loki.write.md

---

title: loki.write

---

loki.write

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.

Usage

loki.write "LABEL" {
  endpoint {
    url = REMOTE_WRITE_URL
  }
}

Arguments

loki.write supports the following arguments:

Name	Type	Description	Default	Required
max_streams	int	Time to wait before marking a request as failed.	"5s"	no
external_labels	map(string)	Labels to add to logs sent over the network.		no

Blocks

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

Hierarchy	Block	Description	Required
endpoint	endpoint	Location to send logs to.	no
endpoint > basic_auth	basic_auth	Configure basic_auth for authenticating to the endpoint.	no
endpoint > authorization	authorization	Configure generic authorization to the endpoint.	no
endpoint > oauth2	oauth2	Configure OAuth2 for authenticating to the endpoint.	no
endpoint > oauth2 > tls_config	tls_config	Configure TLS settings for connecting to the endpoint.	no
endpoint > tls_config	tls_config	Configure TLS settings for connecting to the endpoint.	no

The > symbol indicates deeper levels of nesting. For example, endpoint > basic_auth refers to a basic_auth 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:

Name	Type	Description	Default	Required
url	string	Full URL to send logs to.		yes
name	string	Optional name to identify this endpoint with.		no
batch_wait	duration	Maximum amount of time to wait before sending a batch.	"1s"	no
batch_size	string	Maximum batch size of logs to accumulate before sending.	"1MiB"	no
remote_timeout	duration	Timeout for requests made to the URL.	"10s"	no
tenant_id	string	The tenant ID used by default to push logs.		no
min_backoff_period	duration	Initial backoff time between retries.	"500ms"	no
max_backoff_period	duration	Maximum backoff time between retries.	"5m"	no
max_backoff_retries	int	Maximum number of retries.	10	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 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.

basic_auth block

{{< docs/shared lookup="flow/reference/components/basic-auth-block.md" source="agent" >}}

authorization block

{{< docs/shared lookup="flow/reference/components/authorization-block.md" source="agent" >}}

oauth2 block

{{< docs/shared lookup="flow/reference/components/oauth2-block.md" source="agent" >}}

tls_config block

{{< docs/shared lookup="flow/reference/components/tls-config-block.md" source="agent" >}}

Exported fields

The following fields are exported and can be referenced by other components:

Name	Type	Description
receiver	LogsReceiver	A 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.

Example

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

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