Kafka Upstream: Simple JSON encoding for Avro schemas - Plugin

Simple JSON encoding for Avro schemasv3.16+

Configure the Kafka Upstream plugin to accept plain JSON for an Avro schema with nullable fields, instead of Avro-encoded JSON with type-tagged unions.

Prerequisites

Kafka installed and running
Create a Kafka topic
Schema Registry configured with an Avro schema that includes at least one nullable (union) field

Environment variables

KAFKA_TOPIC: The name of your Kafka topic.
BOOTSTRAP_SERVER_HOST: The bootstrap server host.
REGISTRY_URL: The URL of your Confluent Schema Registry instance. For example, http://schema-registry:8081.

Set up the plugin

Add this section to your kong.yaml configuration file:

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kong.yaml

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_format_version: "3.0"
plugins:
  - name: kafka-upstream
    config:
      bootstrap_servers:
      - host: ${{ env "DECK_BOOTSTRAP_SERVER_HOST" }}
        port: 9092
      topic: ${{ env "DECK_KAFKA_TOPIC" }}
      schema_registry:
        confluent:
          url: ${{ env "DECK_REGISTRY_URL" }}
          authentication:
            mode: basic
            basic:
              username: user
              password: password
          value_schema:
            subject_name: kong-value
            schema_version: latest
            payload_encoding: simple_json
      message_by_lua_functions:
      - return function(message) return message.body end

Make the following request:

curl -i -X POST http://localhost:8001/plugins/ \
    --header "Accept: application/json" \
    --header "Content-Type: application/json" \
    --data '
    {
      "name": "kafka-upstream",
      "config": {
        "bootstrap_servers": [
          {
            "host": "'$BOOTSTRAP_SERVER_HOST'",
            "port": 9092
          }
        ],
        "topic": "'$KAFKA_TOPIC'",
        "schema_registry": {
          "confluent": {
            "url": "'$REGISTRY_URL'",
            "authentication": {
              "mode": "basic",
              "basic": {
                "username": "user",
                "password": "password"
              }
            },
            "value_schema": {
              "subject_name": "kong-value",
              "schema_version": "latest",
              "payload_encoding": "simple_json"
            }
          }
        },
        "message_by_lua_functions": [
          "return function(message) return message.body end"
        ]
      }
    }
    '

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Make the following request:

curl -X POST https://{region}.api.konghq.com/v2/control-planes/{controlPlaneId}/core-entities/plugins/ \
    --header "accept: application/json" \
    --header "Content-Type: application/json" \
    --header "Authorization: Bearer $KONNECT_TOKEN" \
    --data '
    {
      "name": "kafka-upstream",
      "config": {
        "bootstrap_servers": [
          {
            "host": "'$BOOTSTRAP_SERVER_HOST'",
            "port": 9092
          }
        ],
        "topic": "'$KAFKA_TOPIC'",
        "schema_registry": {
          "confluent": {
            "url": "'$REGISTRY_URL'",
            "authentication": {
              "mode": "basic",
              "basic": {
                "username": "user",
                "password": "password"
              }
            },
            "value_schema": {
              "subject_name": "kong-value",
              "schema_version": "latest",
              "payload_encoding": "simple_json"
            }
          }
        },
        "message_by_lua_functions": [
          "return function(message) return message.body end"
        ]
      }
    }
    '

Copied!

Make sure to replace the following placeholders with your own values:

region: Geographic region where your Kong Konnect is hosted and operates.
KONNECT_TOKEN: Your Personal Access Token (PAT) associated with your Konnect account.
controlPlaneId: The id of the control plane.

See the Konnect Control Planes Config API reference to learn about region-specific URLs and personal access tokens.

echo "
apiVersion: configuration.konghq.com/v1
kind: KongClusterPlugin
metadata:
  name: kafka-upstream
  namespace: kong
  annotations:
    kubernetes.io/ingress.class: kong
  labels:
    global: 'true'
config:
  bootstrap_servers:
  - host: '$BOOTSTRAP_SERVER_HOST'
    port: 9092
  topic: '$KAFKA_TOPIC'
  schema_registry:
    confluent:
      url: '$REGISTRY_URL'
      authentication:
        mode: basic
        basic:
          username: user
          password: password
      value_schema:
        subject_name: kong-value
        schema_version: latest
        payload_encoding: simple_json
  message_by_lua_functions:
  - return function(message) return message.body end
plugin: kafka-upstream
" | kubectl apply -f -

