MSDN Documentation

Containerized Cloud Deployment

This tutorial guides you through the process of deploying your applications as containers in the cloud. Containerization offers a consistent and portable way to package and run applications, simplifying deployment across various environments.

What are Containers?

Containers are lightweight, standalone, executable packages of software that include everything needed to run an application: code, runtime, system tools, system libraries, and settings. They virtualize the operating system, allowing multiple containers to run on a single OS instance.

Why Use Containers for Cloud Deployment?

• Consistency: Eliminates "it works on my machine" problems by ensuring the environment is the same from development to production.
• Portability: Applications packaged in containers can run on any cloud provider or on-premises infrastructure that supports container runtimes.
• Isolation: Containers isolate applications from each other and from the host system, enhancing security and stability.
• Efficiency: Containers are much smaller and start faster than traditional virtual machines.
• Scalability: Containers are ideal for microservices architectures, allowing individual services to be scaled independently.

Key Container Technologies

The most prominent containerization technology is Docker. Docker provides the tools and platform to build, ship, and run containerized applications.

Docker Fundamentals

• Dockerfile: A text document that contains all the commands a user could call on the command line to assemble an image.
• Image: A lightweight, standalone, executable package that includes everything needed to run a piece of software, including the code, runtime, system tools, system libraries, and settings.
• Container: A runnable instance of a Docker image.

Creating Your First Container Image

Let's create a simple web application and containerize it using Docker. We'll use a basic Python Flask application as an example.

1. Create a Simple Flask Application (app.py)

from flask import Flask

app = Flask(__name__)

@app.route('/')
def hello():
    return "Hello from a containerized cloud application!"

if __name__ == "__main__":
    app.run(host='0.0.0.0', port=5000)
            

2. Create a Dockerfile

This file defines how to build the Docker image.

# Use an official Python runtime as a parent image
FROM python:3.9-slim

# Set the working directory in the container
WORKDIR /app

# Copy the current directory contents into the container at /app
COPY . /app

# Install any needed packages specified in requirements.txt
RUN pip install --no-cache-dir -r requirements.txt

# Make port 5000 available to the world outside this container
EXPOSE 5000

# Define environment variable
ENV NAME World

# Run app.py when the container launches
CMD ["python", "app.py"]
            

3. Create a Requirements File (requirements.txt)

Flask==2.0.2
            

4. Build the Docker Image

Navigate to the directory containing your app.py, Dockerfile, and requirements.txt and run the following command:

docker build -t my-flask-app .
            

This command tags your image as my-flask-app.

5. Run the Container

Now, run a container from your newly built image:

docker run -d -p 5000:5000 my-flask-app
            

• -d: Run the container in detached mode (in the background).
• -p 5000:5000: Map port 5000 on your host machine to port 5000 inside the container.

You can now access your application by navigating to http://localhost:5000 in your web browser.

Deploying to the Cloud

Once you have your container image, you can push it to a container registry (like Docker Hub, Azure Container Registry, or Google Container Registry) and then deploy it to your chosen cloud platform (e.g., Azure App Service, AWS Elastic Beanstalk, Google Kubernetes Engine).

Next Steps

Learn how to manage and scale your containerized applications using orchestration tools like Kubernetes in the next tutorial: Orchestration with Kubernetes.