loki.rules.kubernetes exposes resource-level debug information.

The following are exposed per discovered PrometheusRule resource:

The Kubernetes namespace.
The resource name.
The resource uid.
The number of rule groups.

The following are exposed per discovered Loki rule namespace resource:

The namespace name.
The number of rule groups.

Only resources managed by the component are exposed - regardless of how many actually exist.

Debug metrics

Metric Name	Type	Description
`loki_rules_config_updates_total`	`counter`	Number of times the configuration has been updated.
`loki_rules_events_total`	`counter`	Number of events processed, partitioned by event type.
`loki_rules_events_failed_total`	`counter`	Number of events that failed to be processed, partitioned by event type.
`loki_rules_events_retried_total`	`counter`	Number of events that were retried, partitioned by event type.
`loki_rules_client_request_duration_seconds`	`histogram`	Duration of requests to the Loki API.

Example

This example creates a loki.rules.kubernetes component that loads discovered rules to a local Loki instance under the team-a tenant. Only namespaces and rules with the alloy label set to yes are included.

loki.rules.kubernetes "local" {
    address = "loki:3100"
    tenant_id = "team-a"

    rule_namespace_selector {
        match_labels = {
            alloy = "yes",
        }
    }

    rule_selector {
        match_labels = {
            alloy = "yes",
        }
    }
}

This example creates a loki.rules.kubernetes component that loads discovered rules to Grafana Cloud.

loki.rules.kubernetes "default" {
    address = "GRAFANA_CLOUD_URL"
    basic_auth {
        username = "GRAFANA_CLOUD_USER"
        password = "GRAFANA_CLOUD_API_KEY"
        // Alternatively, load the password from a file:
        // password_file = "GRAFANA_CLOUD_API_KEY_PATH"
    }
}

The following example is an RBAC configuration for Kubernetes. It authorizes Alloy to query the Kubernetes REST API:

apiVersion: v1
kind: ServiceAccount
metadata:
  name: alloy
  namespace: default
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: alloy
rules:
- apiGroups: [""]
  resources: ["namespaces"]
  verbs: ["get", "list", "watch"]
- apiGroups: ["monitoring.coreos.com"]
  resources: ["prometheusrules"]
  verbs: ["get", "list", "watch"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: alloy
subjects:
- kind: ServiceAccount
  name: alloy
  namespace: default
roleRef:
  kind: ClusterRole
  name: alloy
  apiGroup: rbac.authorization.k8s.io