mongodb-replicaset

Docker-compose tu deploy a mongodb cluster with 4 replicas

Configuration and Credentials

.env file

If you still don't have it, copy the .env.example and update it with your desired values.

Secrets

The secrets like the MONGO_ADMIN_PASSWORD should never be defined on the .env file for security reasons. Is better to configure it directly on the host and avoid have it published. To generate it you can use this command export MONGO_ADMIN_PASSWORD=$(pwgen -1s 20)

Key file

Is high recommended having a MongoDB cluster with ReplicaSet with enforced authentication between members. Because of that, on our (docker-compose.yml)[docker-compose.yml] we have a volume to map a keyfile. If you don't have any key file, generate one where you have set the ${DATA_PATH} on the .env file:

openssl rand -base64 756 > ${DATA_PATH}/mongo-key/rs.key
chmod 400 ${DATA_PATH}/mongo-key/rs.key

Probably, you should grant ownership to user with id 999 chown 999:999 ${DATA_PATH}/mongo-key/rs.key to the key file to avoid permissions issues.

Initiate the cluster

On the container named mongo-1 run the initiate.sh script to configure the replicaset:

docker exec -ti mongo-1 sh initiate.sh

Check status

docker run -ti --rm --network mongodb-replicaset_default mongo:4.4 mongo \
  --host mongo-1 \
  -u root_username \
  -p current_password \
  --authenticationDatabase admin \
  --eval "printjson(rs.status())"