Documentation Grafana Cloud Instrument and send data Grafana Alloy Reference Components otelcol otelcol.receiver.kafka

otelcol.receiver.kafka

otelcol.receiver.kafka accepts telemetry data from a Kafka broker and forwards it to other otelcol.* components.

NOTE: otelcol.receiver.kafka is a wrapper over the upstream OpenTelemetry Collector kafka receiver from the otelcol-contrib distribution. Bug reports or feature requests will be redirected to the upstream repository, if necessary.

Multiple otelcol.receiver.kafka components can be specified by giving them different labels.

Usage

alloy Copy

otelcol.receiver.kafka "LABEL" {
  brokers          = ["BROKER_ADDR"]
  protocol_version = "PROTOCOL_VERSION"

  output {
    metrics = [...]
    logs    = [...]
    traces  = [...]
  }
}

Arguments

The following arguments are supported:

For max_fetch_size, the value 0 means no limit.

If topic is not set, different topics will be used for different telemetry signals:

• Metrics will be received from an otlp_metrics topic.
• Traces will be received from an otlp_spans topic.
• Logs will be received from an otlp_logs topic.

If topic is set to a specific value, then only the signal type that corresponds to the data stored in the topic must be set in the output block. For example, if topic is set to "my_telemetry", then the "my_telemetry" topic can only contain either metrics, logs, or traces. If it contains only metrics, then otelcol.receiver.kafka should be configured to output only metrics.

The encoding argument determines how to decode messages read from Kafka. encoding supports encoding extensions. It tries to load an encoding extension and falls back to internal encodings if no extension was loaded. Available internal encodings:

• "otlp_proto": Decode messages as OTLP protobuf.
• "otlp_json" : Decode messages as OTLP JSON.
• "jaeger_proto": Decode messages as a single Jaeger protobuf span.
• "jaeger_json": Decode messages as a single Jaeger JSON span.
• "zipkin_proto": Decode messages as a list of Zipkin protobuf spans.
• "zipkin_json": Decode messages as a list of Zipkin JSON spans.
• "zipkin_thrift": Decode messages as a list of Zipkin Thrift spans.
• "raw": Copy the log message bytes into the body of a log record.
• "text": Decode the log message as text and insert it into the body of a log record. By default, UTF-8 is used to decode. A different encoding can be chosen by using text_<ENCODING>. For example, text_utf-8 or text_shift_jis.
• "json": Decode the JSON payload and insert it into the body of a log record.
• "azure_resource_logs": The payload is converted from Azure Resource Logs format to an OTLP log.

"otlp_proto" must be used to read all telemetry types from Kafka; other encodings are signal-specific.

initial_offset must be either "latest" or "earliest".

Blocks

The following blocks are supported inside the definition of otelcol.receiver.kafka:

The > symbol indicates deeper levels of nesting. For example, authentication > tls refers to a tls block defined inside an authentication block.

authentication block

The authentication block holds the definition of different authentication mechanisms to use when connecting to Kafka brokers. It doesn’t support any arguments and is configured fully through inner blocks.

plaintext block

The plaintext block configures plain text authentication against Kafka brokers.

The following arguments are supported:

sasl block

The sasl block configures SASL authentication against Kafka brokers.

The following arguments are supported:

The mechanism argument can be set to one of the following strings:

• "PLAIN"
• "AWS_MSK_IAM"
• "SCRAM-SHA-256"
• "SCRAM-SHA-512"

When mechanism is set to "AWS_MSK_IAM", the aws_msk child block must also be provided.

The version argument can be set to either 0 or 1.

aws_msk block

The aws_msk block configures extra parameters for SASL authentication when using the AWS_MSK_IAM mechanism.

The following arguments are supported:

tls block

The tls block configures TLS settings used for connecting to the Kafka brokers. If the tls block isn’t provided, TLS won’t be used for communication.

The following arguments are supported:

If the server doesn’t support TLS, you must set the insecure argument to true.

To disable tls for connections to the server, set the insecure argument to true.

If reload_interval is set to "0s", the certificate never reloaded.

