Kafka

Publish observability event data to Apache Kafka topics

status: stable delivery: at-least-once acknowledgements: yes egress: dynamic state: stateless

Configuration

Example configurations

{
  "sinks": {
    "my_sink_id": {
      "type": "kafka",
      "inputs": [
        "my-source-or-transform-id"
      ],
      "bootstrap_servers": "10.14.22.123:9092,10.14.23.332:9092",
      "key_field": "user_id",
      "topic": "topic-1234",
      "acknowledgements": null,
      "batch": null,
      "compression": "none",
      "encoding": {
        "codec": "json"
      },
      "healthcheck": null
    }
  }
}
[sinks.my_sink_id]
type = "kafka"
inputs = [ "my-source-or-transform-id" ]
bootstrap_servers = "10.14.22.123:9092,10.14.23.332:9092"
key_field = "user_id"
topic = "topic-1234"
compression = "none"

  [sinks.my_sink_id.encoding]
  codec = "json"
---
sinks:
  my_sink_id:
    type: kafka
    inputs:
      - my-source-or-transform-id
    bootstrap_servers: 10.14.22.123:9092,10.14.23.332:9092
    key_field: user_id
    topic: topic-1234
    acknowledgements: null
    batch: null
    compression: none
    encoding:
      codec: json
    healthcheck: null
{
  "sinks": {
    "my_sink_id": {
      "type": "kafka",
      "inputs": [
        "my-source-or-transform-id"
      ],
      "bootstrap_servers": "10.14.22.123:9092,10.14.23.332:9092",
      "key_field": "user_id",
      "librdkafka_options": {
        "client.id": "${ENV_VAR}",
        "fetch.error.backoff.ms": "1000",
        "socket.send.buffer.bytes": "100"
      },
      "message_timeout_ms": 300000,
      "sasl": null,
      "socket_timeout_ms": 60000,
      "topic": "topic-1234",
      "buffer": null,
      "acknowledgements": null,
      "batch": null,
      "compression": "none",
      "encoding": {
        "codec": "json"
      },
      "healthcheck": null,
      "tls": null,
      "headers_key": "headers"
    }
  }
}
[sinks.my_sink_id]
type = "kafka"
inputs = [ "my-source-or-transform-id" ]
bootstrap_servers = "10.14.22.123:9092,10.14.23.332:9092"
key_field = "user_id"
message_timeout_ms = 300_000
socket_timeout_ms = 60_000
topic = "topic-1234"
compression = "none"
headers_key = "headers"

  [sinks.my_sink_id.librdkafka_options]
  "client.id" = "${ENV_VAR}"
  "fetch.error.backoff.ms" = "1000"
  "socket.send.buffer.bytes" = "100"

  [sinks.my_sink_id.encoding]
  codec = "json"
---
sinks:
  my_sink_id:
    type: kafka
    inputs:
      - my-source-or-transform-id
    bootstrap_servers: 10.14.22.123:9092,10.14.23.332:9092
    key_field: user_id
    librdkafka_options:
      client.id: ${ENV_VAR}
      fetch.error.backoff.ms: "1000"
      socket.send.buffer.bytes: "100"
    message_timeout_ms: 300000
    sasl: null
    socket_timeout_ms: 60000
    topic: topic-1234
    buffer: null
    acknowledgements: null
    batch: null
    compression: none
    encoding:
      codec: json
    healthcheck: null
    tls: null
    headers_key: headers

acknowledgements

common optional object
Controls how acknowledgements are handled by this sink. When enabled, all connected sources that support end-to-end acknowledgements will wait for the destination of this sink to acknowledge receipt of events before providing acknowledgement to the sending source. These settings override the global acknowledgement settings.

acknowledgements.enabled

common optional bool
Controls if all connected sources will wait for this sink to deliver the events before acknowledging receipt.
default: false

batch

common optional object
Configures the sink batching behavior.

batch.max_bytes

common optional uint
The maximum size of a batch that will be processed by a sink. This is based on the uncompressed size of the batched events, before they are serialized / compressed.

batch.max_events

common optional uint
The maximum size of a batch, in events, before it is flushed.

batch.timeout_secs

common optional float
The maximum age of a batch before it is flushed.

bootstrap_servers

required string literal
A comma-separated list of host and port pairs that are the addresses of the Kafka brokers in a “bootstrap” Kafka cluster that a Kafka client connects to initially to bootstrap itself.
Examples
"10.14.22.123:9092,10.14.23.332:9092"

buffer

optional object

Configures the sink specific buffer behavior.

