Get started with Kafka
Stream Postgres changes to a Kafka topic
In this quickstart, you’ll create a real-time data pipeline that streams changes from a Postgres database to a Kafka topic. You’ll:
- Boot Sequin
- Connect to a sample playground database
- Configure a Kafka topic to receive database changes
- See your changes flow in real-time
By the end, you’ll have hands-on experience setting up Postgres change data capture (CDC) with Sequin. This same pattern can be used to setup your own Postgres CDC pipeline with Kafka.
Boot Kafka (optional)
If you don’t already have Kafka running, start Kafka with Docker Compose:
- Download our Docker compose file for Kafka (right click, save link as…).
- Move it to a new directory, navigate to that directory, and start the services:
If you’re using another Kafka instance, ensure you have the connection details ready.
Run Sequin
The easiest way to get started with Sequin is with our Docker Compose file. This file starts a Postgres database, Redis instance, and Sequin server.
Create directory and start services
- Download sequin-docker-compose.zip.
- Unzip the file.
- Navigate to the unzipped directory and start the services:
Verify services are running
Check that Sequin is running using docker ps
:
You should see output like the following:
All three containers should be up and running (status: Up
).
Login
The Docker Compose file automatically configures Sequin with an admin user and a playground database.
Let’s log in to the Sequin web console:
Open the web console
After starting the Docker Compose services, open the Sequin web console at http://localhost:7376:
Login with default credentials
Use the following default credentials to login:
- Email:
- Password:
View the playground database
To get you started quickly, Sequin’s Docker Compose file creates a logical database called sequin_playground
with a sample dataset in the public.products
table.
Let’s take a look:
Navigate to Databases
In the Sequin web console, click Databases in the sidebar.
Select playground database
Click on the pre-configured sequin-playground
database:
The database “Health” should be green.
View contents of the products table
Let’s get a sense of what’s in the products
table. Run the following command:
This command connects to the running Postgres container and runs a psql
command.
You should see a list of the rows in the products
table:
We’ll make modifications to this table in a bit.
Create a Kafka Sink
With the playground database connected, you can create a sink. This sink will send changes to the products
table to your Kafka topic:
Navigate to Sinks
Click “Sinks” in the sidebar navigation, then click “Create Sink”.
Select sink type
Select “Kafka” as the sink type and click “Continue”.
Note "Source" configuration
In the “Source” card, note that the sequin-playground
database and products
table are pre-selected. Leave these defaults:
Setup a backfill
In the “Initial backfill” card, click the toggle to enable an initial backfill. You can leave the default start position, which will backfill all existing rows in the products
table:
Configure "Kafka Configuration"
In the “Kafka Configuration” card, enter your Kafka connection details:
- Hosts: If running locally with the provided docker-compose, use
host.docker.internal:9092
- Topic: The Kafka topic to stream to (e.g.,
products
) - SASL Mechanism: Select if your Kafka cluster requires authentication
- Username/Password: Required if SASL is enabled
- TLS: Toggle on if your Kafka cluster requires TLS
Test the connection
At the bottom of the form, click the “Test Connection” button. If you provided proper credentials, it should succeed.
Sequin can connect to your Kafka cluster.
Create the sink
You can leave the rest of the defaults. As configured, the Kafka topic will first receive a backfill of all rows currently in the products
table. Then, it will receive all changes to the products
table in real-time.
Click “Create Sink” to finish setting up your Kafka sink.
See changes flow to your Kafka topic
On the new sink’s overview page, you should see the “Health” status turn green, indicating data is flowing to your Kafka topic.
Let’s confirm messages are flowing:
Messages tab
Click the “Messages” tab. You’ll see a list of the recently delivered messages:
Sequin indicates it backfilled the products
table to your Kafka topic.
View in Kafka CLI
In your terminal, run the following command to read from the topic:
You should see the messages that were sent from Sequin. These are read
events from the initial backfill of the products
table.
Messages are flowing from Sequin to your Kafka topic.
Make some changes
Let’s make some changes to the products
table and see them flow to your topic.
In your terminal, run the following command to insert a new row into the products
table:
In another terminal, consume messages from your Kafka topic:
You should see a message corresponding to the inserted row.
Feel free to try other changes:
Each change will appear in your Kafka topic within a few seconds.
Great work!
You’ve successfully:
- Set up a complete Postgres change data capture pipeline
- Loaded existing data through a backfill
- Made changes to the
products
table - Verified changes are flowing to your Kafka topic
Ready to stream
Now you’re ready to connect your own database to Sequin and start streaming changes: