Apache Kafka® with MongoDB source connector#

The Aiven Terraform Provider is a great choice for provisioning an Aiven for Apache Kafka® cluster with Kafka Connect enabled and the MongoDB source connector configured.

Let’s check out the following diagram to understand the setup.

flowchart LR id1[(MongoDB Database)] subgraph Kafka Connect MongoDB-Source-Connector end subgraph Apache Kafka Topic end id1 --->|polls changes| MongoDB-Source-Connector -->|publishes changes| Topic

Describe the setup#

Here is the Terraform recipe that will spin up an Aiven for Apache Kafka service with Kafka Connect enabled. This recipe will also create and configure a MongoDB source connector.

Warning

Aiven provides the option to run Kafka Connect on the same nodes as your Kafka cluster, sharing the resources. This is a low-cost way to get started with Kafka Connect. A standalone Aiven for Apache Kafka® Connect allows you to scale independently, offers more CPU time and memory for the Kafka Connect service and reduces load on nodes, making the cluster more stable.

Before you begin, you will require a MongoDB database and the related database connection information. You’ll also need to make sure that the database is reachable from the public internet (unless it’s part of a paired VPC).

Tip

Be sure to check out the getting started guide to learn about the common files required to execute the following recipe. For example, you’ll need to declare the variables for project_name, api_token, service_name_prefix, and mongodb_connection_uri.

services.tf file:

resource "aiven_kafka" "demo-kafka" {
  project                 = var.project_name
  cloud_name              = "google-northamerica-northeast1"
  plan                    = "business-4"
  service_name            = join("-", [var.service_name_prefix, "kafka"])
  maintenance_window_dow  = "sunday"
  maintenance_window_time = "10:00:00"
  kafka_user_config {
    kafka_connect = true
    kafka_rest    = true
    kafka_version = "3.1"
    kafka {
      auto_create_topics_enable    = true
    }
  }
}

resource "aiven_kafka_connector" "mongodb-source-connector" {
  project        = var.project_name
  service_name   = aiven_kafka.demo-kafka.service_name
  connector_name = "mongodb-source-connector"
  config = {
    "name" : "mongodb-source-connector"
    "connector.class" : "com.mongodb.kafka.connect.MongoSourceConnector"
    "connection.uri" = var.mongodb_connection_uri
    "database" : "sample_airbnb"
    "collection" : "listingsAndReviews"
    "copy.existing" : "true"
    "poll.await.time.ms" : "1000"
    "output.format.value" : "json"
    "output.format.key" : "json"
    "publish.full.document.only" : "true"
  }
}
  • Since you have kafka_connect set to true under the kafka_user_config, you don’t need a standalone Aiven for Apache Kafka Connect service.

  • The auto_create_topics_enable flag is enabled, therefore the connector is able to create the topic on the Apache Kafka cluster by pushing the first message, without having to create the topic first.

  • The automatically created topic name will be the concatenation of database and collection parameters - sample_airbnb.listingsAndReviews in this example.

  • poll.await.time.ms can be configured to set the amount of wait time before the MongoDB source connector pulls the new changes from a collection.

  • publish.full.document.only, when set to true, only publishes the actual document rather than the full change stream document. The default value of the parameter is false.

More resources#

Keep in mind that some parameters and configurations will vary for your case. A reference to some of the advanced Apache Kafka configurations and other related resources: