test-mongo-db-cluster

README.md

start_cluster
docker exec -it rc1 mongo
# then run the following in container rc1's mongo shell
rs.initiate(config = { _id: 'test-set', members: [{ _id: 0, host: 'rc1:27017' }, { _id: 1, host: 'rc2:27017' }, { _id: 2, host: 'rc3:27017' }] })
# while in there, populate some test data
use test
db.list.insertOne({ somekey: 'some value' })
db.list.insertOne({ title: 'cool' })
# finally quit
quit()
# once back to the docker host shell
docker stop rc1 rc2 rc3
# now the whole script 
test-cluster

_config.js

config = {
  _id: 'test-set',
  members: [
    { _id: 0, host: 'rc1:27017' },
    { _id: 1, host: 'rc2:27017' },
    { _id: 2, host: 'rc3:27017' }
  ]
}

main.sh

start_cluster() {
	for i in 1 2 3; do docker run --rm -p 3000$i:27017 --name rc$i --net mongo-cluster  -v ~/docker-storage/rc$i:/data/db -d mongo mongod --replSet test-set; done
}

runnode() {
    [ $# -lt 1 ] && echo "Usage: $FUNCNAME script" && return
    scriptname=$1
    shift
    others=$*
     docker run -it --rm --name my-node-script -v "$PWD":/usr/src/app -w /usr/src/app $others node:8 node $scriptname
}

test-cluster() {
    start_cluster
    until curl -s http://127.0.0.1:30003/ > /dev/null; do
        sleep 1
    done
    echo "mongo replSet memebers are up"
    echo "now wait for primary"
    until docker exec -it rc3 mongo --eval "rs.status()" | grep -q PRIMARY; do
        sleep 1;
    done
    # sleep extra time to make sure the replicaSet is ready for use
    sleep 2
    echo "primary is elected"
    cd ~/projects/test-mongodb
    runnode tt.js "--net=mongo-cluster"
}

tt.js

const MongoClient = require('mongodb').MongoClient

const url = 'mongodb://rc1:27017,rc2:27017,rc3:27017/test?replicaSet=test-set'
const db = 'test'

const main = async () => {
  console.log('start')
  const client = await MongoClient.connect(url, { useNewUrlParser: true })
  const col = client.db(db).collection('list')
  const res = await col.find({}, { limit: 5 }).toArray()
  console.log(res)
  await client.close()
  console.log('end')
}
main()