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.

Reference

Components

otelcol

otelcol.exporter.kafka

Open source

otelcol.exporter.kafka

otelcol.exporter.kafka accepts logs, metrics, and traces telemetry data from other otelcol components and sends it to Kafka.

It is important to use otelcol.exporter.kafka together with otelcol.processor.batch to make sure otelcol.exporter.kafka doesn’t slow down due to sending Kafka a huge number of small payloads.

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

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

Usage

otelcol.exporter.kafka "LABEL" {
  protocol_version = "PROTOCOL_VERSION"
}

Arguments

The following arguments are supported:

Name	Type	Description	Default	Required
`protocol_version`	`string`	Kafka protocol version to use.		yes
`brokers`	`list(string)`	Kafka brokers to connect to.	`["localhost:9092"]`	no
`topic`	`string`	Kafka topic to send to.	See below	no
`topic_from_attribute`	`string`	A resource attribute whose value should be used as the message’s topic.	`""`	no
`encoding`	`string`	Encoding of payload read from Kafka.	`"otlp_proto"`	no
`client_id`	`string`	Consumer client ID to use. The ID will be used for all produce requests.	`"sarama"`	no
`timeout`	`duration`	The timeout for every attempt to send data to the backend.	`"5s"`	no
`resolve_canonical_bootstrap_servers_only`	`bool`	Whether to resolve then reverse-lookup broker IPs during startup.	`"false"`	no
`partition_traces_by_id`	`bool`	Whether to include the trace ID as the message key in trace messages sent to Kafka.	`"false"`	no
`partition_metrics_by_resource_attributes`	`bool`	Whether to include the hash of sorted resource attributes as the message partitioning key in metric messages sent to Kafka.	`"false"`	no

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

Metrics will be sent to an otlp_metrics topic.
Traces will be sent to an otlp_spans topic.
Logs will be sent to an otlp_logs topic.

If topic is set, the same topic will be used for all telemetry signals - metrics, logs, and traces.

When topic_from_attribute is set, it will take precedence over topic.

The encoding argument determines how to encode messages sent to Kafka. encoding must be one of the following strings:

Encodings which work for traces, logs, and metrics:
- "otlp_proto": Encode messages as OTLP protobuf.
- "otlp_json": Encode messages as OTLP JSON.
Encodings which work only for traces:
- "jaeger_proto": The payload is serialized to a single Jaeger proto Span, and keyed by TraceID.
- "jaeger_json": The payload is serialized to a single Jaeger JSON Span using jsonpb, and keyed by TraceID.
- "zipkin_proto": The payload is serialized to Zipkin v2 proto Span.
- "zipkin_json": The payload is serialized to Zipkin v2 JSON Span.
Encodings which work only for logs:
- "raw": If the log record body is a byte array, it is sent as is. Otherwise, it is serialized to JSON. Resource and record attributes are discarded.

partition_traces_by_id does not have any effect on Jaeger encoding exporters since Jaeger exporters include trace ID as the message key by default.

Blocks

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

Hierarchy	Block	Description	Required
authentication	authentication	Configures authentication for connecting to Kafka brokers.	no
authentication > plaintext	plaintext	Authenticates against Kafka brokers with plaintext.	no
authentication > sasl	sasl	Authenticates against Kafka brokers with SASL.	no
authentication > sasl > aws_msk	aws_msk	Additional SASL parameters when using AWS_MSK_IAM.	no
authentication > tls	tls	Configures TLS for connecting to the Kafka brokers.	no
authentication > kerberos	kerberos	Authenticates against Kafka brokers with Kerberos.	no
metadata	metadata	Configures how to retrieve metadata from Kafka brokers.	no
metadata > retry	retry	Configures how to retry metadata retrieval.	no
retry_on_failure	retry_on_failure	Configures retry mechanism for failed requests.	no
sending_queue	sending_queue	Configures batching of data before sending.	no
producer	producer	Kafka producer configuration,	no
debug_metrics	debug_metrics	Configures the metrics which this component generates to monitor its state.	no

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:

Name	Type	Description	Default	Required
`username`	`string`	Username to use for plain text authentication.		yes
`password`	`secret`	Password to use for plain text authentication.		yes

sasl block

The sasl block configures SASL authentication against Kafka brokers.

The following arguments are supported:

Name	Type	Description	Default	Required
`username`	`string`	Username to use for SASL authentication.		yes
`password`	`secret`	Password to use for SASL authentication.		yes
`mechanism`	`string`	SASL mechanism to use when authenticating.		yes
`version`	`number`	Version of the SASL Protocol to use when authenticating.	`0`	no

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:

Name	Type	Description	Default	Required
`region`	`string`	AWS region the MSK cluster is based in.		yes
`broker_addr`	`string`	MSK address to connect to for authentication.		yes

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:

Name	Type	Description	Default	Required
`ca_file`	`string`	Path to the CA file.		no
`ca_pem`	`string`	CA PEM-encoded text to validate the server with.		no
`cert_file`	`string`	Path to the TLS certificate.		no
`cert_pem`	`string`	Certificate PEM-encoded text for client authentication.		no
`insecure_skip_verify`	`boolean`	Ignores insecure server TLS certificates.		no
`include_system_ca_certs_pool`	`boolean`	Whether to load the system certificate authorities pool alongside the certificate authority.	`false`	no
`insecure`	`boolean`	Disables TLS when connecting to the configured server.		no
`key_file`	`string`	Path to the TLS certificate key.		no
`key_pem`	`secret`	Key PEM-encoded text for client authentication.		no
`max_version`	`string`	Maximum acceptable TLS version for connections.	`"TLS 1.3"`	no
`min_version`	`string`	Minimum acceptable TLS version for connections.	`"TLS 1.2"`	no
`cipher_suites`	`list(string)`	A list of TLS cipher suites that the TLS transport can use.	`[]`	no
`reload_interval`	`duration`	The duration after which the certificate is reloaded.	`"0s"`	no
`server_name`	`string`	Verifies the hostname of server certificates when set.		no

