How to Run Kubernetes with Calico

Kubernetes has become the de facto standard for container orchestration, allowing developers to manage and scale containerized applications effortlessly. When it comes to networking in Kubernetes, Calico stands out as a powerful and flexible solution. In this article, we'll explore how to run Kubernetes with Calico, step by step, guiding you through the process of setting up a robust networking layer for your containerized applications.

Prerequisites:

Before diving into the installation process, make sure you have the following prerequisites in place:

1. Kubernetes Cluster:
   Ensure you have a functional Kubernetes cluster up and running. If not, you can use tools like kubeadm, Minikube, or kind to set up a cluster.

2. kubectl:
   Make sure you have the Kubernetes command-line tool, kubectl, installed on your local machine to interact with your Kubernetes cluster.

Installation Steps:

Step 1: Install Calico CustomResourceDefinitions (CRDs):

kubectl apply -f https://docs.projectcalico.org/v3.19/manifests/custom-resources/custom-resources.yaml

Step 2: Deploy Calico Pods:

kubectl apply -f https://docs.projectcalico.org/v3.19/manifests/calico.yaml

This command deploys Calico components, including the Calico CNI plugin and necessary RBAC roles.

Step 3: Verify Calico Installation:

kubectl get pods -n kube-system | grep calico

Ensure that the Calico pods are in the "Running" state before proceeding.

Configuring Calico Network Policies:

Calico excels in implementing network policies to control the traffic between pods. Let's create a simple network policy example:

Step 4: Create a Network Policy:

# my-network-policy.yaml
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: allow-nginx
spec:
  podSelector:
    matchLabels:
      app: nginx
  ingress:
  - from:
    - podSelector:
        matchLabels:
          role: frontend

Apply the network policy:

kubectl apply -f my-network-policy.yaml

More Examples:

Example 1: Scaling Calico Nodes:

kubectl scale daemonset calico-node --to=5 -n kube-system

This scales the number of Calico nodes to 5. Adjust the value according to your cluster size.

Example 2: Troubleshooting Calico Issues:

kubectl logs -n kube-system -l k8s-app=calico-node

Check the logs to troubleshoot and diagnose any issues with the Calico nodes.

Congratulations! You've successfully set up Kubernetes with Calico, a robust networking solution that empowers you to manage and secure your containerized applications efficiently. Explore Calico's rich features, such as network policies, to enhance the security and performance of your Kubernetes cluster.