Docker Compose

Thursday, Mar 20, 2025| Tags: Docker

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Docker Compose

1. Setup

2. docker-compose vs docker compose

3. Plan

    a) Create a Docker Network

    b) Create the MongoDB Container

    c) Create the Mongo Express Container

    d) Verify Containers

    e) Test Connection

4. Observations

5. Docker Compose

6. Cleanup

7. Conclusion


Setup

For this post, we will need docker.

Let’s quickly set up the environment and verify the installation.


$ sudo apt update
$ sudo apt install -y docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin
$ sudo usermod -aG docker $USER

Verify the installation:


$ docker --version
Docker version 28.0.1, build 068a01e

Edward J. Sabol, on Facebook reminded me that if I am using recent version of docker then I can use the compose sub-command of the docker also in my examples.

Honestly speaking this was news to me, I had no clue if it was existed.

All I knew was docker-compose, standalone tool for managing multi-container Docker applications.

Just for fun, I am using the docker compose command in this post.

Having said, this will also work with docker-compose without any change.


‘docker-compose’ vs ‘docker compose’

docker-compose


1. It is commonly referred as 'Compose V1'.
2. It is Python-based tool.
3. It needs separate installation e.g. sudo apt install docker-compose.
4. It is slower comparative to 'docker compose'.

docker compose


1. It is referred as 'Compose V2'.
2. It is Go-based tool.
3. It is integrated with Docker CLI since Docker v20.10.0.
4. It is much faster than 'docker-compose'.

There is a stackoverflow post that goes into the details, if you are interested.

This is what I have on my box:


$ docker compose version
Docker Compose version v2.33.1

$ docker-compose version
docker-compose version 1.29.2, build unknown
docker-py version: 5.0.3
CPython version: 3.12.3
OpenSSL version: OpenSSL 3.0.13 30 Jan 2024

I have created an alias dps for the command docker ps, as shown below:


alias dps='docker ps --format "Container ID: {{.ID}}\nImage: {{.Image}}\nCommand: {{.Command}}\nCreated: {{.CreatedAt}}\nStatus: {{.Status}}\nPorts: {{.Ports}}\nNames: {{.Names}}\n"'

For this demo, I am going to use the latest MongoDB and Mongo Express images.


Plan

The goal is to create a container running Mongo Express, linked to a MongoDB container.

We will start with a simple straight forward approach using just docker command.


Create a Docker Network

First, let’s create a docker network named: mongo-network


$ docker network create mongo-network
7ca8d14845c684336d8e494515670675a8685646455e3761a0e88b0ff4e3234e

$ docker network ls
NETWORK ID     NAME            DRIVER    SCOPE
1240c8ea9eb8   bridge          bridge    local
d0b60d358dfb   host            host      local
7ca8d14845c6   mongo-network   bridge    local

Create the MongoDB Container

Next, We will create a MongoDB container:


$ docker run -d \
  -p 27017:27017 \
  -e MONGO_INITDB_ROOT_USERNAME=admin \
  -e MONGO_INITDB_ROOT_PASSWORD=supersecret \
  --network mongo-network \
  --name mongodb \
  mongo
048833d02f2693bf7bae641611cc466698fb5857b6503ef5743054e9a5518a31

Create the Mongo Express Container

Now, we will create the Mongo Express container.


$ docker run -d \
  -p 8081:8081 \
  -e ME_CONFIG_MONGODB_ADMINUSERNAME=admin \
  -e ME_CONFIG_MONGODB_ADMINPASSWORD=supersecret \
  -e ME_CONFIG_MONGODB_SERVER=mongodb \
  --network mongo-network \
  --name mongo-express \
  mongo-express
a82c59ffbee01f0b1d466b747e8288846c1e11f187205e10fddc6637f864c878

Verify Containers

Check the status of both containers:


$ dps
Container ID: a82c59ffbee0
Image: mongo-express
Command: "/sbin/tini -- /dock…"
Created: 2025-03-20 19:14:21 +0000 GMT
Status: Up About a minute
Ports: 0.0.0.0:8081->8081/tcp, [::]:8081->8081/tcp
Names: mongo-express

Container ID: 048833d02f26
Image: mongo
Command: "docker-entrypoint.s…"
Created: 2025-03-20 19:11:09 +0000 GMT
Status: Up 4 minutes
Ports: 0.0.0.0:27017->27017/tcp, [::]:27017->27017/tcp
Names: mongodb

Test Connection

Mongo Express should be accessible at http://localhost:8081 using the credential admin/pass.


Observations

I found this process tedious and time consuming.

Imagine if you had to create multiple containers manually, it would quickly become a nightmare.


Docker Compose

To make your life easy and comfortable, docker compose, comes into the picture.


Advantages of Docker Compose


  • Define and manage multiple containers in a single file.

  • Handles dependenciesy efficiently e.g., MongoDB starts before Mongo Express.

  • Automatically creates a network for all containers.

  • No need to remember long commands for running containers.


Cleanup

Let’s stop and remove both containers including the network, so that we have a clean setup.


$ docker stop mongodb mongo-express
$ docker rm mongodb mongo-express
$ docker network rm mongo-network

Re-creating MongoDB and Mongo Express containers using docker compose.

First, we will create the configuration file: docker-compose.yml


version: '3.8'
services:
  mongodb:
    image: mongo
    ports:
      - 27017:27017
    environment:
      - MONGO_INITDB_ROOT_USERNAME=admin
      - MONGO_INITDB_ROOT_PASSWORD=supersecret

  mongo-express:
    image: mongo-express
    ports:
      - 8081:8081
    environment:
      - ME_CONFIG_MONGODB_ADMINUSERNAME=admin
      - ME_CONFIG_MONGODB_ADMINPASSWORD=supersecret
      - ME_CONFIG_MONGODB_SERVER=mongodb
    depends_on:
      - "mongodb"

That’s it all, we need.

To start the containers, simply run one command:


$ docker compose up -d
✔ Network docker-compose_default            Created             0.1s
✔ Container docker-compose-mongodb-1        Started             0.3s
✔ Container docker-compose-mongo-express-1  Started             0.3s

Did you notice, it automatically created the network for us!

Let’s verify the status of both containers:


$ dps
Container ID: 4bfd8ccc3715
Image: mongo
Command: "docker-entrypoint.s…"
Created: 2025-03-20 19:32:20 +0000 GMT
Status: Up About a minute
Ports: 0.0.0.0:27017->27017/tcp, [::]:27017->27017/tcp
Names: docker-compose_mongodb_1

Container ID: 2d34f54091b6
Image: mongo-express
Command: "/sbin/tini -- /dock…"
Created: 2025-03-20 19:32:20 +0000 GMT
Status: Up About a minute
Ports: 0.0.0.0:8081->8081/tcp, [::]:8081->8081/tcp
Names: docker-compose_mongo-express_1

Mongo Express is still accessible at: http://localhost:8081


To stop both the containers, simply run one command:


$ docker compose down
✔ Container docker-compose-mongodb-1        Removed             0.7s
✔ Container docker-compose-mongo-express-1  Removed             0.9s
✔ Network docker-compose_default            Removed             0.6s

Conclusion

Isn’t it much simpler and easier to manage?

This is just the tip of the iceberg when it comes to docker compose.


Keep Hacking !!

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