Delivering data from an Apache Kafka® queue to ClickHouse®

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Updated at January 15, 2026

Getting started
Send test data to the Managed Service for Apache Kafka® topic
Set up and activate the transfer
Test the transfer
Delete the resources you created

A Managed Service for ClickHouse® cluster can ingest data from Apache Kafka® topics in real time. This data will be automatically inserted into ClickHouse® Kafka-engine tables.

To set up data delivery from Managed Service for Apache Kafka® to Managed Service for ClickHouse®:

If you no longer need the resources you created, delete them.

Getting started

Required paid resources

Managed Service for Apache Kafka® cluster: Computing resources allocated to hosts, storage and backup size (see Managed Service for Apache Kafka® pricing).
Managed Service for ClickHouse® cluster: Computing resources allocated to hosts, storage and backup size (see Managed Service for ClickHouse® pricing).
Public IP addresses if public access is enabled for cluster hosts (see Virtual Private Cloud pricing).

Set up your infrastructure

Manually

Terraform

Create a Managed Service for Apache Kafka® source cluster in any suitable configuration. Enable public access to the cluster during creation so you can connect to it from your local machine. Connections from within the Yandex Cloud network are enabled by default.
Create a topic in the Managed Service for Apache Kafka® cluster.
Create users so that the producer and consumer can access the topic in the Managed Service for Apache Kafka® cluster:
- With the ACCESS_ROLE_PRODUCER role for the producer.
- With the ACCESS_ROLE_CONSUMER role for the consumer.
Create a Managed Service for ClickHouse® target cluster in any suitable configuration. Enable public access to the cluster during creation so you can connect to it from your local machine. Connections from within the Yandex Cloud network are enabled by default.
If using security groups, configure them to allow internet access to your clusters:
- Managed Service for Apache Kafka®.
- Managed Service for ClickHouse®.

If you do not have Terraform yet, install it.
Get the authentication credentials. You can add them to environment variables or specify them later in the provider configuration file.
Configure and initialize a provider. There is no need to create a provider configuration file manually, you can download it.
Place the configuration file in a separate working directory and specify the parameter values. If you did not add the authentication credentials to environment variables, specify them in the configuration file.
Download the data-transfer-mkf-mch.tf configuration file to the same working directory.

This file describes:
- Network.
- Subnet.
- security group and rules required to connect to the clusters from the internet.
- Managed Service for Apache Kafka® source cluster.
- Topic and two Apache Kafka® users on whose behalf the producer and consumer will connect to the topic.
- Managed Service for ClickHouse® target cluster.
- Target endpoint.
- Transfer.
In the data-transfer-mkf-mch.tf file, specify the following:
- Managed Service for Apache Kafka® source cluster parameters:
  - source_user_producer and source_password_producer: Producer's username and password.
  - source_user_consumer and source_password_consumer: Consumer's username and password.
  - source_topic_name: Topic name.
- The Managed Service for ClickHouse® target cluster parameters that will be used as the target endpoint parameters:
  - target_db_name: Managed Service for ClickHouse® database name.
  - target_user and target_password: Database owner username and password.
Validate your Terraform configuration files using this command:
```
terraform validate
```
Terraform will display any configuration errors detected in your files.
Create the required infrastructure:
1. Run this command to view the planned changes:
```
terraform plan
```
  If you described the configuration correctly, the terminal will display a list of the resources to update and their parameters. This is a verification step that does not apply changes to your resources.
2. If everything looks correct, apply the changes:
  1. Run this command:
```
terraform apply
```
  2. Confirm updating the resources.
  3. Wait for the operation to complete.
All the required resources will be created in the specified folder. You can check resource availability and their settings in the management console.

Configure additional settings

Install the following tools:

kafkacat: To read and write data to the Apache Kafka® topic.
```
sudo apt update && sudo apt install --yes kafkacat
```
Verify that you can use it to establish SSL connections to your Managed Service for Apache Kafka® clusters.

clickhouse-client: For connecting to a database within the Managed Service for ClickHouse® cluster.

