qoire / mongo-replica-set

A replica set of MongoDB in Docker Container

MongoDB Replica Set

A Replica Set of MongoDB running in a Docker container

Not For Production

The key motivation for this image is to have a ready-made replica set of MongoDB running inside docker container for CI tests and local development.

To run the container, execute the following command:

docker run -d -p 30303:30303 -p 30304:30304 -p 30305:30305 qoire/local-mongo-replica-set:v4.4.20-version.1

Wait for 30 to 35 seconds in order to properly start all database instances and replica-set initialization.

Versioning

Versioning follows the scheme of v<mongoDB semver>.version.<image version>

Configuration

Additionally, you can pass an env variable called HOST when running the container to configure the replica's hostname in docker. By default, it uses localhost.

Once ready, the replica-set can be accessed using the following connection string:

mongodb://localhost:30303,localhost:30304,localhost:30305/?replicaSet=rs0&readPreference=primary&ssl=false

If you're connecting from your host machine, you might need to set a new alias within /etc/hosts:

# /etc/hosts
127.0.0.1 HOST # where HOST is the value passed as env variable to the container

Aside on Configurations

If your usecase is like mine, connecting from the host machine for something like dockertest, with default ports (27017) already occupied, the default config should work for you. But if you'd like to run tests in parallel, then you must setup the docker run such that each image is occupying a different port on the host machine.

The replica sets Hostname and Port must match that of the host machines. So we cannot for example do mappings such as -p 30303:27017. See task test_run_alt_port for details.

Example:

docker run -d \
    -e "DB1_PORT=40303" \
    -e "DB2_PORT=40304" \
    -e "DB3_PORT=40305" \
    -p 40303:40303 \
    -p 40304:40304 \
    -p 40305:40305 \
    qoire/local-mongo-replica-set

Associated mongodb uri would be:

mongodb://localhost:40303,localhost:40304,localhost:40305/?replicaSet=rs0&readPreference=primary&ssl=false