@peretch/nats-test

Summary

This repository contains an example connecting node applications with a NATS Streaming Server by using node-nats-streaming npm package

Used Technologies

• Skaffold for managing kubernetes and docker images
• NATS Docker Image as NATS Streaming Server
• npm package node-nats-streaming for interacting with NATS Streaming Server.
• Other libraries and types definitions (ts-node-dev, typescript, @types/node)

Terminology

• subject: Is the channel that where we are pushing an event
• channel: Is what we are subscribing to
• subscription: Is what is actually listening to the channel and eventually receive some data

Installation

1. npm install
2. If not isntalled, install skaffold from https://skaffold.dev/docs/install/
3. In one terminal, initialize nats image by using skaffold dev

Usage

Making NATS Service visible

For exposing our NATS Streaming Server, we will make a port forward to the running pod.

1. Check your pod name with command kubectl get pods
2. Copy your running pod name (for example nats-depl-7c95b5f667-zw5cc)
3. Fordward the port 4222 with command kubectl port-forward nats-depl-7c95b5f667-zw5cc 4222:4222
4. After doing this, in a third terminal, we can run npm run publish and check if connection is OK (We should receive publisher connected to NATS log)

Publisher

Publisher script (npm run publish) will connect to nats server and create an example push of data to channel ticket:created.

Listener

Listener script (npm run listen) will connect to nats server and listen for data in channel ticket:created.

NATS Monitoring

To enable NATS monitoring, we need to forwar dpor 8222.

1. Check your pod name with command kubectl get pods
2. Write command kubectl port-forward nats-depl-7c95b5f667-zw5cc 8222:8222

After doing this, you will be able to go to http://localhost:8222, here are some importante sites

Useful URLs

• http://localhost:8222/streaming/channelsz: List of channels
• http://localhost:8222/streaming/channelsz?subs=1 Extended list of channels