A MongoDB Dockerfile which enables a single-node replicaset

MongoDockerfile

FROM mongo:4.0

# files used to initialize the database
COPY ./init-db.d/ /docker-entrypoint-initdb.d

# add this command to a js file in the init directory
# formatted on newlines for better readability
RUN echo "rs.initiate(
  {
    _id: 'rs0', 
    members: [
      {
        _id: 0, 
        host: 'localhost:27017'
      }
    ]
  }); 
  rs.slaveOk();" > /docker-entrypoint-initdb.d/replica-init.js

# the important bits are calling out the replicaset, 
# binding the IP to 0.0.0.0, 
# and setting the oplogSize to something manageable
# these settings are for local development only, 
# and would likely be significantly different in a production deployment
CMD ["--replSet", "rs0", "--bind_ip", "0.0.0.0", "--oplogSize", "100"]