Network Policies

Relationships Between Network Policies and Cluster Types

• If you upgrade a CCE standard cluster with a tunnel network to a version that supports egress rules in in-place mode, the rules will not work because the node OS is not upgraded. In this case, reset the node.
• When a network policy is enabled for a cluster with a tunnel network, a pod's source IP address is embedded in the optional field of packets it sends to any Service CIDR block. This enables the configuration of network policy rules on the destination pod, taking into account the source IP address of the pod.

Using Ingress Rules Through YAML

• Scenario 1: Configure a network policy to allow only pods with specified labels to access the target pod.
  Figure 1 podSelector
  

  The pod labeled with role=db only permits access to its port 6379 from pods labeled with role=frontend. To achieve this, take the following steps:

  1. Create the access-ingress1.yaml file.

     vim access-ingress1.yaml

     File content:

     apiVersion: networking.k8s.io/v1
     kind: NetworkPolicy
     metadata:
       name: access-ingress1
       namespace: default
     spec:
       podSelector:                  # The rule applies only to pods labeled with role=db.
         matchLabels:
           role: db
       ingress:                      # This is an ingress rule.
       - from:
         - podSelector:              # Allow access only from pods labeled with role=frontend.
             matchLabels:
               role: frontend
         ports:                      # Only TCP can be used to access port 6379.
         - protocol: TCP
           port: 6379

  2. Run the following command to create the network policy defined in the access-ingress1.yaml file:

     kubectl apply -f access-ingress1.yaml

     Expected output:

     networkpolicy.networking.k8s.io/access-ingress1 created

• Scenario 2: Configure a network policy to allow only pods in a specific namespace to access the target pod.
  Figure 2 namespaceSelector
  

  The pod labeled with role=db only permits access to its port 6379 from pods in the namespace labeled with project=myproject. To achieve this, take the following steps:

  1. Create the access-ingress2.yaml file.

     vim access-ingress2.yaml

     File content:

     apiVersion: networking.k8s.io/v1
     kind: NetworkPolicy
     metadata:
       name: access-ingress2
     spec:
       podSelector:                  # The rule applies only to pods labeled with role=db.
         matchLabels:
           role: db
       ingress:                      # This is an ingress rule.
       - from:
         - namespaceSelector:        # Allow access only from pods in namespaces labeled with project=myproject.
             matchLabels:
               project: myproject
         ports:                      # Only TCP can be used to access port 6379.
         - protocol: TCP
           port: 6379

  2. Run the following command to create the network policy defined in the access-ingress2.yaml file:

     kubectl apply -f access-ingress2.yaml

     Expected output:

     networkpolicy.networking.k8s.io/access-ingress2 created

• Scenario 3: Configure a network policy to allow only pods with specific labels in a specific namespace to access the target pod.
  Figure 3 Using both podSelector and namespaceSelector
  

  The pod labeled with role=db only allows access to its port 6379 from pods with label role=frontend in the namespace labeled with project=myproject. To achieve this, take the following steps:

  1. Create the access-ingress3.yaml file.

     vim access-ingress3.yaml

     File content:

     apiVersion: networking.k8s.io/v1
     kind: NetworkPolicy
     metadata:
       name: access-ingress3
     spec:
       podSelector:                  # The rule applies only to pods labeled with role=db.
         matchLabels:
           role: db
       ingress:                      # This is an ingress rule.
       - from:
         - namespaceSelector:        # Allow access only from pods in namespaces labeled with project=myproject.
             matchLabels:
               project: myproject
           podSelector:              # Allow access only from pods labeled with role=frontend.
             matchLabels:
               role: frontend
         ports:                      # Only TCP can be used to access port 6379.
         - protocol: TCP
           port: 6379

  2. Run the following command to create the network policy defined in the access-ingress3.yaml file:

     kubectl apply -f access-ingress3.yaml

     Expected output:

     networkpolicy.networking.k8s.io/access-ingress3 created

Using Egress Rules Through YAML

• Scenario 1: Controlled by a preset network policy, pods can only access specific addresses.
  Figure 4 ipBlock
  

  The pods labeled role=db only allow access to 172.16.0.0/16, excluding 172.16.0.40/32. To achieve this, take the following steps:

  1. Create the access-egress1.yaml file.

     vim access-egress1.yaml

     File content:

     apiVersion: networking.k8s.io/v1
     kind: NetworkPolicy
     metadata:
       name: access-egress1
       namespace: default
     spec:
       policyTypes:                  # This policy type must be specified for egress rules.
         - Egress
       podSelector:                  # The rule applies only to pods labeled with role=db.
         matchLabels:
           role: db
       egress:                       # This is an egress rule.
       - to:
         - ipBlock:
             cidr: 172.16.0.0/16    # Allows access to this CIDR block in the outbound direction.
             except:
             - 172.16.0.40/32        # Blocks access to this CIDR block, which is in the range specified by the cidr parameter.

  2. Run the following command to create the network policy defined in the access-egress1.yaml file:

     kubectl apply -f access-egress1.yaml

     Expected output:

     networkpolicy.networking.k8s.io/access-egress1 created

• Scenario 2: Controlled by a preset network policy, a pod can only be accessed by pods with specific labels, while this pod itself can only access specific pods.
  Figure 5 Using both ingress and egress
  

  The pod labeled with role=db only permits access to its port 6379 from pods labeled with role=frontend, and this pod can only access the pods labeled with role=web. You can use the same rule to configure both ingress and egress in a network policy. To achieve this, take the following steps:

  1. Create the access-egress2.yaml file.

     vim access-egress2.yaml

     File content:

     apiVersion: networking.k8s.io/v1
     kind: NetworkPolicy
     metadata:
       name: access-egress2
       namespace: default
     spec:
       policyTypes:
       - Ingress
       - Egress
       podSelector:                  # The rule applies only to pods labeled with role=db.
         matchLabels:
           role: db
       ingress:                      # This is an ingress rule.
       - from:
         - podSelector:              # Allow access only from pods labeled with role=frontend.
             matchLabels:
               role: frontend
         ports:                      # Only TCP can be used to access port 6379.
         - protocol: TCP
           port: 6379
       egress:                       # This is an egress rule.
       - to:
         - podSelector:              # The rule takes effect for pods with the role=web label.
             matchLabels:
               role: web

  2. Run the following command to create the network policy defined in the access-egress2.yaml file:

     kubectl apply -f access-egress2.yaml

     Expected output:

     networkpolicy.networking.k8s.io/access-egress2 created