MongoDB Replica Set

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This service sets up a MongoDB replica set with three members.

Prerequisites

Generate a key file for the replica set:

openssl rand -base64 756 > ./secrets/rs0.key

Initialization

Start the services:
```
docker compose up -d
```
The services will automatically initialize the replica set through the mongo-init init container. This container:
- Waits for all MongoDB nodes to be healthy
- Connects to the primary node
- Initializes the replica set with internal container names
- Uses container-based networking for communication

Verify the replica set status:

docker exec -it mongodb-replicaset-mongo1-1 mongosh -u root -p password --authenticationDatabase admin --eval "rs.status()"

Services

mongo1: The first member of the replica set.
mongo2: The second member of the replica set.
mongo3: The third member of the replica set.

Configuration

TZ: The timezone for the container, default is UTC.
MONGO_VERSION: The version of the MongoDB image, default is 8.0.13.
MONGO_INITDB_ROOT_USERNAME: The root username for the database, default is root.
MONGO_INITDB_ROOT_PASSWORD: The root password for the database, default is password.
MONGO_INITDB_DATABASE: The initial database to create, default is admin.
MONGO_REPLICA_SET_NAME: The name of the replica set, default is rs0.
MONGO_PORT_OVERRIDE_1: The host port for the first member, default is 27017.
MONGO_PORT_OVERRIDE_2: The host port for the second member, default is 27018.
MONGO_PORT_OVERRIDE_3: The host port for the third member, default is 27019.

Volumes

secrets/rs0.key: The key file for authenticating members of the replica set.

Security

The replica set key file is mounted read-only and copied to /tmp inside the container with proper permissions (400). This approach ensures cross-platform compatibility (Windows/Linux/macOS) while maintaining security requirements. The key file is never modified on the host system.