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:

Name	Type	Description	Required
`service_name`	`string`	Kerberos service name.	no
`realm`	`string`	Kerberos realm.	no
`use_keytab`	`string`	Enables using keytab instead of password.	no
`username`	`string`	Kerberos username to authenticate as.	yes
`password`	`secret`	Kerberos password to authenticate with.	no
`config_file`	`string`	Path to Kerberos location (for example, `/etc/krb5.conf`).	no
`keytab_file`	`string`	Path to keytab file (for example, `/etc/security/kafka.keytab`).	no

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.

metadata block

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

The following arguments are supported:

Name	Type	Description	Default	Required
`include_all_topics`	`bool`	When true, maintains metadata for all topics.	`true`	no

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:

Name	Type	Description	Default	Required
`max_retries`	`number`	How many times to reattempt retrieving metadata.	`3`	no
`backoff`	`duration`	Time to wait between retries.	`"250ms"`	no

retry_on_failure block

The retry_on_failure block configures how failed requests to Kafka are retried.

The following arguments are supported:

Name	Type	Description	Default	Required
`enabled`	`boolean`	Enables retrying failed requests.	`true`	no
`initial_interval`	`duration`	Initial time to wait before retrying a failed request.	`"5s"`	no
`max_elapsed_time`	`duration`	Maximum time to wait before discarding a failed batch.	`"5m"`	no
`max_interval`	`duration`	Maximum time to wait between retries.	`"30s"`	no
`multiplier`	`number`	Factor to grow wait time before retrying.	`1.5`	no
`randomization_factor`	`number`	Factor to randomize wait time before retrying.	`0.5`	no

When enabled is true, failed batches are retried after a given interval. The initial_interval argument specifies how long to wait before the first retry attempt. If requests continue to fail, the time to wait before retrying increases by the factor specified by the multiplier argument, which must be greater than 1.0. The max_interval argument specifies the upper bound of how long to wait between retries.

The randomization_factor argument is useful for adding jitter between retrying Alloy instances. If randomization_factor is greater than 0, the wait time before retries is multiplied by a random factor in the range [ I - randomization_factor * I, I + randomization_factor * I], where I is the current interval.

If a batch hasn’t been sent successfully, it is discarded after the time specified by max_elapsed_time elapses. If max_elapsed_time is set to "0s", failed requests are retried forever until they succeed.

sending_queue block

The sending_queue block configures an in-memory buffer of batches before data is sent to the gRPC server.

The following arguments are supported:

Name	Type	Description	Default	Required
`enabled`	`boolean`	Enables an in-memory buffer before sending data to the client.	`true`	no
`num_consumers`	`number`	Number of readers to send batches written to the queue in parallel.	`10`	no
`queue_size`	`number`	Maximum number of unwritten batches allowed in the queue at the same time.	`1000`	no

When enabled is true, data is first written to an in-memory buffer before sending it to the configured server. Batches sent to the component’s input exported field are added to the buffer as long as the number of unsent batches doesn’t exceed the configured queue_size.

queue_size determines how long an endpoint outage is tolerated. Assuming 100 requests/second, the default queue size 1000 provides about 10 seconds of outage tolerance. To calculate the correct value for queue_size, multiply the average number of outgoing requests per second by the time in seconds that outages are tolerated. A very high value can cause Out Of Memory (OOM) kills.

The num_consumers argument controls how many readers read from the buffer and send data in parallel. Larger values of num_consumers allow data to be sent more quickly at the expense of increased network traffic.

producer block

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

The following arguments are supported:

Name	Type	Description	Default	Required
`max_message_bytes`	`number`	The maximum permitted size of a message in bytes.	`1000000`	no
`required_acks`	`number`	Controls when a message is regarded as transmitted.	`1`	no
`compression`	`string`	Time to wait between retries.	`"none"`	no
`flush_max_messages`	`number`	Time to wait between retries.	`0`	no

Refer to the sarama documentation for more information on required_acks.

compression could be set to either none, gzip, snappy, lz4, or zstd. Refer to the Sarama documentation for more information.

debug_metrics block

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

The following arguments are supported:

Name	Type	Description	Default	Required
`disable_high_cardinality_metrics`	`boolean`	Whether to disable certain high cardinality metrics.	`true`	no
`level`	`string`	Controls the level of detail for metrics emitted by the wrapped collector.	`"detailed"`	no

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.

Note
If configured, disable_high_cardinality_metrics only applies to otelcol.exporter.* and otelcol.receiver.* components.

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

Exported fields

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

Name	Type	Description
`input`	`otelcol.Consumer`	A value that other components can use to send telemetry data to.

input accepts otelcol.Consumer data for any telemetry signal (metrics, logs, or traces).

Component health

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

Debug information

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

Example

This example forwards telemetry data through a batch processor before finally sending it to Kafka:

otelcol.receiver.otlp "default" {
  http {}
  grpc {}

  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.kafka.default.input]
    logs    = [otelcol.exporter.kafka.default.input]
    traces  = [otelcol.exporter.kafka.default.input]
  }
}

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

Compatible components

otelcol.exporter.kafka has exports that can be consumed by the following components:

Components that consume OpenTelemetry otelcol.Consumer

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.

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otelcol.exporter.kafka

Usage

Arguments

Blocks

authentication block

plaintext block

sasl block

aws_msk block

tls block

kerberos block

metadata block

retry block

retry_on_failure block

sending_queue block

producer block

debug_metrics block

Exported fields

Component health

Debug information

Example

Compatible components

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