Multi-document transactions are available for replica sets only. Transactions for sharded clusters are scheduled for MongoDB 4.2.
To build a development environment that supports multi-document transactions with MongoDB 4.0 we are using docker.
First of all, create a docker network.
docker network create my-mongo-cluster
The next step is to create the MongoDB docker containers and start them.
docker run -d -p 27017:27017 --name mongo-node1 -d --net my-mongo-cluster mongo --replSet "rs0"
docker run -d -p 27018:27017 --name mongo-node2 -d --net my-mongo-cluster mongo --replSet "rs0"
docker run -d -p 27019:27017 --name mongo-node3 -d --net my-mongo-cluster mongo --replSet "rs0"
In order to form a replica set a configuration needs to be applied to one of the nodes.
docker exec -it mongo-node1 mongo
To initialize the replication a config object with connection details of all the member servers is required.
rs.initiate({
_id: "rs0",
version: 1,
members: [
{ "_id" : 0, "host" : "mongo-node1:27017", "priority" : 1 },
{ "_id" : 1, "host" : "mongo-node2:27017", "priority" : 0.5 },
{ "_id" : 2, "host" : "mongo-node3:27017", "priority" : 0.5 }
],
settings: {
}
})
The server you're connected to will be elected as a member of the replica set. By running rs.status(), you can view the status of other MongoDB members within the replica set.