More information about the individual buffer types, and buffer behavior, can be found in the Buffering Model section.

buffer.max_events

common optional uint
The maximum number of events allowed in the buffer.
Relevant when: type = "memory"
default: 500 (events)

buffer.max_size

required uint
The maximum size of the buffer on the disk. Must be at least ~256 megabytes (268435488 bytes).
Relevant when: type = "disk"
Examples
268435488

buffer.type

common optional string literal enum
The type of buffer to use.
Enum options
OptionDescription
disk

Events are buffered on disk.

This is less performant, but more durable. Data that has been synchronized to disk will not be lost if Vector is restarted forcefully or crashes.

Data is synchronized to disk every 500ms.

memory

Events are buffered in memory.

This is more performant, but less durable. Data will be lost if Vector is restarted forcefully or crashes.

default: memory

buffer.when_full

optional string literal enum
The behavior when the buffer becomes full.
Enum options
OptionDescription
block

Waits for capacity in the buffer.

This will cause backpressure to propagate to upstream components, which can cause data to pile up on the edge.

drop_newest

Drops the event without waiting for capacity in the buffer.

The data is lost. This should only be used when performance is the highest priority.

default: block

compression

common optional string literal enum

The compression strategy used to compress the encoded event data before transmission.

The default compression level of the chosen algorithm is used. Some cloud storage API clients and browsers will handle decompression transparently, so files may not always appear to be compressed depending how they are accessed.

Enum options string literal
OptionDescription
gzipGzip standard DEFLATE compression. Compression level is 6 unless otherwise specified.
lz4lz4 compression.
noneNo compression.
snappySnappy compression.
zstdzstd compression. Compression level is 3 unless otherwise specified. Dictionaries are not supported.
default: none

encoding

required object
Configures the encoding specific sink behavior.

encoding.codec

required string literal enum
The encoding codec used to serialize the events before outputting.
Enum options
OptionDescription
jsonJSON encoded event.
textThe message field from the event.
Examples
"json"
"text"

encoding.except_fields

optional [string]
Prevent the sink from encoding the specified fields.

encoding.only_fields

optional [string]
Makes the sink encode only the specified fields.

encoding.timestamp_format

optional string literal enum
How to format event timestamps.
Enum options
OptionDescription
rfc3339Formats as a RFC3339 string
unixFormats as a unix timestamp
default: rfc3339

headers_key

optional string literal
The log field name to use for the Kafka headers. If omitted, no headers will be written.
Examples
"headers"

healthcheck

common optional object
Health check options for the sink.

healthcheck.enabled

common optional bool
Enables/disables the healthcheck upon Vector boot.
default: true

inputs

required [string]

A list of upstream source or transform IDs. Wildcards (*) are supported.

See configuration for more info.

Array string literal
Examples
[
  "my-source-or-transform-id",
  "prefix-*"
]

key_field

common optional string literal
The log field name or tags key to use for the topic key. If the field does not exist in the log or in tags, a blank value will be used. If unspecified, the key is not sent. Kafka uses a hash of the key to choose the partition or uses round-robin if the record has no key.
Examples
"user_id"

librdkafka_options

optional object
Advanced options. See librdkafka documentation for details.

message_timeout_ms

optional uint
Local message timeout.
Examples
150000
450000
default: 300000

sasl

optional object
Options for SASL/SCRAM authentication support.

sasl.enabled

common optional bool
Enable SASL/SCRAM authentication to the remote. (Not supported on Windows at this time.)

sasl.mechanism

common optional string literal
The Kafka SASL/SCRAM mechanisms.
Examples
"SCRAM-SHA-256"
"SCRAM-SHA-512"

sasl.password

common optional string literal
The Kafka SASL/SCRAM authentication password.
Examples
"password"

sasl.username

common optional string literal
The Kafka SASL/SCRAM authentication username.
Examples
"username"

socket_timeout_ms

optional uint
Default timeout for network requests.
Examples
30000
60000
default: 60000 (milliseconds)

tls

optional object
Configures the TLS options for outgoing connections.

tls.alpn_protocols

optional [string]
Sets the list of supported ALPN protocols, which are used during negotiation with peer. Prioritized in the order they are defined.

tls.ca_file

optional string literal
Absolute path to an additional CA certificate file, in DER or PEM format (X.509), or an inline CA certificate in PEM format.
Examples
"/path/to/certificate_authority.crt"

tls.crt_file

common optional string literal
Absolute path to a certificate file used to identify this connection, in DER or PEM format (X.509) or PKCS#12, or an inline certificate in PEM format. If this is set and is not a PKCS#12 archive, key_file must also be set.
Examples
"/path/to/host_certificate.crt"

tls.enabled

common optional bool
Enable TLS during connections to the remote.
default: false

tls.key_file

common optional string literal
Absolute path to a private key file used to identify this connection, in DER or PEM format (PKCS#8), or an inline private key in PEM format. If this is set, crt_file must also be set.
Examples
"/path/to/host_certificate.key"

tls.key_pass

optional string literal
Pass phrase used to unlock the encrypted key file. This has no effect unless key_file is set.
Examples
"${KEY_PASS_ENV_VAR}"
"PassWord1"

topic

required string template
The Kafka topic name to write events to.
Note: This parameter supports Vector's template syntax, which enables you to use dynamic per-event values.
Examples
"topic-1234"
"logs-{{unit}}-%Y-%m-%d"

Telemetry

Metrics

link

buffer_byte_size

gauge
The number of bytes current in the buffer.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

buffer_discarded_events_total

counter
The number of events dropped by this non-blocking buffer.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

buffer_events

gauge
The number of events currently in the buffer.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

buffer_received_event_bytes_total

counter
The number of bytes received by this buffer.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

buffer_received_events_total

counter
The number of events received by this buffer.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

buffer_sent_event_bytes_total

counter
The number of bytes sent by this buffer.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

buffer_sent_events_total

counter
The number of events sent by this buffer.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

component_received_event_bytes_total

counter
The number of event bytes accepted by this component either from tagged origins like file and uri, or cumulatively from other origins.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
container_name optional
The name of the container from which the data originated.
file optional
The file from which the data originated.
host optional
The hostname of the system Vector is running on.
mode optional
The connection mode used by the component.
peer_addr optional
The IP from which the data originated.
peer_path optional
The pathname from which the data originated.
pid optional
The process ID of the Vector instance.
pod_name optional
The name of the pod from which the data originated.
uri optional
The sanitized URI from which the data originated.

component_received_events_count

histogram

A histogram of the number of events passed in each internal batch in Vector’s internal topology.

Note that this is separate than sink-level batching. It is mostly useful for low level debugging performance issues in Vector due to small internal batches.

component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
container_name optional
The name of the container from which the data originated.
file optional
The file from which the data originated.
host optional
The hostname of the system Vector is running on.
mode optional
The connection mode used by the component.
peer_addr optional
The IP from which the data originated.
peer_path optional
The pathname from which the data originated.
pid optional
The process ID of the Vector instance.
pod_name optional
The name of the pod from which the data originated.
uri optional
The sanitized URI from which the data originated.

component_received_events_total

counter
The number of events accepted by this component either from tagged origins like file and uri, or cumulatively from other origins.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
container_name optional
The name of the container from which the data originated.
file optional
The file from which the data originated.
host optional
The hostname of the system Vector is running on.
mode optional
The connection mode used by the component.
peer_addr optional
The IP from which the data originated.
peer_path optional
The pathname from which the data originated.
pid optional
The process ID of the Vector instance.
pod_name optional
The name of the pod from which the data originated.
uri optional
The sanitized URI from which the data originated.

component_sent_bytes_total

counter
The number of raw bytes sent by this component to destination sinks.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
endpoint optional
The endpoint to which the bytes were sent. For HTTP, this will be the host and path only, excluding the query string.
file optional
The absolute path of the destination file.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.
protocol
The protocol used to send the bytes.
region optional
The AWS region name to which the bytes were sent. In some configurations, this may be a literal hostname.

component_sent_event_bytes_total

counter
The total number of event bytes emitted by this component.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
output optional
The specific output of the component.
pid optional
The process ID of the Vector instance.

component_sent_events_total

counter
The total number of events emitted by this component.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
output optional
The specific output of the component.
pid optional
The process ID of the Vector instance.

