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loki.source.podlogs

loki.source.podlogs discovers PodLogs resources on Kubernetes. The PodLogs resources provide rules for which Kubernetes Pods to discover on your cluster.

loki.source.podlogs uses the Kubernetes API to tail the logs from the discovered Kubernetes Pods.

loki.source.podlogs is similar to loki.source.kubernetes, but uses custom resources rather than being fed targets from another component.

Note

Because loki.source.podlogs uses the Kubernetes API to tail logs, it uses more network traffic and CPU consumption of Kubelets than loki.source.file.

Multiple loki.source.podlogs components can be specified by giving them different labels.

Usage

alloy
loki.source.podlogs "LABEL" {
  forward_to = RECEIVER_LIST
}

Arguments

The component starts a new reader for each of the given targets and fans out log entries to the list of receivers passed in forward_to.

loki.source.podlogs supports the following arguments:

NameTypeDescriptionDefaultRequired
forward_tolist(LogsReceiver)List of receivers to send log entries to.yes

loki.source.podlogs searches for PodLogs resources on Kubernetes. Each PodLogs resource describes a set of pods to tail logs from.

PodLogs custom resource

The PodLogs resource describes a set of Pods to collect logs from.

Note

loki.source.podlogs looks for PodLogs of monitoring.grafana.com/v1alpha2, and is not compatible with PodLogs from the Agent Operator, which are version v1alpha1.
FieldTypeDescription
apiVersionstringmonitoring.grafana.com/v1alpha2
kindstringPodLogs
metadataObjectMetaMetadata for the PodLogs.
specPodLogsSpecDefinition of what Pods to collect logs from.

PodLogsSpec

PodLogsSpec describes a set of Pods to collect logs from.

FieldTypeDescription
selectorLabelSelectorLabel selector of Pods to collect logs from.
namespaceSelectorLabelSelectorLabel selector of Namespaces that Pods can be discovered in.
relabelingsRelabelConfigRelabel rules to apply to discovered Pods.

If selector is left as the default value, all Pods are discovered. If namespaceSelector is left as the default value, all Namespaces are used for Pod discovery.

The relabelings field can be used to modify labels from discovered Pods. The following meta labels are available for relabeling:

  • __meta_kubernetes_namespace: The namespace of the Pod.
  • __meta_kubernetes_pod_name: The name of the Pod.
  • __meta_kubernetes_pod_ip: The pod IP of the Pod.
  • __meta_kubernetes_pod_label_<labelname>: Each label from the Pod.
  • __meta_kubernetes_pod_labelpresent_<labelname>: true for each label from the Pod.
  • __meta_kubernetes_pod_annotation_<annotationname>: Each annotation from the Pod.
  • __meta_kubernetes_pod_annotationpresent_<annotationname>: true for each annotation from the Pod.
  • __meta_kubernetes_pod_container_init: true if the container is an InitContainer.
  • __meta_kubernetes_pod_container_name: Name of the container.
  • __meta_kubernetes_pod_container_image: The image the container is using.
  • __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.
  • __meta_kubernetes_pod_controller_kind: Object kind of the Pod’s controller.
  • __meta_kubernetes_pod_controller_name: Name of the Pod’s controller.

In addition to the meta labels, the following labels are exposed to tell loki.source.podlogs which container to tail:

  • __pod_namespace__: The namespace of the Pod.
  • __pod_name__: The name of the Pod.
  • __pod_container_name__: The container name within the Pod.
  • __pod_uid__: The UID of the Pod.

Blocks

The following blocks are supported inside the definition of loki.source.podlogs:

HierarchyBlockDescriptionRequired
clientclientConfigures Kubernetes client used to tail logs.no
client > basic_authbasic_authConfigure basic_auth for authenticating to the endpoint.no
client > authorizationauthorizationConfigure generic authorization to the endpoint.no
client > oauth2oauth2Configure OAuth2 for authenticating to the endpoint.no
client > oauth2 > tls_configtls_configConfigure TLS settings for connecting to the endpoint.no
client > tls_configtls_configConfigure TLS settings for connecting to the endpoint.no
selectorselectorLabel selector for which PodLogs to discover.no
selector > match_expressionmatch_expressionLabel selector expression for which PodLogs to discover.no
namespace_selectorselectorLabel selector for which namespaces to discover PodLogs in.no
namespace_selector > match_expressionmatch_expressionLabel selector expression for which namespaces to discover PodLogs in.no
clusteringclusteringConfigure the component for when Alloy is running in clustered mode.no

The > symbol indicates deeper levels of nesting. For example, client > basic_auth refers to a basic_auth block defined inside a client block.

client block

The client block configures the Kubernetes client used to tail logs from containers. If the client block isn’t provided, the default in-cluster configuration with the service account of the running Alloy pod is used.