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Prerequisite: Configure your Personal Access Token

terraform {
  required_providers {
    konnect = {
      source  = "kong/konnect"
    }
  }
}

provider "konnect" {
  personal_access_token = "$KONNECT_TOKEN"
  server_url            = "https://us.api.konghq.com/"
}

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Add the following to your Terraform configuration to create a Konnect Gateway Plugin:

resource "konnect_gateway_plugin_kafka_upstream" "my_kafka_upstream" {
  enabled = true

  config = {
    bootstrap_servers = [
      {
        host = var.bootstrap_server_host
        port = 9092
      }    ]
    topic = var.kafka_topic

    schema_registry = {

      confluent = {
        url = var.registry_url

        authentication = {
          mode = "basic"

          basic = {
            username = "user"
            password = "password"
          }
        }

        value_schema = {
          subject_name = "kong-value"
          schema_version = "latest"
          payload_encoding = "simple_json"
        }
      }
    }
    message_by_lua_functions = ["return function(message) return message.body end"]
  }

  control_plane_id = konnect_gateway_control_plane.my_konnect_cp.id
}

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This example requires the following variables to be added to your manifest. You can specify values at runtime by setting TF_VAR_name=value.

variable "kafka_topic" {
  type = string
}
variable "bootstrap_server_host" {
  type = string
}
variable "registry_url" {
  type = string
}

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Add this section to your kong.yaml configuration file:

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kong.yaml

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_format_version: "3.0"
plugins:
  - name: kafka-upstream
    service: serviceName|Id
    config:
      bootstrap_servers:
      - host: ${{ env "DECK_BOOTSTRAP_SERVER_HOST" }}
        port: 9092
      topic: ${{ env "DECK_KAFKA_TOPIC" }}
      schema_registry:
        confluent:
          url: ${{ env "DECK_REGISTRY_URL" }}
          authentication:
            mode: basic
            basic:
              username: user
              password: password
          value_schema:
            subject_name: kong-value
            schema_version: latest
            payload_encoding: simple_json
      message_by_lua_functions:
      - return function(message) return message.body end

Make sure to replace the following placeholders with your own values:

serviceName|Id: The id or name of the service the plugin configuration will target.

Make the following request:

curl -i -X POST http://localhost:8001/services/{serviceName|Id}/plugins/ \
    --header "Accept: application/json" \
    --header "Content-Type: application/json" \
    --data '
    {
      "name": "kafka-upstream",
      "config": {
        "bootstrap_servers": [
          {
            "host": "'$BOOTSTRAP_SERVER_HOST'",
            "port": 9092
          }
        ],
        "topic": "'$KAFKA_TOPIC'",
        "schema_registry": {
          "confluent": {
            "url": "'$REGISTRY_URL'",
            "authentication": {
              "mode": "basic",
              "basic": {
                "username": "user",
                "password": "password"
              }
            },
            "value_schema": {
              "subject_name": "kong-value",
              "schema_version": "latest",
              "payload_encoding": "simple_json"
            }
          }
        },
        "message_by_lua_functions": [
          "return function(message) return message.body end"
        ]
      }
    }
    '

Copied!

Make sure to replace the following placeholders with your own values:

serviceName|Id: The id or name of the service the plugin configuration will target.

Make the following request:

curl -X POST https://{region}.api.konghq.com/v2/control-planes/{controlPlaneId}/core-entities/services/{serviceId}/plugins/ \
    --header "accept: application/json" \
    --header "Content-Type: application/json" \
    --header "Authorization: Bearer $KONNECT_TOKEN" \
    --data '
    {
      "name": "kafka-upstream",
      "config": {
        "bootstrap_servers": [
          {
            "host": "'$BOOTSTRAP_SERVER_HOST'",
            "port": 9092
          }
        ],
        "topic": "'$KAFKA_TOPIC'",
        "schema_registry": {
          "confluent": {
            "url": "'$REGISTRY_URL'",
            "authentication": {
              "mode": "basic",
              "basic": {
                "username": "user",
                "password": "password"
              }
            },
            "value_schema": {
              "subject_name": "kong-value",
              "schema_version": "latest",
              "payload_encoding": "simple_json"
            }
          }
        },
        "message_by_lua_functions": [
          "return function(message) return message.body end"
        ]
      }
    }
    '

Copied!

Make sure to replace the following placeholders with your own values:

region: Geographic region where your Kong Konnect is hosted and operates.
KONNECT_TOKEN: Your Personal Access Token (PAT) associated with your Konnect account.
controlPlaneId: The id of the control plane.
serviceId: The id of the service the plugin configuration will target.

