ponelat / petstore-kafka

A demo site built on top of Kafka topics

Petstore Kafka demo site

This is a contrived demo of a petstore with adoptions. It is build on Kafka topics written in Nodejs.

It exists as a functional example for describing with AsyncAPI.

NOTE: Given the way Kafka rebalances and the need for cacheing, it may take a while (a few minutes) for caches to be built, depending on the size of the Topic.

Architecture

• TODO: Add miro diagram.

• TODO: Add AsyncAPI definition(s)

• There is a browser app (SPA) written in Typescript using Create-React-APP, it's found under [[./web-ui]].

• There is a gateway for serving the SPA and proxying API calls to the other services. It is also under [[./web-ui]] and is a single Caddyfile.

• There is a Pets service (nodejs + kafka sink). [[./services/pets]]

• There is a Adoptions service (nodejs + kafka sink). [[./services/adoptions]]

• There is a Websocket service (nodejs + kafka sink + publishes events). [[./services/websocket]]

• There is a docker-compose file just for Kafka services. [[./services/kafka]].

• There is a docker-compose file for the whole stack, [[./docker-compose.yml]].

Developing

To develop, first make sure you have all the dependencies installed.

WARNING: Kafka needs to know its own hostname. Add an entry to your hosts file mapping kafka.local -> 127.0.0.1. Or tweak the docker-compose file to adjust.

A list can be found by running make dependencies. There are optional dependencie for Tmux/inator, which are helpful for spinning up several servers at once each with their own terminal pane. But that does require a little bit of tmux knowledge.

You can launch each service with make dev-{service} where {service} is the name of the service. A list can be seen by running make help.

Alternatively, if you have Tmuxinator install you can run make dev which will launch all services.

All services have hot-reload, but they make require a restart now and then if there are kafka delays/issues.

Building

All services have a Docker image and the entire stack can be brought up with docker-compose up if the images are built and/or already hosted in hub.docker.com.

To build all images, run make build which will build them one-by-one. All builds happen within the Docker context so it isn't required to run yarn run build beforehand.

Alternatively you can build the indidvidual docker images with make build-{service} where {service} is the service. For a full list see make help.