Docker - Setting MongoDB

Docker - Setting up MongoDB

MongoDB is a popular NoSQL document-oriented database frequently used in modern web applications. Docker makes it easy to run MongoDB instances for development, testing, or even production.

This guide shows how to run a MongoDB server container and connect to it from another container using Docker’s networking features.

Running the MongoDB Server Container

Step 1: Pull the official MongoDB image from Docker Hub.

# Pull the latest official MongoDB image
docker pull mongo

Step 2: Create a user-defined network. This allows containers to easily communicate using their names.

docker network create mongo-net

Step 3: Run the MongoDB server container, connecting it to the network and setting necessary environment variables.

docker run -d \
  --name mongodb-server \
  --network mongo-net \
  -e MONGO_INITDB_ROOT_USERNAME=mongoadmin \
  -e MONGO_INITDB_ROOT_PASSWORD=secret \
  mongo

Explanation:

• -d: Run in detached mode (background).
• --name mongodb-server: Assign a name to the container.
• --network mongo-net: Connect the container to our user-defined network.
• -e MONGO_INITDB_ROOT_USERNAME=...: Sets the root username on first initialization.
• -e MONGO_INITDB_ROOT_PASSWORD=...: Sets the root password on first initialization. Use strong passwords in real scenarios!
• mongo: The image to use.

Optional: For data persistence (highly recommended), mount a volume:

# Create a named volume first (optional, Docker creates it if it doesn't exist)
# docker volume create mongo-data

docker run -d \
  --name mongodb-server \
  --network mongo-net \
  -v mongo-data:/data/db \
  -e MONGO_INITDB_ROOT_USERNAME=mongoadmin \
  -e MONGO_INITDB_ROOT_PASSWORD=secret \
  mongo

-v mongo-data:/data/db maps the named volume mongo-data to the default MongoDB data directory inside the container, ensuring your data survives container restarts or removal.

Connecting with a MongoDB Client Container

Step 4: Run another container using the same mongo image to act as a client. Connect it to the same network.

# Run a temporary interactive mongo container connected to the network
docker run -it --rm --network mongo-net mongo bash

• -it: Run interactively with a TTY.
• --rm: Automatically remove the container when it exits.
• --network mongo-net: Connect to the same network as the server.
• mongo: Use the mongo image.
• bash: Start a bash shell inside the client container.

Step 5: Inside the client container’s bash shell, connect to the server using the mongosh (or older mongo) client, referencing the server container by its name (mongodb-server).

# Inside the client container's shell:
mongosh --host mongodb-server --username mongoadmin --password secret

Explanation:

• mongosh: The MongoDB shell command.
• --host mongodb-server: Connect to the server using its container name (Docker resolves this via the user-defined network).
• --username mongoadmin: Use the root username defined earlier.
• --password secret: Use the root password defined earlier. (You might be prompted interactively if you omit --password secret).

If the connection is successful, you will see the MongoDB shell prompt (>).

Step 6: You can now run MongoDB commands.

# Example commands inside the MongoDB shell:
show dbs
use myNewDatabase
db.myCollection.insertOne({ name: "Docker Test" })
db.myCollection.find()

Type exit to leave the MongoDB shell, and exit again to leave the client container (which will be removed due to --rm). Your mongodb-server container continues running in the background.