See the Konnect Control Planes Config API reference to learn about region-specific URLs and personal access tokens.

echo "
apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: kafka-upstream
  namespace: kong
  annotations:
    kubernetes.io/ingress.class: kong
config:
  bootstrap_servers:
  - host: '$BOOTSTRAP_SERVER_HOST'
    port: 9092
  topic: '$KAFKA_TOPIC'
  schema_registry:
    confluent:
      url: '$REGISTRY_URL'
      authentication:
        mode: basic
        basic:
          username: user
          password: password
      value_schema:
        subject_name: kong-value
        schema_version: latest
        payload_encoding: simple_json
  message_by_lua_functions:
  - return function(message) return message.body end
plugin: kafka-upstream
" | kubectl apply -f -

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Next, apply the KongPlugin resource by annotating the service resource:

kubectl annotate -n kong service SERVICE_NAME konghq.com/plugins=kafka-upstream

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Prerequisite: Configure your Personal Access Token

terraform {
  required_providers {
    konnect = {
      source  = "kong/konnect"
    }
  }
}

provider "konnect" {
  personal_access_token = "$KONNECT_TOKEN"
  server_url            = "https://us.api.konghq.com/"
}

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Add the following to your Terraform configuration to create a Konnect Gateway Plugin:

resource "konnect_gateway_plugin_kafka_upstream" "my_kafka_upstream" {
  enabled = true

  config = {
    bootstrap_servers = [
      {
        host = var.bootstrap_server_host
        port = 9092
      }    ]
    topic = var.kafka_topic

    schema_registry = {

      confluent = {
        url = var.registry_url

        authentication = {
          mode = "basic"

          basic = {
            username = "user"
            password = "password"
          }
        }

        value_schema = {
          subject_name = "kong-value"
          schema_version = "latest"
          payload_encoding = "simple_json"
        }
      }
    }
    message_by_lua_functions = ["return function(message) return message.body end"]
  }

  control_plane_id = konnect_gateway_control_plane.my_konnect_cp.id
  service = {
    id = konnect_gateway_service.my_service.id
  }
}

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This example requires the following variables to be added to your manifest. You can specify values at runtime by setting TF_VAR_name=value.

variable "kafka_topic" {
  type = string
}
variable "bootstrap_server_host" {
  type = string
}
variable "registry_url" {
  type = string
}

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Add this section to your kong.yaml configuration file:

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kong.yaml

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_format_version: "3.0"
plugins:
  - name: kafka-upstream
    route: routeName|Id
    config:
      bootstrap_servers:
      - host: ${{ env "DECK_BOOTSTRAP_SERVER_HOST" }}
        port: 9092
      topic: ${{ env "DECK_KAFKA_TOPIC" }}
      schema_registry:
        confluent:
          url: ${{ env "DECK_REGISTRY_URL" }}
          authentication:
            mode: basic
            basic:
              username: user
              password: password
          value_schema:
            subject_name: kong-value
            schema_version: latest
            payload_encoding: simple_json
      message_by_lua_functions:
      - return function(message) return message.body end

Make sure to replace the following placeholders with your own values:

routeName|Id: The id or name of the route the plugin configuration will target.

Make the following request:

curl -i -X POST http://localhost:8001/routes/{routeName|Id}/plugins/ \
    --header "Accept: application/json" \
    --header "Content-Type: application/json" \
    --data '
    {
      "name": "kafka-upstream",
      "config": {
        "bootstrap_servers": [
          {
            "host": "'$BOOTSTRAP_SERVER_HOST'",
            "port": 9092
          }
        ],
        "topic": "'$KAFKA_TOPIC'",
        "schema_registry": {
          "confluent": {
            "url": "'$REGISTRY_URL'",
            "authentication": {
              "mode": "basic",
              "basic": {
                "username": "user",
                "password": "password"
              }
            },
            "value_schema": {
              "subject_name": "kong-value",
              "schema_version": "latest",
              "payload_encoding": "simple_json"
            }
          }
        },
        "message_by_lua_functions": [
          "return function(message) return message.body end"
        ]
      }
    }
    '

Copied!

Make sure to replace the following placeholders with your own values:

routeName|Id: The id or name of the route the plugin configuration will target.

