Mastering Canary Deployments on Kubernetes: A Comprehensive Guide

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Canary Deployments By: John Abhilash / November 29, 2023

In the dynamic realm of software development, the ability to seamlessly release new application versions without compromising stability or user experience is paramount. Canary deployments, a proven strategy for risk-mitigated rollouts, have emerged as a frontrunner in achieving this goal. By gradually introducing new versions to a small subset of users, canary deployments enable thorough testing and monitoring before widespread adoption.

Kubernetes, a popular container orchestration platform, has become the go-to choice for managing microservices-based applications. Integrating canary deployments into a Kubernetes environment with Nginx Ingress Controller, a versatile load balancer, empowers developers to streamline the release process and ensure a smooth transition for users.

Embarking on the Canary Deployments Journey

 

To implement canary deployments on Kubernetes using Nginx Ingress Controller, follow these meticulously crafted steps:

  1. Craft the Deployment: Begin by crafting a deployment manifest for the new application version. This manifest outlines the resources required to run the new version in a canary environment. For an Nginx application, the deployment manifest might resemble:

    YAML

    apiVersion: apps/v1
    kind: Deployment
    metadata:
    name: nginx-canary
    spec:
    replicas: 1
    selector:
    matchLabels:
    app: nginx
    version: canary
    template:
    metadata:
    labels:
    app: nginx
    version: canary
    spec:
    containers:
    - name: nginx
    image: nginx:latest
    ports:
    - containerPort: 80

    This deployment configuration will create a single pod running the latest Nginx image.

  2. Establish the Service: Next, establish a service manifest for the new application version. This manifest exposes the new version to the broader cluster, enabling communication and interaction. For an Nginx application, the service manifest might take the form of:

    YAML
    apiVersion: v1
    kind: Service
    metadata:
      name: nginx-canary
    spec:
      selector:
        app: nginx
        version: canary
      ports:
      - port: 80
        targetPort: 80
    

    This service configuration exposes the new application version on port 80, making it accessible within the cluster.

  3. Craft the Ingress Rule: Finally, craft an Ingress rule manifest to direct traffic to the new application version. This manifest leverages the Ingress controller to intelligently route incoming requests. For an Nginx application, the Ingress rule manifest might resemble:

    YAML
    apiVersion: networking.k8s.io/v1
    kind: Ingress
    metadata:
      name: nginx-ingress
    spec:
      rules:
      - host: nginx.example.com
        http:
          paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: nginx-canary
                port: 80
    

    This Ingress rule configuration directs all traffic to the nginx-canary service, ensuring that requests land on the new application version.

Deploying and Monitoring the Canary Deployment

With the deployment, service, and Ingress rule manifests in place, initiate the deployment of the new application version by adding a pod annotation:

Bash
kubectl annotate pod nginx-deployment version=canary

This annotation signals to the Ingress controller that the nginx-deployment pod should be treated as the canary version.

Once deployed, meticulously monitor the canary deployment’s performance. Utilize metrics such as CPU usage, memory consumption, error rates, and response times to assess the stability and efficiency of the new version.

If the canary deployment proves successful, roll it out to the entire user base by removing the version=canary annotation:

Bash
kubectl annotate pod nginx-deployment version=

Scaling the Canary Deployment

To evaluate the canary deployment’s performance under varying load conditions, consider scaling it up or down. Utilize the Kubernetes HorizontalPodAutoscaler (HPA) to automate scaling based on CPU or memory usage. For an Nginx application, an HPA manifest might look like:

 

YAML
apiVersion: autoscaling/v2beta1
kind: HorizontalPodAutoscaler
metadata:
  name: nginx-canary
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: nginx-canary
  minReplicas: 1
  maxReplicas: 10
targetCPUUtilizationPercentage: 80

 


This HPA configuration instructs the Ingress controller to scale the nginx-canary deployment up to 10 replicas if the CPU usage of the nginx-canary deployment reaches 80%.

Rolling Back the Canary Deployment

In case the canary deployment encounters issues, a rollback mechanism is crucial to restore stability. To roll back to the previous version, simply remove the version=canary annotation from the nginx-deployment pod.

External Resources

To further explore canary deployments on Kubernetes with Nginx Ingress Controller, consider the following external resources:

By carefully implementing canary deployments on Kubernetes with Nginx Ingress Controller, developers can confidently release new application versions without jeopardizing user experience or system stability. This approach fosters a continuous delivery pipeline that enables rapid innovation and adaptation in the ever-evolving software landscape.

 

Visit BootLabs’ website to learn more: https://www.bootlabstech.com/

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