The following arguments are supported:

NameTypeDescriptionDefaultRequired
api_serverstringURL of the Kubernetes API server.no
kubeconfig_filestringPath of the kubeconfig file to use for connecting to Kubernetes.no
bearer_token_filestringFile containing a bearer token to authenticate with.no
bearer_tokensecretBearer token to authenticate with.no
enable_http2boolWhether HTTP2 is supported for requests.trueno
follow_redirectsboolWhether redirects returned by the server should be followed.trueno
proxy_urlstringHTTP proxy to send requests through.no
no_proxystringComma-separated list of IP addresses, CIDR notations, and domain names to exclude from proxying.no
proxy_from_environmentboolUse the proxy URL indicated by environment variables.falseno
proxy_connect_headermap(list(secret))Specifies headers to send to proxies during CONNECT requests.no

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.

basic_auth block

NameTypeDescriptionDefaultRequired
password_filestringFile containing the basic auth password.no
passwordsecretBasic auth password.no
usernamestringBasic auth username.no

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

authorization block

NameTypeDescriptionDefaultRequired
credentials_filestringFile containing the secret value.no
credentialssecretSecret value.no
typestringAuthorization type, for example, “Bearer”.no

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

oauth2 block

NameTypeDescriptionDefaultRequired
client_idstringOAuth2 client ID.no
client_secret_filestringFile containing the OAuth2 client secret.no
client_secretsecretOAuth2 client secret.no
endpoint_paramsmap(string)Optional parameters to append to the token URL.no
proxy_urlstringHTTP proxy to send requests through.no
no_proxystringComma-separated list of IP addresses, CIDR notations, and domain names to exclude from proxying.no
proxy_from_environmentboolUse the proxy URL indicated by environment variables.falseno
proxy_connect_headermap(list(secret))Specifies headers to send to proxies during CONNECT requests.no
scopeslist(string)List of scopes to authenticate with.no
token_urlstringURL 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

NameTypeDescriptionDefaultRequired
ca_pemstringCA PEM-encoded text to validate the server with.no
ca_filestringCA certificate to validate the server with.no
cert_pemstringCertificate PEM-encoded text for client authentication.no
cert_filestringCertificate file for client authentication.no
insecure_skip_verifyboolDisables validation of the server certificate.no
key_filestringKey file for client authentication.no
key_pemsecretKey PEM-encoded text for client authentication.no
min_versionstringMinimum acceptable TLS version.no
server_namestringServerName 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)

selector block

The selector block describes a Kubernetes label selector for PodLogs or Namespace discovery.

The following arguments are supported:

NameTypeDescriptionDefaultRequired
match_labelsmap(string)Label keys and values used to discover resources.{}no

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 PodLogs or Namespace discovery.

The following arguments are supported:

NameTypeDescriptionDefaultRequired
keystringThe label name to match against.yes
operatorstringThe operator to use when matching.yes
valueslist(string)The values used when matching.no

The operator argument must be one of the following strings:

  • "In"
  • "NotIn"
  • "Exists"
  • "DoesNotExist"

Both selector and namespace_selector can make use of multiple match_expression inner blocks which are treated as AND clauses.

clustering block

NameTypeDescriptionDefaultRequired
enabledboolDistribute log collection with other cluster nodes.yes

When Alloy is using clustering, and enabled is set to true, then this loki.source.podlogs component instance opts-in to participating in the cluster to distribute the load of log collection between all cluster nodes.

If Alloy is not running in clustered mode, then the block is a no-op and loki.source.podlogs collects logs based on every PodLogs resource discovered.

Exported fields

loki.source.podlogs does not export any fields.

Component health

loki.source.podlogs is only reported as unhealthy if given an invalid configuration.

Debug information

loki.source.podlogs exposes some target-level debug information per target:

  • The labels associated with the target.
  • The full set of labels which were found during service discovery.
  • The most recent time a log line was read and forwarded to the next components in the pipeline.
  • The most recent error from tailing, if any.

Debug metrics

loki.source.podlogs does not expose any component-specific debug metrics.

Example

This example discovers all PodLogs resources and forwards collected logs to a loki.write component so they are written to Loki.

alloy
loki.source.podlogs "default" {
  forward_to = [loki.write.local.receiver]
}

loki.write "local" {
  endpoint {
    url = sys.env("LOKI_URL")
  }
}

Compatible components

loki.source.podlogs can accept arguments from the following components:

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.