Make the following request:

curl -X POST https://{region}.api.konghq.com/v2/control-planes/{controlPlaneId}/core-entities/routes/{routeId}/plugins/ \
    --header "accept: application/json" \
    --header "Content-Type: application/json" \
    --header "Authorization: Bearer $KONNECT_TOKEN" \
    --data '
    {
      "name": "kafka-upstream",
      "config": {
        "bootstrap_servers": [
          {
            "host": "'$BOOTSTRAP_SERVER_HOST'",
            "port": 9092
          }
        ],
        "topic": "'$KAFKA_TOPIC'",
        "schema_registry": {
          "confluent": {
            "url": "'$REGISTRY_URL'",
            "authentication": {
              "mode": "basic",
              "basic": {
                "username": "user",
                "password": "password"
              }
            },
            "value_schema": {
              "subject_name": "kong-value",
              "schema_version": "latest",
              "payload_encoding": "simple_json"
            }
          }
        },
        "message_by_lua_functions": [
          "return function(message) return message.body end"
        ]
      }
    }
    '

Copied!

Make sure to replace the following placeholders with your own values:

region: Geographic region where your Kong Konnect is hosted and operates.
KONNECT_TOKEN: Your Personal Access Token (PAT) associated with your Konnect account.
controlPlaneId: The id of the control plane.
routeId: The id of the route the plugin configuration will target.

See the Konnect Control Planes Config API reference to learn about region-specific URLs and personal access tokens.

echo "
apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: kafka-upstream
  namespace: kong
  annotations:
    kubernetes.io/ingress.class: kong
config:
  bootstrap_servers:
  - host: '$BOOTSTRAP_SERVER_HOST'
    port: 9092
  topic: '$KAFKA_TOPIC'
  schema_registry:
    confluent:
      url: '$REGISTRY_URL'
      authentication:
        mode: basic
        basic:
          username: user
          password: password
      value_schema:
        subject_name: kong-value
        schema_version: latest
        payload_encoding: simple_json
  message_by_lua_functions:
  - return function(message) return message.body end
plugin: kafka-upstream
" | kubectl apply -f -

Copied!

Next, apply the KongPlugin resource by annotating the httproute or ingress resource:

kubectl annotate -n kong httproute  konghq.com/plugins=kafka-upstream

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kubectl annotate -n kong ingress  konghq.com/plugins=kafka-upstream

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Prerequisite: Configure your Personal Access Token

terraform {
  required_providers {
    konnect = {
      source  = "kong/konnect"
    }
  }
}

provider "konnect" {
  personal_access_token = "$KONNECT_TOKEN"
  server_url            = "https://us.api.konghq.com/"
}

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Add the following to your Terraform configuration to create a Konnect Gateway Plugin:

resource "konnect_gateway_plugin_kafka_upstream" "my_kafka_upstream" {
  enabled = true

  config = {
    bootstrap_servers = [
      {
        host = var.bootstrap_server_host
        port = 9092
      }    ]
    topic = var.kafka_topic

    schema_registry = {

      confluent = {
        url = var.registry_url

        authentication = {
          mode = "basic"

          basic = {
            username = "user"
            password = "password"
          }
        }

        value_schema = {
          subject_name = "kong-value"
          schema_version = "latest"
          payload_encoding = "simple_json"
        }
      }
    }
    message_by_lua_functions = ["return function(message) return message.body end"]
  }

  control_plane_id = konnect_gateway_control_plane.my_konnect_cp.id
  route = {
    id = konnect_gateway_route.my_route.id
  }
}

Copied!

This example requires the following variables to be added to your manifest. You can specify values at runtime by setting TF_VAR_name=value.

variable "kafka_topic" {
  type = string
}
variable "bootstrap_server_host" {
  type = string
}
variable "registry_url" {
  type = string
}

Copied!

Add this section to your kong.yaml configuration file:

decK

kong.yaml

Copied!

_format_version: "3.0"
plugins:
  - name: kafka-upstream
    consumer: consumerName|Id
    config:
      bootstrap_servers:
      - host: ${{ env "DECK_BOOTSTRAP_SERVER_HOST" }}
        port: 9092
      topic: ${{ env "DECK_KAFKA_TOPIC" }}
      schema_registry:
        confluent:
          url: ${{ env "DECK_REGISTRY_URL" }}
          authentication:
            mode: basic
            basic:
              username: user
              password: password
          value_schema:
            subject_name: kong-value
            schema_version: latest
            payload_encoding: simple_json
      message_by_lua_functions:
      - return function(message) return message.body end

Make sure to replace the following placeholders with your own values:

consumerName|Id: The id or name of the consumer the plugin configuration will target.

