Day 16 of my 90-Day Devops Project: Implementing Canary Deployment

Today, I focused on setting up the basics for canary deployment.

Project Overview

In my day 16 project, I established a canary deployment for a simple web app with Docker and kubernetes (minikube). This method basically enables a phased feature rollout minimizing the risks associated with new releases.

My Folder Structure

Day15-canarydeployment/

│

├── app/

│   ├── app.py

│   ├── requirements.txt

│   └── Dockerfile

│

├── canary/

│   ├── canary.py

│   ├── requirements.txt

│   └── Dockerfile

│

├── deployment/

│   └── k8s/

│       ├── deployment.yaml

│       └── service.yaml

│

└── scripts/

    ├── deploy.sh

    └── monitor.sh

Steps to Complete the Project

Step 1: Application Setup

1. 
   

   Create the Main Application

   
   
   
   
   
   • 
     File: app/app.py
     
   
   
   
   
   CODE Kopieren

    from flask import Flask
   
   
   
    app = Flask(__name__)
   
   
   
    @app.route('/')
   
    def home():
   
        return "Main Application is running!"
   
   
   
    if __name__ == '__main__':
   
        app.run(host='0.0.0.0', port=5000)
   
   

   
   
   

• 
  

  Dependencies: Create app/requirements.txt
  
  

  
  
  CODE Kopieren

   Flask==2.0.3
  
  

  
  
  


• 
  

  Dockerize the Application: Create app/Dockerfile
  
  

  
  
  CODE Kopieren

   FROM python:3.9
  
  
  
   WORKDIR /app
  
  
  
   COPY requirements.txt .
  
   RUN pip install --no-cache-dir -r requirements.txt
  
  
  
   COPY app.py .
  
  
  
   EXPOSE 5000
  
   CMD ["python", "app.py"]
  
  

  
  
  

Step 2: Canary Application Setup

1. 
   

   Create the Canary Application

   
   
   
   
   
   • 
     File: canary/canary.py
     
   
   
   
   
   CODE Kopieren

    from flask import Flask
   
   
   
    app = Flask(__name__)
   
   
   
    @app.route('/')
   
    def home():
   
        return "Canary Application is running!"
   
   
   
    if __name__ == '__main__':
   
        app.run(host='0.0.0.0', port=5001)
   
   

   
   
   

• 
  

  Dependencies: Create canary/requirements.txt
  
  

  
  
  CODE Kopieren

   Flask==2.0.3
  
  

  
  
  


• 
  

  Dockerize the Canary Application: Create canary/Dockerfile
  
  

  
  
  CODE Kopieren

   FROM python:3.9-slim
  
  
  
   WORKDIR /app
  
  
  
   COPY requirements.txt .
  
   RUN pip install --no-cache-dir -r requirements.txt
  
  
  
   COPY canary.py .
  
  
  
   EXPOSE 5001
  
   CMD ["python", "canary.py"]
  
  

  
  
  

Step 3: Kubernetes Deployment

1. 
   

   Define all Kubernetes Resources

   
   
   
   
   
   • 
     Deployments: Create deployment/k8s/deployment.yaml
     
   
   
   
   
   CODE Kopieren

    apiVersion: apps/v1
   
    kind: Deployment
   
    metadata:
   
      name: main-app
   
    spec:
   
      replicas: 3
   
      selector:
   
        matchLabels:
   
          app: main-app
   
      template:
   
        metadata:
   
          labels:
   
            app: main-app
   
        spec:
   
          containers:
   
          - name: main-app
   
            image: your-docker-repo/main-app:latest
   
            ports:
   
            - containerPort: 5000
   
   
   
    ---
   
    apiVersion: apps/v1
   
    kind: Deployment
   
    metadata:
   
      name: canary-app
   
    spec:
   
      replicas: 1
   
      selector:
   
        matchLabels:
   
          app: canary-app
   
      template:
   
        metadata:
   
          labels:
   
            app: canary-app
   
        spec:
   
          containers:
   
          - name: canary-app
   
            image: your-docker-repo/canary-app:latest
   
            ports:
   
