This repo contains a demo Flask app using Apache Kafka® as backend. It provides examples of:

• Apache Kafka producer and consumer
• Topic partitions and parallel consumers
• Consumer Group
• Kafka Connect sink to OpenSearch

The default code uses Aiven for Apache Kafka® and Aiven for OpenSearch, but can work with any Apache Kafka® and OpenSearch environments by changing the HOST and PORT parameters. If you want to give a try to Aiven for Apache Kafka, you can sign-up for our trial.

An overview of the flask app is provided in the above diagram

The Flask app contains the following endpoints:

• /: to view the list of pizza options and place an order in the pizza-orders topic
• /pizza-makers: to view the pizza-orders topic data and act as a "pizzaiolo" making a pizza and sending it to delivery (pizza-delivery topic). The example supports up to 2 parallel pizza-makers sessions, if more than one is open each of the sessions will show up only data coming from a single Kafka topic partition
• /pizza-ready/<id>: when a pizza is ready, the pizzaiolo will be able to click the related button in /pizza-makers page and the order will be added to the pizza-delivery topic by calling this endpoint
• /pizza-calc: to view the pizza-orders topic data as a billing person. This consumer is associated to a different consumer group compared to pizza-makers so both will receive the same order
• /pizza-delivery: to view the pizza-delivery topic data.

1. Create a virtual environment

   python3 -m venv kafka-flask
   source kafka-flask/bin/activate
   

2. Install the required dependencies

   pip install -r requirements.txt
   

3. Copy the env.conf.example to env.conf and customize the parameters for TOKEN and PROJECT_NAME

4. Create Aiven for Apache Kafka (requires jq to be installed)

   code/start-services.sh
   

   This code will create:

   • An Aiven for Apache Kafka service named demo-kafka in the project passed as parameter
   • A local folder called certs containing the required SSL certificate files required for the connection
   • An environment file code/kafka-endpoint-conf.py containing the Aiven for Apache Kafka service endpoints
   • An Aiven for Opensearch service named demo-opensearch in the project passed as parameter
   • An Kafka Connect configuration file code/opensearch_sink.json allowing to sink the pizza-orders data into an OpenSearch Index

5. To start the flask app execute

   python code/app.py
   

6. Open the following windows in a browser to check the various endpoints

   • http://127.0.0.1:5000/: to view the list of pizza options and place an order in the pizza-orders topic
   • http://127.0.0.1:5000/pizza-makers: to view the pizza-orders topic data and act as a "pizzaiolo" making a pizza and sending it to delivery (pizza-delivery topic). The example supports up to 2 parallel pizza-makers sessions, if more than one is open each of the sessions will show up only data coming from a single Kafka topic partition
   • http://127.0.0.1:5000/pizza-calc: to view the pizza-orders topic data as a billing person. This consumer is associated to a different consumer group compared to pizza-makers so both will receive the same order
   • http://127.0.0.1:5000/pizza-delivery: to view the pizza-delivery topic data.

7. Optionally, execute the following code to start the Kafka Connect connector to sink the pizza-orders topic data to Opensearch

   avn service connector create demo-flask-kafka @code/opensearch_sink.json
   

8. To delete all services run

   code/delete-services.sh
   

Apache Kafka® on Flask is licensed under the Apache license, version 2.0. Full license text is available in the LICENSE file.

Please note that the project explicitly does not require a CLA (Contributor License Agreement) from its contributors.

Bug reports and patches are very welcome, please post them as GitHub issues and pull requests at https://github.com/ftisiot/flask-apache-kafka-demo. To report any possible vulnerabilities or other serious issues please see our security policy.