Kafka binding spec
- Component format
- Spec metadata fields
  - Note
Binding support
Authentication
Specifying a partition key
- Response
Related links

Kafka binding spec

Detailed documentation on the Kafka binding component

Component format

To setup Kafka binding create a component of type bindings.kafka. See this guide on how to create and apply a binding configuration. For details on using secretKeyRef, see the guide on how to reference secrets in components.

All component metadata field values can carry templated metadata values, which are resolved on Dapr sidecar startup. For example, you can choose to use {namespace} as the consumerGroup, to enable using the same appId in different namespaces using the same topics as described in this article.

apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: kafka-binding
spec:
  type: bindings.kafka
  version: v1
  metadata:
  - name: topics # Optional. Used for input bindings.
    value: "topic1,topic2"
  - name: brokers # Required.
    value: "localhost:9092,localhost:9093"
  - name: consumerGroup # Optional. Used for input bindings.
    value: "group1"
  - name: publishTopic # Optional. Used for output bindings.
    value: "topic3"
  - name: authRequired # Required.
    value: "true"
  - name: saslUsername # Required if authRequired is `true`.
    value: "user"
  - name: saslPassword # Required if authRequired is `true`.
    secretKeyRef:
      name: kafka-secrets
      key: "saslPasswordSecret"
  - name: saslMechanism
    value: "SHA-512"
  - name: initialOffset # Optional. Used for input bindings.
    value: "newest"
  - name: maxMessageBytes # Optional.
    value: "1024"
  - name: version # Optional.
    value: "2.0.0"
  - name: direction
    value: "input, output"
  - name: schemaRegistryURL # Optional. When using Schema Registry Avro serialization/deserialization. The Schema Registry URL.
    value: http://localhost:8081
  - name: schemaRegistryAPIKey # Optional. When using Schema Registry Avro serialization/deserialization. The Schema Registry API Key.
    value: XYAXXAZ
  - name: schemaRegistryAPISecret # Optional. When using Schema Registry Avro serialization/deserialization. The Schema Registry credentials API Secret.
    value: "ABCDEFGMEADFF"
  - name: schemaCachingEnabled # Optional. When using Schema Registry Avro serialization/deserialization. Enables caching for schemas.
    value: true
  - name: schemaLatestVersionCacheTTL # Optional. When using Schema Registry Avro serialization/deserialization. The TTL for schema caching when publishing a message with latest schema available.
    value: 5m

Spec metadata fields

Field	Required	Binding support	Details	Example
`topics`	N	Input	A comma-separated string of topics.	`“mytopic1,topic2”`
`brokers`	Y	Input/Output	A comma-separated string of Kafka brokers.	`“localhost:9092,dapr-kafka.myapp.svc.cluster.local:9093”`
`clientID`	N	Input/Output	A user-provided string sent with every request to the Kafka brokers for logging, debugging, and auditing purposes.	`“my-dapr-app”`
`consumerGroup`	N	Input	A kafka consumer group to listen on. Each record published to a topic is delivered to one consumer within each consumer group subscribed to the topic.	`“group1”`
`consumeRetryEnabled`	N	Input/Output	Enable consume retry by setting to `“true”`. Default to `false` in Kafka binding component.	`“true”`, `“false”`
`publishTopic`	Y	Output	The topic to publish to.	`“mytopic”`
`authRequired`	N	Deprecated	Enable SASL authentication with the Kafka brokers.	`“true”`, `“false”`
`authType`	Y	Input/Output	Configure or disable authentication. Supported values: `none`, `password`, `mtls`, or `oidc`	`“password”`, `“none”`
`saslUsername`	N	Input/Output	The SASL username used for authentication. Only required if `authRequired` is set to `“true”`.	`“adminuser”`
`saslPassword`	N	Input/Output	The SASL password used for authentication. Can be `secretKeyRef` to use a secret reference. Only required if `authRequired` is set to `“true”`.	`“”`, `“KeFg23!”`
`saslMechanism`	N	Input/Output	The SASL authentication mechanism you’d like to use. Only required if `authtype` is set to `“password”`. If not provided, defaults to `PLAINTEXT`, which could cause a break for some services, like Amazon Managed Service for Kafka.	`“SHA-512”, “SHA-256”, “PLAINTEXT”`
`initialOffset`	N	Input	The initial offset to use if no offset was previously committed. Should be “newest” or “oldest”. Defaults to “newest”.	`“oldest”`
`maxMessageBytes`	N	Input/Output	The maximum size in bytes allowed for a single Kafka message. Defaults to 1024.	`“2048”`
`oidcTokenEndpoint`	N	Input/Output	Full URL to an OAuth2 identity provider access token endpoint. Required when `authType` is set to `oidc`	“https://identity.example.com/v1/token”
`oidcClientID`	N	Input/Output	The OAuth2 client ID that has been provisioned in the identity provider. Required when `authType` is set to `oidc`	`“dapr-kafka”`
`oidcClientSecret`	N	Input/Output	The OAuth2 client secret that has been provisioned in the identity provider: Required when `authType` is set to `oidc`	`“KeFg23!”`
`oidcScopes`	N	Input/Output	Comma-delimited list of OAuth2/OIDC scopes to request with the access token. Recommended when `authType` is set to `oidc`. Defaults to `“openid”`	`“openid,kafka-prod”`
`version`	N	Input/Output	Kafka cluster version. Defaults to 2.0.0. Please note that this needs to be mandatorily set to `1.0.0` for EventHubs with Kafka.	`“1.0.0”`
`direction`	N	Input/Output	The direction of the binding.	`“input”`, `“output”`, `“input, output”`
`oidcExtensions`	N	Input/Output	String containing a JSON-encoded dictionary of OAuth2/OIDC extensions to request with the access token	`{“cluster”:”kafka”,”poolid”:”kafkapool”}`
`schemaRegistryURL`	N	Required when using Schema Registry Avro serialization/deserialization. The Schema Registry URL.	`http://localhost:8081`
`schemaRegistryAPIKey`	N	When using Schema Registry Avro serialization/deserialization. The Schema Registry credentials API Key.	`XYAXXAZ`
`schemaRegistryAPISecret`	N	When using Schema Registry Avro serialization/deserialization. The Schema Registry credentials API Secret.	`ABCDEFGMEADFF`
`schemaCachingEnabled`	N	When using Schema Registry Avro serialization/deserialization. Enables caching for schemas. Default is `true`	`true`
`schemaLatestVersionCacheTTL`	N	When using Schema Registry Avro serialization/deserialization. The TTL for schema caching when publishing a message with latest schema available. Default is 5 min	`5m`

Note

The metadata version must be set to 1.0.0 when using Azure EventHubs with Kafka.

Binding support

This component supports both input and output binding interfaces.

This component supports output binding with the following operations:

create

Authentication

Kafka supports a variety of authentication schemes and Dapr supports several: SASL password, mTLS, OIDC/OAuth2. Learn more about Kafka’s authentication method for both the Kafka binding and Kafka pub/sub components.

Specifying a partition key

When invoking the Kafka binding, its possible to provide an optional partition key by using the metadata section in the request body.

The field name is partitionKey.

Example:

curl -X POST http://localhost:3500/v1.0/bindings/myKafka \
  -H "Content-Type: application/json" \
  -d '{
        "data": {
          "message": "Hi"
        },
        "metadata": {
          "partitionKey": "key1"
        },
        "operation": "create"
      }'

Response

An HTTP 204 (No Content) and empty body will be returned if successful.

Kafka