loki/docs/sources/send-data/otel/_index.md

title	menuTitle	description	aliases	weight
Ingesting logs to Loki using OpenTelemetry Collector	Ingesting OpenTelemetry logs to Loki	Ingesting logs to Loki using OpenTelemetry Collector	[../clients/k6/]	250

Ingesting logs to Loki using OpenTelemetry Collector

{{% admonition type="warning" %}} OpenTelemetry logs ingestion is an experimental feature and is subject to change in future releases of Grafana Loki. {{% /admonition %}}

Loki natively supports ingesting OpenTelemetry logs over HTTP. For ingesting logs to Loki using the OpenTelemetry Collector, you must use the otlphttp exporter.

Loki configuration

When logs are ingested by Loki using an OpenTelemetry protocol (OTLP) ingestion endpoint, some of the data is stored as [Structured Metadata]({{< relref "../../get-started/labels/structured-metadata" >}}). Since Structured Metadata is still an experimental feature, Loki by default rejects any writes using that feature. To start ingesting logs in OpenTelemetry format, you need to enable allow_structured_metadata per tenant configuration (in the limits_config).

Configure the OpenTelemetry Collector to write logs into Loki

You need to make the following changes to the OpenTelemetry Collector config to write logs to Loki on its OTLP ingestion endpoint.

exporters:
  otlphttp:
    endpoint: http://<loki-addr>/otlp

And enable it in service.pipelines:

service:
  pipelines:
    metrics:
      receivers: [...]
      processors: [...]
      exporters: [..., otlphttp]

If you want to authenticate using basic auth, we recommend the basicauth extension.

extensions:
  basicauth/otlp:
    client_auth:
      username: username
      password: password

exporters:
  otlphttp:
    auth:
      authenticator: basicauth/otlp
    endpoint: http://<loki-addr>/otlp

service:
  extensions: [basicauth/otlp]
  pipelines:
    metrics:
      receivers: [...]
      processors: [...]
      exporters: [..., otlphttp]

Format considerations

Since the OpenTelemetry protocol differs from the Loki storage model, here is how data in the OpenTelemetry format will be mapped to the Loki data model during ingestion:

• Index labels: Resource attributes map well to index labels in Loki, since both usually identify the source of the logs. Because Loki has a limit of 30 index labels, we have selected the following resource attributes to be stored as index labels, while the remaining attributes are stored as [Structured Metadata]({{< relref "../../get-started/labels/structured-metadata" >}}) with each log entry:

  • cloud.availability_zone
  • cloud.region
  • container.name
  • deployment.environment
  • k8s.cluster.name
  • k8s.container.name
  • k8s.cronjob.name
  • k8s.daemonset.name
  • k8s.deployment.name
  • k8s.job.name
  • k8s.namespace.name
  • k8s.pod.name
  • k8s.replicaset.name
  • k8s.statefulset.name
  • service.instance.id
  • service.name
  • service.namespace

• Timestamp: One of LogRecord.TimeUnixNano or LogRecord.ObservedTimestamp, based on which one is set. If both are not set, the ingestion timestamp will be used.

• LogLine: LogRecord.Body holds the body of the log. However, since Loki only supports Log body in string format, we will stringify non-string values using the AsString method from the OTEL collector lib.

• [Structured Metadata]({{< relref "../../get-started/labels/structured-metadata" >}}): Anything which can’t be stored in Index labels and LogLine would be stored as Structured Metadata. Here is a non-exhaustive list of what will be stored in Structured Metadata to give a sense of what it will hold:

  • Resource Attributes not stored as Index labels is replicated and stored with each log entry.
  • Everything under InstrumentationScope is replicated and stored with each log entry.
  • Everything under LogRecord except LogRecord.Body, LogRecord.TimeUnixNano and sometimes LogRecord.ObservedTimestamp.

Things to note before ingesting OpenTelemetry logs to Loki:

• Dots (.) are converted to underscores (_).

  Loki does not support . or any other special characters other than _ in label names. The unsupported characters are replaced with an _ while converting Attributes to Index Labels or Structured Metadata. Also, please note that while writing the queries, you must use the normalized format, i.e. use _ instead of special characters while querying data using OTEL Attributes.

  For example, service.name in OTLP would become service_name in Loki.

• Flattening of nested Attributes

  While converting Attributes in OTLP to Index labels or Structured Metadata, any nested attribute values are flattened out using _ as a separator. It is done in a similar way as to how it is done in the LogQL json parser.

• Stringification of non-string Attribute values

  While converting Attribute values in OTLP to Index label values or Structured Metadata, any non-string values are converted to string using AsString method from the OTEL collector lib.