User geolocation app

This app uses the free IPStack API to get a user geolocation through their IP address.

How it works

1. The app subscribe to a input kafka topic
2. From this topic the application receives user ID and IP, so this IP is submitted to IPStack which returns the geolocation data
3. The primary user information is added to this new data and the full user information is then sended to a output kafka topic

Each time a new IP comes from "input" topic, its information is also kept in a Redis cache, which stores the data for a given time period. If a cached IP arrives from "input", the cache is retrieved and no IPStack request will be made, neither a new message is sent to "output". As soon as the cache expires the regular behavior is re-established.

Running

The app runs with Docker. All the necessary dependencies as well the application can be runned through docker-compose with the following command:

docker-compose up

Running in development and testing

To run only the app dependencies use the command:

docker-compose -f docker-compose-infra.yaml up

Make sure there's only one container instance per dependency to avoid errors. Before each set up call:

docker-compose down

It's possible run the app in development mode with:

npm run start:dev

And it's possible to execute the Jest tests with

npm test

Both the commands can be runned directly in the host machine, where Node version 16 or higher is necessary.

Optionally a docker container can be used as well. For this, enter the command:

docker run --rm -it --volume $(pwd):/usr/app --workdir /usr/app --network="host" node:18.1-alpine sh

This command will run a Node image in the same version of production using the host machine network interface. Inside the container terminal, just use the presented development and test commands.

Manual test

If you want to do a manual test, once kafka is initialized, you can send a message to the input topic using the kafka docker image:

1. Run docker run -it --network="host" confluentinc/cp-kafka:latest bash to get a terminal in container
2. Enter kafka-console-producer --broker-list localhost:9094 --topic input to produce at input topic
3. Enter a message like {"clientID":"1","timestamp":0,"ip":"179.179.133.165"}

Environment and execution

Some app configurations (like IPStack API key), are made by environment variables using .env files. The production execution uses the .env file, while development uses .env.development file and test uses .env.test file. Once development and test executions are generally made outside the docker-compose network, it"s necessary to use the external interfaces of the services. Only the .env.sample file must be renamed to .env, and only API_KEY must be necessarily changed for a real key considering the given env.sample to run the app.

Kafka Control Center

To inspect the kafka cluster and the topics, a Kafka Control Center instance is provided in the docker-compose files. To access it, just go to localhost:9021