Configuring the Calico network policy controller

Calico is an open-source plugin for Kubernetes that can be used to manage Kubernetes network policies. Calico extends the standard features of Kubernetes network policies, which enables you to:

• Apply policies to any object: pod, container, virtual machine, or interface.
• Specify a particular action in the policy rules: prohibit, allow, or log.
• Specify as a target or a source: port, port range, protocols, HTTP and ICMP attributes, IP address or subnet, and other objects.
• Regulate traffic using DNAT settings and traffic forwarding policies.

To configure the Calico network policy controller:

1. Create an nginx service
2. Isolate pods using network policies
3. Create network policies enabling service access

If you no longer need the resources you created, delete them.

Getting startedGetting started

1. Create an infrastructure:

   Manually

   Terraform

   1. Create a cloud network and subnet.

   2. Create security groups for the Managed Service for Kubernetes cluster and its node groups.

      Warning

      The configuration of security groups determines the performance and availability of the cluster and the services and applications running in it.

   3. Create a Managed Service for Kubernetes cluster and a node group in any suitable configuration. When creating them, specify the network, subnet, and the security groups prepared in advance. Also, enable the Calico network policy controller in the cluster:

      • In the management console, by selecting Enable network policy.
      • Using the CLI, by setting the --enable-network-policy flag.
      • Using the create method for the Cluster resource.

   1. If you do not have Terraform yet, install it.

   2. Get the authentication credentials. You can add them to environment variables or specify them later in the provider configuration file.

   3. Configure and initialize a provider. There is no need to create a provider configuration file manually, you can download it.

   4. Place the configuration file in a separate working directory and specify the parameter values. If you did not add the authentication credentials to environment variables, specify them in the configuration file.

   5. Download the k8s-calico.tf configuration file of the Managed Service for Kubernetes cluster to the same working directory. The file describes:

      • Network.

      • Subnet.

      • Managed Service for Kubernetes cluster.

      • Service account required for the Managed Service for Kubernetes cluster and node group.

      • Security groups which contain rules required for the Managed Service for Kubernetes cluster and its node groups.

        Warning

        The configuration of security groups determines the performance and availability of the cluster and the services and applications running in it.

   6. Specify the following in the configuration file:

      • Folder ID.
      • Kubernetes version for a Managed Service for Kubernetes cluster and node groups.
      • Managed Service for Kubernetes cluster CIDR.
      • Name of the Managed Service for Kubernetes cluster service account.

   7. Run the terraform init command in the directory with the configuration files. This command initializes the provider specified in the configuration files and enables you to use the provider resources and data sources.

   8. Make sure the Terraform configuration files are correct using this command:

      terraform validate
      

      If there are any errors in the configuration files, Terraform will point them out.

   9. Create the required infrastructure:

      1. Run the command to view planned changes:

         terraform plan
         

         If the resource configuration descriptions are correct, the terminal will display a list of the resources to modify and their parameters. This is a test step. No resources are updated.

      2. If you are happy with the planned changes, apply them:

         1. Run the command:

            terraform apply
            

         2. Confirm the update of resources.

         3. Wait for the operation to complete.

      All the required resources will be created in the specified folder. You can check resource availability and their settings in the management console.

2. Install kubectl and configure it to work with the created cluster.

3. Create a policy-test namespace in the Managed Service for Kubernetes cluster.

Create an nginx serviceCreate an nginx service

1. Create a pod with the nginx web server in the policy-test namespace. Use the Kubernetes Deployment API object:

   kubectl create deployment --namespace=policy-test nginx --image=nginx
   

   Result:

   deployment.apps/nginx created
   

2. Run the pod with nginx as a Kubernetes service:

   kubectl expose --namespace=policy-test deployment nginx --port=80
   

   Result:

   service/nginx exposed
   

3. Make sure the nginx web server is available. To do this, create a pod named access:

   kubectl run --namespace=policy-test access --rm -ti --image busybox /bin/sh
   

   A shell session opens on the access pod:

   If you don't see a command prompt, try pressing enter.
   / #
   

4. Connect to the nginx web server via the session on the access pod:

   wget -q nginx -O -
   

   The nginx web server is available:

