Important: This documentation is about an older version. It's relevant only to the release noted, many of the features and functions have been updated or replaced. Please view the current version.

Open source


loki.write receives log entries from other loki components and sends them over the network using Loki’s logproto format.

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


loki.write "LABEL" {
  endpoint {


loki.write supports the following arguments:

max_streamsintTime to wait before marking a request as failed."5s"no
external_labelsmap(string)Labels to add to logs sent over the


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

endpointendpointLocation to send logs
endpoint > http_client_confighttp_client_configHTTP client settings when connecting to the
endpoint > http_client_config > basic_authbasic_authConfigure basic_auth for authenticating to the
endpoint > http_client_config > authorizationauthorizationConfigure generic authorization to the
endpoint > http_client_config > oauth2oauth2Configure OAuth2 for authenticating to the
endpoint > http_client_config > oauth2 > tls_configtls_configConfigure TLS settings for connecting to the
endpoint > http_client_config > tls_configtls_configConfigure TLS settings for connecting to the

The > symbol indicates deeper levels of nesting. For example, endpoint > http_client_config refers to an http_client_config block defined inside an endpoint block.

endpoint block

The endpoint block describes a single location to send logs to. Multiple endpoint blocks can be provided to send logs to multiple locations.

The following arguments are supported:

urlstringFull URL to send logs to.yes
namestringOptional name to identify this endpoint
batch_waitboolMaximum amount of time to wait before sending a batch."1s"no
batch_sizestringMaximum batch size of logs to accumulate before sending."1MiB"no
remote_timeoutdurationTimeout for requests made to the URL."10s"no
tenant_idstringThe tenant ID used by default to push
min_backoff_perioddurationInitial backoff time between retries."500ms"no
max_backoff_perioddurationMaximum backoff time between retries."5m"no
max_backoff_retriesintMaximum number of retries.10no

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

When multiple endpoint blocks are provided, the loki.write component creates a client for each. Received log entries are fanned-out to these clients in succession. That means that if one client is bottlenecked, it may impact the rest.

Endpoints can be named for easier identification in debug metrics by using the name argument. If the name argument isn’t provided, a name is generated based on a hash of the endpoint settings.

http_client_config block

The http_client_config configures settings used to connect to the Loki API.

bearer_tokensecretBearer token to authenticate
bearer_token_filestringFile containing a bearer token to authenticate
proxy_urlstringHTTP proxy to proxy requests
follow_redirectsboolWhether redirects returned by the server should be followed.trueno
enable_http_2boolWhether HTTP2 is supported for requests.trueno

bearer_token, bearer_token_file, basic_auth, authorization, and oauth2 are mutually exclusive and only one can be provided inside of a http_client_config block.

basic_auth block

usernamestringBasic auth
passwordsecretBasic auth
password_filestringFile containing the basic auth

password and password_file are mututally exclusive and only one can be provided inside of a basic_auth block.

authorization block

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

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

oauth2 block

client_idstringOAuth2 client
client_secretsecretOAuth2 client
client_secret_filestringFile containing the OAuth2 client
scopeslist(string)List of scopes to authenticate
token_urlstringURL to fetch the token
endpoint_paramsmap(string)Optional parameters to append to the token
proxy_urlstringOptional proxy URL for OAuth2

client_secret and client_secret_file are mututally exclusive and only one can be provided inside of an oauth2 block.

The oauth2 block may also contain its own separate tls_config sub-block.

tls_config block

ca_filestringCA certificate to validate the server
cert_filestringCertificate file for client
key_filestringKey file for client
server_namestringServerName extension to indicate the name of the
insecure_skip_verifyboolDisables validation of the server
min_versionstringMinimum acceptable TLS

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:

receiverLogsReceiverA value that other components can use to send log entries to.

Component health

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

Debug information

loki.write does not expose any component-specific debug information.

Debug metrics

  • loki_write_encoded_bytes_total (counter): Number of bytes encoded and ready to send.
  • loki_write_sent_bytes_total (counter): Number of bytes sent.
  • loki_write_dropped_bytes_total (counter): Number of bytes dropped because failed to be sent to the ingester after all retries.
  • loki_write_sent_entries_total (counter): Number of log entries sent to the ingester.
  • loki_write_dropped_entries_total (counter): Number of log entries dropped because they failed to be sent to the ingester after all retries.
  • loki_write_request_duration_seconds (histogram): Duration of sent requests.
  • loki_write_batch_retries_total (counter): Number of times batches have had to be retried.
  • loki_write_stream_lag_seconds (gauge): Difference between current time and last batch timestamp for successful sends.


This example creates a loki.write component that sends received entries to a local Loki instance:

loki.write "local" {
    endpoint {
        url = "loki:3100"