Add the ClickHouse® DEB repository:

sudo apt update && sudo apt install --yes apt-transport-https ca-certificates dirmngr && \
sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv E0C56BD4 && \
echo "deb https://packages.clickhouse.com/deb stable main" | sudo tee \
/etc/apt/sources.list.d/clickhouse.list

Install the dependencies:

sudo apt update && sudo apt install --yes clickhouse-client

Download the clickhouse-client configuration file:

mkdir -p ~/.clickhouse-client && \
wget "https://storage.yandexcloud.net/doc-files/clickhouse-client.conf.example" \
  --output-document ~/.clickhouse-client/config.xml

Verify that you can establish an SSL connection to the Managed Service for ClickHouse® cluster via clickhouse-client.

jq: For stream processing of JSON files.

sudo apt update && sudo apt-get install --yes jq

Send test data to the Managed Service for Apache Kafka® topic

Suppose that your Apache Kafka® topic receives data from car sensors. This data will be transmitted as Apache Kafka® messages in JSON format:

{
    "device_id":"iv9a94th6rzt********",
    "datetime":"2020-06-05 17:27:00",
    "latitude":"55.70329032",
    "longitude":"37.65472196",
    "altitude":"427.5",
    "speed":"0",
    "battery_voltage":"23.5",
    "cabin_temperature":"17",
    "fuel_level":null
}

The Managed Service for ClickHouse® cluster will use JSONEachRow data format to insert data into Kafka tables. This format converts strings from Apache Kafka® messages to relevant column values.

Create a sample.json file with test data:

sample.json

{
    "device_id": "iv9a94th6rzt********",
    "datetime": "2020-06-05 17:27:00",
    "latitude": 55.70329032,
    "longitude": 37.65472196,
    "altitude": 427.5,
    "speed": 0,
    "battery_voltage": 23.5,
    "cabin_temperature": 17,
    "fuel_level": null
}

{
    "device_id": "rhibbh3y08qm********",
    "datetime": "2020-06-06 09:49:54",
    "latitude": 55.71294467,
    "longitude": 37.66542005,
    "altitude": 429.13,
    "speed": 55.5,
    "battery_voltage": null,
    "cabin_temperature": 18,
    "fuel_level": 32
}

{
    "device_id": "iv9a94th6rzt********",
    "datetime": "2020-06-07 15:00:10",
    "latitude": 55.70985913,
    "longitude": 37.62141918,
    "altitude": 417.0,
    "speed": 15.7,
    "battery_voltage": 10.3,
    "cabin_temperature": 17,
    "fuel_level": null
}

Send data from the sample.json file to the Managed Service for Apache Kafka® topic using jq and kafkacat:

jq -rc . sample.json | kafkacat -P \
   -b <broker_host_FQDN>:9091 \
   -t <topic_name> \
   -k key \
   -X security.protocol=SASL_SSL \
   -X sasl.mechanisms=SCRAM-SHA-512 \
   -X sasl.username="<username_for_producer>" \
   -X sasl.password="<user_password_for_producer>" \
   -X ssl.ca.location=/usr/local/share/ca-certificates/Yandex/RootCA.crt -Z

Set up and activate the transfer

Note

To rapidly deliver a large volume of data, use special endpoint settings.

Create a source endpoint:

Database type: Kafka

Endpoint parameters → Connection settings:

Connection type: Managed Service for Apache Kafka cluster
- Managed Service for Apache Kafka cluster: Select the source cluster from the list.
- Authentication:
  - Username: Enter the consumer username.
  - Password: Enter the consumer password.
Topic full name: Enter the name of the topic in the Managed Service for Apache Kafka® cluster.