   <!DOCTYPE html>
   <html>
   <head>
   ...
   <p><em>Thank you for using nginx.</em></p>
   </body>
   </html>
   

5. Exit the pod:

   / # exit
   

   The pod is deleted:

   Session ended, resume using 'kubectl attach access -c access -i -t' command when the pod is running
   pod "access" deleted
   

Isolate pods using network policiesIsolate pods using network policies

Isolate the policy-test namespace. As a result, the Calico network policy controller prevents connections to pods in this namespace:

kubectl create -f - <<EOF
kind: NetworkPolicy
apiVersion: networking.k8s.io/v1
metadata:
  name: deny
  namespace: policy-test
spec:
  podSelector:
    matchLabels: {}
EOF

Network policies are created:

networkpolicy.networking.k8s.io/deny created

Test whether isolation worksTest whether isolation works

1. Network policies isolated the nginx web server. To check this, create a pod named access:

   kubectl run --namespace=policy-test access --rm -ti --image busybox /bin/sh
   

   A shell session opens on the access pod:

   If you don't see a command prompt, try pressing enter.
   / #
   

2. Check if the access pod can access the nginx web server:

   wget -q --timeout=5 nginx -O -
   

   No connection is established:

   wget: download timed out
   / #
   

3. Exit the pod:

   / # exit
   

   The pod is deleted:

   Session ended, resume using 'kubectl attach access -c access -i -t' command when the pod is running
   pod "access" deleted
   

Create network policies enabling service accessCreate network policies enabling service access

Allow access to the nginx web server using network policies. Network policies will only allow the access pod to connect to it.

1. Create access-nginx network policies:

   kubectl create -f - <<EOF
   kind: NetworkPolicy
   apiVersion: networking.k8s.io/v1
   metadata:
     name: access-nginx
     namespace: policy-test
   spec:
     podSelector:
       matchLabels:
         app: nginx
     policyTypes:
     - Ingress
     - Egress
     ingress:
       - from:
         - podSelector:
             matchLabels:
               run: access
     egress:
       - to:
         - podSelector:
             matchLabels:
               app: nginx
   EOF
   

   Note

   Network policies will allow traffic from pods with the run: access Kubernetes label to pods with the app: nginx Kubernetes label. Labels are automatically added by kubectl based on the resource name.

   Network policies are created:

   networkpolicy.networking.k8s.io/access-nginx created
   

2. Create a pod named access:

   kubectl run --namespace=policy-test access --rm -ti --image busybox /bin/sh
   

   A shell session opens on the access pod:

   If you don't see a command prompt, try pressing enter.
   / #
   

3. Check if the access pod can access the nginx web server:

   wget -q --timeout=5 nginx -O -
   

   The connection is established:

   <!DOCTYPE html>
   <html>
   <head>
   <title>Welcome to nginx!</title>
   ...
   

4. Exit the pod:

   / # exit
   

   The pod is deleted:

   Session ended, resume using 'kubectl attach access -c access -i -t' command when the pod is running
   pod "access" deleted
   

Check the network isolation functionality for other podsCheck the network isolation functionality for other pods

The created access-nginx network policies allow connections for pods with the run: access Kubernetes label.

1. Create a pod with no run: access label:

   kubectl run --namespace=policy-test cant-access --rm -ti --image busybox /bin/sh
   

   A shell session opens on the cant-access pod:

   If you don't see a command prompt, try pressing enter.
   / #
   

2. Check if the cant-access pod can access the nginx web server:

   wget -q --timeout=5 nginx -O -
   

   No connection is established:

   wget: download timed out
   / #
   

3. Exit the pod:

   / # exit
   

   The pod is deleted:

   Session ended, resume using 'kubectl attach access -c access -i -t' command when the pod is running
   pod "cant-access" deleted
   

4. To delete the sample data, delete the namespace:

   kubectl delete ns policy-test
   

   Command result:

   namespace "policy-test" deleted
   

Delete the resources you createdDelete the resources you created

Delete the resources you no longer need to avoid paying for them: