MongoDB Replica Set

This setup is for local development purposes.

Quickstart

1. Add this in your /etc/hosts

127.0.0.1 mongo1
127.0.0.1 mongo2
127.0.0.1 mongo3

2. Run docker compose

docker-compose up -d

Connect to MongoDB Database

use connection string

mongodb://localhost:27001/?replicaSet=rs0

Open MongoDB Shell in Docker

docker exec -it mongo1 sh -c "mongo --port 27001"

How it works

• Start 3 instances of mongodb
• On the first instance it runs the following Mongo Shell command using docker healthcheck config

rs.initiate(
  {
    _id : 'replica-set',
    members: [
      { _id : 0, host : "mongo1:27001" },
      { _id : 1, host : "mongo2:27002" },
      { _id : 2, host : "mongo3:27003" }
    ]
  }
)

• This causes all 3 instances to join the replica set named replica-set and start talking to each other
• One is elected to become the PRIMARY and the other two become SECONDARY instances