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

If cipher_suites is left blank, a safe default list is used. See the Go TLS documentation for a list of supported cipher suites.

kerberos block

The kerberos block configures Kerberos authentication against the Kafka broker.

The following arguments are supported:

When use_keytab is false, the password argument is required. When use_keytab is true, the file pointed to by the keytab_file argument is used for authentication instead. At most one of password or keytab_file must be provided.

disable_fast_negotiation is useful for Kerberos implementations which do not support PA-FX-FAST (Pre-Authentication Framework - Fast) negotiation.

metadata block

The metadata block configures how to retrieve and store metadata from the Kafka broker.

The following arguments are supported:

If the include_all_topics argument is true, a full set of metadata for all topics is maintained rather than the minimal set that has been necessary so far. Including the full set of metadata is more convenient for users but can consume a substantial amount of memory if you have many topics and partitions.

Retrieving metadata may fail if the Kafka broker is starting up at the same time as the Alloy component. The retry child block can be provided to customize retry behavior.

retry block

The retry block configures how to retry retrieving metadata when retrieval fails.

The following arguments are supported:

autocommit block

The autocommit block configures how to automatically commit updated topic offsets back to the Kafka brokers.

The following arguments are supported:

message_marking block

The message_marking block configures when Kafka messages are marked as read.

The following arguments are supported:

By default, a Kafka message is marked as read immediately after it is retrieved from the Kafka broker. If the after_execution argument is true, messages are only read after the telemetry data is forwarded to components specified in the output block.

When after_execution is true, messages are only marked as read when they are decoded successfully and components where the data was forwarded did not return an error. If the include_unsuccessful argument is true, messages are marked as read even if decoding or forwarding failed. Setting include_unsuccessful has no effect if after_execution is false.

WARNING: Setting after_execution to true and include_unsuccessful to false can block the entire Kafka partition if message processing returns a permanent error, such as failing to decode.

header_extraction block

The header_extraction block configures how to extract headers from Kafka records.

The following arguments are supported:

Regular expressions are not allowed in the headers argument. Only exact matching will be performed.

debug_metrics block

The debug_metrics block configures the metrics that this component generates to monitor its state.

The following arguments are supported:

disable_high_cardinality_metrics is the Grafana Alloy equivalent to the telemetry.disableHighCardinalityMetrics feature gate in the OpenTelemetry Collector. It removes attributes that could cause high cardinality metrics. For example, attributes with IP addresses and port numbers in metrics about HTTP and gRPC connections are removed.

level is the Alloy equivalent to the telemetry.metrics.level feature gate in the OpenTelemetry Collector. Possible values are "none", "basic", "normal" and "detailed".

output block

The output block configures a set of components to forward resulting telemetry data to.

The following arguments are supported:

You must specify the output block, but all its arguments are optional. By default, telemetry data is dropped. Configure the metrics, logs, and traces arguments accordingly to send telemetry data to other components.

Exported fields

otelcol.receiver.kafka does not export any fields.

Component health

otelcol.receiver.kafka is only reported as unhealthy if given an invalid configuration.

Debug information

otelcol.receiver.kafka does not expose any component-specific debug information.

Example

This example forwards read telemetry data through a batch processor before finally sending it to an OTLP-capable endpoint:

alloy Copy

otelcol.receiver.kafka "default" {
  brokers          = ["localhost:9092"]
  protocol_version = "2.0.0"

  output {
    metrics = [otelcol.processor.batch.default.input]
    logs    = [otelcol.processor.batch.default.input]
    traces  = [otelcol.processor.batch.default.input]
  }
}

otelcol.processor.batch "default" {
  output {
    metrics = [otelcol.exporter.otlp.default.input]
    logs    = [otelcol.exporter.otlp.default.input]
    traces  = [otelcol.exporter.otlp.default.input]
  }
}

otelcol.exporter.otlp "default" {
  client {
    endpoint = sys.env("OTLP_ENDPOINT")
  }
}

Compatible components

otelcol.receiver.kafka can accept arguments from the following components:

• Components that export OpenTelemetry otelcol.Consumer