Docker for efficient development
Lesson 2 - Docker compose and our first containers
Let’s get hands-on and create our very first container! Ready to roll? Here’s how it goes.
- Step 1: Find Your Container Images
- Where do you get the apps or images you want to run?
- Docker Hub is the place to start — with over 9.6 million images available, from Postgres to MSSQL and beyond.
- Step 2: Ways to Run Containers
- You can start containers from the terminal using Docker commands.
- Or use a handy UI like Docker Desktop (which we’ll check out soon).
- There’s also Portainer, a web-based UI, which we cover in our bonus lesson.
- Step 3: Docker Run Commands — Tedious but Powerful
- Running containers via the terminal means typing long commands with lots of arguments — not fun to memorize or reuse.
- Step 4: Enter Docker Compose Files — Your New Best Friend
- Docker Compose files bundle all those arguments into a neat, reusable format. You can:
- Redeploy them easily across machines
- Share them via email or version control
- To start containers from a Compose file, run:
- To stop containers, run:
- Pro tip: The -d (detached) flag makes sure containers keep running after you close the terminal.
- Step 5: What’s Inside a Docker Compose File?
- Here’s a quick rundown:
- version: Docker Compose spec version (usually no need to change)
- services: Your containers — here, an example with MS SQL Server
- container_name: Pick a name you like
- image: The exact Docker Hub image name (e.g., mcr.microsoft.com/mssql/server:2017-latest)
- ports: Map container ports to your host, so you can access the app (e.g., 4033:1433 means port 4033 on your PC maps to 1433 inside the container)
- volumes: Map container folders to your host to persist data (e.g., SQL Server stores data under /var/opt/mssql)
- environment: Set environment variables like passwords or license acceptance
- Step 6: Let’s See Docker Desktop in Action
- After installing Docker, open Docker Desktop.
- You’ll see tabs for containers, images, and volumes.
- Under “Images,” search for what you want (like nginx, gitlab, or mssql).
- Click an image and hit “Run” to download and start it — simple as that!
- Docker Desktop gives you a GUI alternative to the terminal commands.
- Step 7: Deploying Our First MS SQL Container with Docker Compose
- Download the sample Docker Compose file for MS SQL from our resources.
- Open a terminal like PowerShell or CMD and navigate to the folder with the Compose file.
- Run:
- Docker will download the SQL Server image once and then launch your container.
- Step 8: What Happens Behind the Scenes?
- Docker creates a private network for your containers — they’re isolated but connected.
- Volumes are created automatically for data storage.
- The MS SQL container runs in the background — check it in Docker Desktop under “Containers.”
- Step 9: Connect to Your MS SQL Server
- Use your favorite SQL client (like SQL Server Management Studio).
- Connect to localhost on port 4033 (mapped from the container).
- Login with the SA user and the password you set in the Compose file.
- Voilà — you have a full SQL Server instance running in a container!
- Step 10: Connect DataFlex to Your Containerized Database
- Open DataFlex, go to Databases > SQL Connection Manager.
- Add a new connection with:
- Server: localhost
- Username: SA
- Password: the one you specified
- Test connection — success!
- Now you can work with your containerized database just like any other.
- Step 11: Stop Your Container When Done
- To stop and remove the container, just run:
- Or stop it from Docker Desktop’s container list.
And that’s it! You just deployed your first containerized MS SQL Server — easy, fast, and clean.
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Docker for efficient development