Advanced settings → Conversion rules:

Data format: JSON

Data scheme: JSON specification:

Copy and paste the data schema in JSON format:

Data schema

[
    {
        "name": "device_id",
        "type": "string"
    },
    {
        "name": "datetime",
        "type": "datetime"
    },
    {
        "name": "latitude",
        "type": "double"
    },
    {
        "name": "longitude",
        "type": "double"
    },
    {
        "name": "altitude",
        "type": "double"
    },
    {
        "name": "speed",
        "type": "double"
    },
    {
        "name": "battery_voltage",
        "type": "any"
    },
    {
        "name": "cabin_temperature",
        "type": "double"
    },
    {
        "name": "fuel_level",
        "type": "any"
    }
]

Create a target endpoint and transfer:
Manually

Terraform
1. Create a target endpoint:
  - Database type: ClickHouse.
  - Endpoint parameters:
    
    Connection settings:
    
    Connection type: Managed cluster.
    
    Managed cluster: Select the source cluster from the list.
    
    Database: Enter the database name.
    
    User and Password: Enter the name and password of the user who has access to the database, e.g., the database owner.
    
    Advanced settings → Upload data in JSON format: Enable this option if you enabled Conversion rules in the advanced settings of the source endpoint.
2. Create a Replication-type transfer configured to use the new endpoints.
3. Activate the transfer.
1. In the data-transfer-mkf-mch.tf file, uncomment the following:
  - The source_endpoint_id variable and set it to the value of the endpoint ID for the source created in the previous step.
  - yandex_datatransfer_endpoint and yandex_datatransfer_transfer resources.
2. Validate your Terraform configuration files using this command:
  terraform validate
  Terraform will display any configuration errors detected in your files.
3. Create the required infrastructure:
  1. Run this command to view the planned changes:
    
    terraform plan
    
    If you described the configuration correctly, the terminal will display a list of the resources to update and their parameters. This is a verification step that does not apply changes to your resources.
  2. If everything looks correct, apply the changes:
    
    Run this command:
    
    terraform apply
    
    Confirm updating the resources.
    
    Wait for the operation to complete.
  The transfer will activate automatically upon creation.

Test the transfer

Wait for the transfer status to change to Replicating.
Make sure that the data from the source Managed Service for Apache Kafka® cluster has been transferred to the Managed Service for ClickHouse® database:
1. Connect to the cluster using clickhouse-client.
2. Run this query:
```
SELECT * FROM <ClickHouse®_database_name>.<Apache_Kafka_topic_name>
```

Change values in the sample.json file and send data from it to the Managed Service for Apache Kafka® topic:

jq -rc . sample.json | kafkacat -P \
   -b <broker_host_FQDN>:9091 \
   -t <topic_name> \
   -k key \
   -X security.protocol=SASL_SSL \
   -X sasl.mechanisms=SCRAM-SHA-512 \
   -X sasl.username="<username_for_producer>" \
   -X sasl.password="<user_password_for_producer>" \
   -X ssl.ca.location=/usr/local/share/ca-certificates/Yandex/RootCA.crt -Z

Make sure that the new values are now in the Managed Service for ClickHouse® database:
1. Connect to the cluster via clickhouse-client.
2. Run this query:
```
SELECT * FROM <ClickHouse®_database_name>.<Apache_Kafka_topic_name>
```

Delete the resources you created

Note

Before deleting the resources, deactivate the transfer.

To reduce the consumption of resources you do not need, delete them:

Delete the transfer.
Delete the source endpoint.
Delete other resources using the same method used for their creation:
Manually

Terraform
1. In the terminal window, go to the directory containing the infrastructure plan.
  
  Warning
  
  Make sure the directory has no Terraform manifests with the resources you want to keep. Terraform deletes all resources that were created using the manifests in the current directory.
2. Delete resources:
  1. Run this command:
    
    terraform destroy
  2. Confirm deleting the resources and wait for the operation to complete.
  All the resources described in the Terraform manifests will be deleted.

ClickHouse® is a registered trademark of ClickHouse, Inc.

Delivering data from an Apache Kafka® queue to ClickHouse®

Getting startedGetting started

Required paid resourcesRequired paid resources

Set up your infrastructureSet up your infrastructure

Configure additional settingsConfigure additional settings

Send test data to the Managed Service for Apache Kafka® topicSend test data to the Managed Service for Apache Kafka® topic

Set up and activate the transferSet up and activate the transfer

Test the transferTest the transfer

Delete the resources you createdDelete the resources you created

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