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General availability (GA) Open source

loki.source.kubernetes

loki.source.kubernetes tails logs from Kubernetes containers using the Kubernetes API.

Note

This component collects logs from Kubernetes Pods. You can’t use this component to collect logs from Kubernetes Nodes.

This component has the following benefits over loki.source.file:

  • It works without a privileged container.
  • It works without a root user.
  • It works without needing access to the filesystem of the Kubernetes node.
  • It doesn’t require a DaemonSet to collect logs, so one Alloy could collect logs for the whole cluster.

Note

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

You can specify multiple loki.source.kubernetes components by giving them different labels.

Usage

alloy 
loki.source.kubernetes "<LABEL>" {
  targets    = <TARGET_LIST>
  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.

You can use the following arguments with loki.source.kubernetes:

NameTypeDescriptionDefaultRequired
forward_tolist(LogsReceiver)List of receivers to send log entries to.yes
targetslist(map(string))List of targets to tail logs from.yes

Each target in targets must have the following labels:

  • __meta_kubernetes_namespace or __pod_namespace__ to specify the namespace of the Pod to tail.
  • __meta_kubernetes_pod_container_name or __pod_container_name__ to specify the container within the Pod to tail.
  • __meta_kubernetes_pod_name or __pod_name__ to specify the name of the Pod to tail.
  • __meta_kubernetes_pod_uid or __pod_uid__ to specify the UID of the Pod to tail.

By default, all of these labels are present when the output discovery.kubernetes is used.

A log tailer is started for each unique target in targets. Log tailers reconnect with exponential backoff to Kubernetes if the log stream returns before the container has permanently terminated.

Blocks

You can use the following blocks with loki.source.kubernetes:

BlockDescriptionRequired
clientConfigures Kubernetes client used to tail logs.no
client > authorizationConfigure generic authorization to the endpoint.no
client > basic_authConfigure basic_auth for authenticating to the endpoint.no
client > oauth2Configure OAuth 2.0 for authenticating to the endpoint.no
client > oauth2 > tls_configConfigure TLS settings for connecting to the endpoint.no
client > tls_configConfigure TLS settings for connecting to the endpoint.no
clusteringConfigure 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

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
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
http_headersmap(list(secret))Custom HTTP headers to be sent along with each request. The map key is the header name.no
kubeconfig_filestringPath of the kubeconfig file to use for connecting to Kubernetes.no
no_proxystringComma-separated list of IP addresses, CIDR notations, and domain names to exclude from proxying.no
proxy_connect_headermap(list(secret))Specifies headers to send to proxies during CONNECT requests.no
proxy_from_environmentboolUse the proxy URL indicated by environment variables.falseno
proxy_urlstringHTTP proxy to send requests through.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.

authorization

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.

Warning

Using credentials_file causes the file to be read on every outgoing request. Use the local.file component with the credentials attribute instead to avoid unnecessary reads.

basic_auth

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.

Warning

Using password_file causes the file to be read on every outgoing request. Use the local.file component with the password attribute instead to avoid unnecessary reads.

oauth2

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
no_proxystringComma-separated list of IP addresses, CIDR notations, and domain names to exclude from proxying.no
proxy_connect_headermap(list(secret))Specifies headers to send to proxies during CONNECT requests.no
proxy_from_environmentboolUse the proxy URL indicated by environment variables.falseno
proxy_urlstringHTTP proxy to send requests through.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.

Warning

Using client_secret_file causes the file to be read on every outgoing request. Use the local.file component with the client_secret attribute instead to avoid unnecessary reads.

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

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 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)

clustering

NameTypeDescriptionDefaultRequired
enabledboolDistribute log collection with other cluster nodes.yes

When Alloy is using clustering, and enabled is set to true, then this loki.source.kubernetes 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.kubernetes collects logs from every target it receives in its arguments.

Clustering looks only at the following labels for determining the shard key:

  • __meta_kubernetes_namespace
  • __meta_kubernetes_pod_container_name
  • __meta_kubernetes_pod_name
  • __meta_kubernetes_pod_uid
  • __pod_container_name__
  • __pod_name__
  • __pod_namespace__
  • __pod_uid__
  • container
  • job
  • namespace
  • pod

Exported fields

loki.source.kubernetes doesn’t export any fields.

Component health

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

Debug information

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

Example

This example collects logs from all Kubernetes Pods and forwards them to a loki.write component so they’re written to Loki.

alloy 
discovery.kubernetes "pods" {
  role = "pod"
}

loki.source.kubernetes "pods" {
  targets    = discovery.kubernetes.pods.targets
  forward_to = [loki.write.local.receiver]
}

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

Compatible components

loki.source.kubernetes 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.