Reactive Demo

This repo contains a demo stack for a reactive architecture.

Architecture

Services

./frontend

Description

The front-end is responsible for serving the main web page. It creates a websocket connection back to itself to pass messages. When a user comments, it is emitted over the websocket connection to the app. This app takes this and publishes the comment.received event to the #MessageBus This app listens for comments.updated events and upon receiving one, published a message on the socket so the web page can update itself.

Environment Variables

• PORT set this to the port you want the service to serve from
• RABBITMQ_HOSTNAME the host address of your rabbitmq service

Running

PORT=80 npm start

./parser

Description

The parser is a service which "normalizes" comments. This app listens for comment.received events and upon receiving one it truncates the message to 100 characters and publishes the event comment.normalized with the truncated data. If the comment has the word hate in it, it publishes the event comment.normalize-error.

Environment Variables

• RABBITMQ_HOSTNAME the host address of your rabbitmq service

Running

npm start

./db

Description

The db is a service which saves comments. This app listens for comment.normalized events and upon receiving one it saves the message into the database (currently redis) After saving it publishes comments.updated event with all the comments in the database It also listens for user.connected events and upon receiving one it publishes comments.updated event with all the comments in the database

Environment Variables

• RABBITMQ_HOSTNAME the host address of your rabbitmq service
• REDIS_HOST the host address of your redis service

Running

npm start

./emailer

Description

The emailer is a service which sends emails. This app listens for comment.received events and upon receiving one it it sends an email to the address defined by EMAIL_ADDR

Environment Variables

• RABBITMQ_HOSTNAME the host address of your rabbitmq service
• EMAIL_ADDR the email address to send emails to

Running

npm start

Message bus

The message bus is RabbitMQ

Data Store

The datastore is Redis

Deploying

Compose

There are 3 compose files.

• docker-compose.yml - Use to launch the entire application
• docker-compose-local.yml - Use to launch everything but front-end and rabbit
• docker-compose-remote.yml - Use to launch front-end and rabbit.

I split local and remote because remote should be launched on a server which everyone should have access to and local for services that do not need access.

Kubernetes

The configuration files for Kubernetes live in ./deployments The files at the root of deployments are deploy files and the files in the deployments/services define all the k8 services.

Docker

Every service has a Dockerfile at the root. Simply run docker build . to build docker images. These docker images are also build on docker hub with the following format:

• runnable/reactive-demo:frontend
• runnable/reactive-demo:parser
• runnable/reactive-demo:db
• runnable/reactive-demo:emailer