            - containerPort: 5001
   
   

   
   
   

• 
  

  Services: Create deployment/k8s/service.yaml
  
  

  
  
  CODE Kopieren

   apiVersion: v1
  
   kind: Service
  
   metadata:
  
     name: main-app-service
  
   spec:
  
     type: ClusterIP
  
     selector:
  
       app: main-app
  
     ports:
  
       - port: 80
  
         targetPort: 5000
  
  
  
   ---
  
   apiVersion: v1
  
   kind: Service
  
   metadata:
  
     name: canary-app-service
  
   spec:
  
     type: ClusterIP
  
     selector:
  
       app: canary-app
  
     ports:
  
       - port: 81
  
         targetPort: 5001
  
  

  
  
  

Step 4: Deployment Scripts

1. 
   

   Create Deployment Script

   
   
   
   
   
   • 
     File: scripts/deploy.sh
     
   
   
   
   
   CODE Kopieren

    #!/bin/bash
   
   
   
    docker build -t your-docker-repo/main-app:latest ./app
   
    docker build -t your-docker-repo/canary-app:latest ./canary
   
   
   
    docker push your-docker-repo/main-app:latest
   
    docker push your-docker-repo/canary-app:latest
   
   
   
    kubectl apply -f deployment/k8s/
   
   

   
   
   


2. 
   

   Monitoring Script

   
   
   
   
   
   • 
     File: scripts/monitor.sh
     
   
   
   
   
   CODE Kopieren

    #!/bin/bash
   
   
   
    kubectl logs -l app=main-app
   
    kubectl logs -l app=canary-app
   
    kubectl get deployments
   
   

   
   
   

Note: kindly replace all placeholders with your actual details

Challenges and Solutions

Challenges Encountered

1. 
   

   Minikube Not Installed:

   
   
   
   
   
   • Initially, Minikube wasn't recognized due to a PATH issue. To resolve this, I needed to configure the system PATH properly
     to ensure Minikube was accessible.
   
   
   
   


2. 
   

   Existing Minikube Instance:

   
   
   
   
   
   • Minikube detected an existing instance, which prevented me from starting a new cluster.
     To resolve this, I used the command minikube delete to remove the existing instance, and then I was able to start
     a new Minikube cluster using minikube start.
   
   
   
   


3. 
   

   kubectl Configuration:

   
   
   
   
   
   • To ensure kubectl could communicate with the Minikube cluster, I needed to configure the
     kubectl context to use Minikube by running the command kubectl config use-context minikube.
   
   
   
   

Solutions

1. 
   

   Verify Minikube Installation:

   
   
   
   
   
   • I checked the Minikube version with the command minikube version to ensure it was properly installed.
   
   
   
   


2. 
   

   Delete Existing Minikube Cluster:

   
   
   
   
   
   • The command minikube deletehelped to remove the existing Minikube instance, which allowed me to start a new cluster.
   
   
   
   


3. 
   

   Check VirtualBox:

   
   
   
   
   
   • I also ensured that VirtualBox was properly installed and running, as Minikube relies on a virtual machine provided
     by VirtualBox.
   
   
   
   


4. 
   

   Start Minikube:

   
   
   
   
   
   • After resolving the previous issues, I was able to start the Minikube cluster using the command minikube start.
   
   
   
   


5. 
   

   Access Logs:

   
   
   
   
   
   • To troubleshoot any remaining issues, I checked the Minikube logs using the command minikube logs.
   
   
   
   

These steps helped me to resolve the challenges I faced during the setup of the Minikube environment for this project.

Expected Results

• 
  Main Application: When you visit http://localhost:80, you should see the message:
  

  Main Application is running!

• 
  Canary Application: When you visit http://localhost:81, you should see the message:
  

  Canary Application is running!

Conclusion

Canary deployment ensures a gradual rollout of new application features, allowing teams to collect feedback and

monitor performance before the full release. By addressing challenges with effective Solutions, you can reduce risks and maintain stability.

I think it's a great approach, as it helps identify areas for improvement and allows for changes to be made before a complete release.