events_discarded_total

counter
The total number of events discarded by this component.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.
reason
The type of the error

events_in_total

counter
The number of events accepted by this component either from tagged origins like file and uri, or cumulatively from other origins. This metric is deprecated and will be removed in a future version. Use component_received_events_total instead.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
container_name optional
The name of the container from which the data originated.
file optional
The file from which the data originated.
host optional
The hostname of the system Vector is running on.
mode optional
The connection mode used by the component.
peer_addr optional
The IP from which the data originated.
peer_path optional
The pathname from which the data originated.
pid optional
The process ID of the Vector instance.
pod_name optional
The name of the pod from which the data originated.
uri optional
The sanitized URI from which the data originated.

kafka_consumed_messages_bytes_total

counter
Total number of message bytes (including framing) received from Kafka brokers.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

kafka_consumed_messages_total

counter
Total number of messages consumed, not including ignored messages (due to offset, etc), from Kafka brokers.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

kafka_produced_messages_bytes_total

counter
Total number of message bytes (including framing, such as per-Message framing and MessageSet/batch framing) transmitted to Kafka brokers.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

kafka_produced_messages_total

counter
Total number of messages transmitted (produced) to Kafka brokers.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

kafka_queue_messages

gauge
Current number of messages in producer queues.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

kafka_queue_messages_bytes

gauge
Current total size of messages in producer queues.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

kafka_requests_bytes_total

counter
Total number of bytes transmitted to Kafka brokers.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

kafka_requests_total

counter
Total number of requests sent to Kafka brokers.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

kafka_responses_bytes_total

counter
Total number of bytes received from Kafka brokers.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

kafka_responses_total

counter
Total number of responses received from Kafka brokers.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

processing_errors_total

counter
The total number of processing errors encountered by this component. This metric is deprecated in favor of component_errors_total.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
error_type
The type of the error
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

utilization

gauge
A ratio from 0 to 1 of the load on a component. A value of 0 would indicate a completely idle component that is simply waiting for input. A value of 1 would indicate a that is never idle. This value is updated every 5 seconds.
component_id
The Vector component ID.
component_kind
The Vector component kind.
component_name
Deprecated, use component_id instead. The value is the same as component_id.
component_type
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

How it works

Azure Event Hubs

It is possible to use the kafka source and sink with Azure Event Hubs for all tiers other than the Basic tier. More details can be found here. To configure the source and sink to connect to Azure Event Hubs set the following options:

  • bootstrap_servers - <namespace name>.servicebus.windows.net:9093
  • group_id - The consumer group. Note that if the default group ($Default) is used it must be specified as $$Default to escape the $ used for environment variables.
  • topics - The event hub name.
  • sasl.enabled - Set to true.
  • sasl.mechanism - Set to PLAIN.
  • sasl.username - Set to $$ConnectionString (note the double $$).
  • sasl.password - Set to the connection string. See here.
  • tls.enabled - Set to true.
  • tls.ca_file - The certificate authority file.
  • tls.verify_certificate - Set to true.

Buffers and batches

This component buffers & batches data as shown in the diagram above. You’ll notice that Vector treats these concepts differently, instead of treating them as global concepts, Vector treats them as sink specific concepts. This isolates sinks, ensuring services disruptions are contained and delivery guarantees are honored.

Batches are flushed when 1 of 2 conditions are met:

  1. The batch age meets or exceeds the configured timeout_secs.
  2. The batch size meets or exceeds the configured max_bytes or max_events.

Buffers are controlled via the buffer.* options.

Health checks

Health checks ensure that the downstream service is accessible and ready to accept data. This check is performed upon sink initialization. If the health check fails an error will be logged and Vector will proceed to start.

Require health checks

If you’d like to exit immediately upon a health check failure, you can pass the --require-healthy flag:

vector --config /etc/vector/vector.toml --require-healthy

Disable health checks

If you’d like to disable health checks for this sink you can set the healthcheck option to false.

librdkafka

The kafka sink uses librdkafka under the hood. This is a battle-tested, high performance, and reliable library that facilitates communication with Kafka. As Vector produces static MUSL builds, this dependency is packaged with Vector, meaning you do not need to install it.

State

This component is stateless, meaning its behavior is consistent across each input.

Transport Layer Security (TLS)

Vector uses OpenSSL for TLS protocols due to OpenSSL’s maturity. You can enable and adjust TLS behavior using the tls.* options.