Make the following request:

curl -i -X POST http://localhost:8001/consumers/{consumerName|Id}/plugins/ \
    --header "Accept: application/json" \
    --header "Content-Type: application/json" \
    --data '
    {
      "name": "kafka-upstream",
      "config": {
        "bootstrap_servers": [
          {
            "host": "'$BOOTSTRAP_SERVER_HOST'",
            "port": 9092
          }
        ],
        "topic": "'$KAFKA_TOPIC'",
        "schema_registry": {
          "confluent": {
            "url": "'$REGISTRY_URL'",
            "authentication": {
              "mode": "basic",
              "basic": {
                "username": "user",
                "password": "password"
              }
            },
            "value_schema": {
              "subject_name": "kong-value",
              "schema_version": "latest",
              "payload_encoding": "simple_json"
            }
          }
        },
        "message_by_lua_functions": [
          "return function(message) return message.body end"
        ]
      }
    }
    '

Copied!

Make sure to replace the following placeholders with your own values:

consumerName|Id: The id or name of the consumer the plugin configuration will target.

Make the following request:

curl -X POST https://{region}.api.konghq.com/v2/control-planes/{controlPlaneId}/core-entities/consumers/{consumerId}/plugins/ \
    --header "accept: application/json" \
    --header "Content-Type: application/json" \
    --header "Authorization: Bearer $KONNECT_TOKEN" \
    --data '
    {
      "name": "kafka-upstream",
      "config": {
        "bootstrap_servers": [
          {
            "host": "'$BOOTSTRAP_SERVER_HOST'",
            "port": 9092
          }
        ],
        "topic": "'$KAFKA_TOPIC'",
        "schema_registry": {
          "confluent": {
            "url": "'$REGISTRY_URL'",
            "authentication": {
              "mode": "basic",
              "basic": {
                "username": "user",
                "password": "password"
              }
            },
            "value_schema": {
              "subject_name": "kong-value",
              "schema_version": "latest",
              "payload_encoding": "simple_json"
            }
          }
        },
        "message_by_lua_functions": [
          "return function(message) return message.body end"
        ]
      }
    }
    '

Copied!

Make sure to replace the following placeholders with your own values:

region: Geographic region where your Kong Konnect is hosted and operates.
KONNECT_TOKEN: Your Personal Access Token (PAT) associated with your Konnect account.
controlPlaneId: The id of the control plane.
consumerId: The id of the consumer the plugin configuration will target.

See the Konnect Control Planes Config API reference to learn about region-specific URLs and personal access tokens.

echo "
apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: kafka-upstream
  namespace: kong
  annotations:
    kubernetes.io/ingress.class: kong
config:
  bootstrap_servers:
  - host: '$BOOTSTRAP_SERVER_HOST'
    port: 9092
  topic: '$KAFKA_TOPIC'
  schema_registry:
    confluent:
      url: '$REGISTRY_URL'
      authentication:
        mode: basic
        basic:
          username: user
          password: password
      value_schema:
        subject_name: kong-value
        schema_version: latest
        payload_encoding: simple_json
  message_by_lua_functions:
  - return function(message) return message.body end
plugin: kafka-upstream
" | kubectl apply -f -

Copied!

Next, apply the KongPlugin resource by annotating the KongConsumer resource:

kubectl annotate -n kong kongconsumer CONSUMER_NAME konghq.com/plugins=kafka-upstream

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Prerequisite: Configure your Personal Access Token

terraform {
  required_providers {
    konnect = {
      source  = "kong/konnect"
    }
  }
}

provider "konnect" {
  personal_access_token = "$KONNECT_TOKEN"
  server_url            = "https://us.api.konghq.com/"
}

Copied!

Add the following to your Terraform configuration to create a Konnect Gateway Plugin:

resource "konnect_gateway_plugin_kafka_upstream" "my_kafka_upstream" {
  enabled = true

  config = {
    bootstrap_servers = [
      {
        host = var.bootstrap_server_host
        port = 9092
      }    ]
    topic = var.kafka_topic

    schema_registry = {

      confluent = {
        url = var.registry_url

        authentication = {
          mode = "basic"

          basic = {
            username = "user"
            password = "password"
          }
        }

        value_schema = {
          subject_name = "kong-value"
          schema_version = "latest"
          payload_encoding = "simple_json"
        }
      }
    }
    message_by_lua_functions = ["return function(message) return message.body end"]
  }

  control_plane_id = konnect_gateway_control_plane.my_konnect_cp.id
  consumer = {
    id = konnect_gateway_consumer.my_consumer.id
  }
}

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This example requires the following variables to be added to your manifest. You can specify values at runtime by setting TF_VAR_name=value.

variable "kafka_topic" {
  type = string
}
variable "bootstrap_server_host" {
  type = string
}
variable "registry_url" {
  type = string
}

Copied!

Kafka Upstream

Simple JSON encoding for Avro schemasv3.16+

Prerequisites

Environment variables

Set up the plugin

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