Create cross-project traffic network policies

This page provides instructions to configure cross-project traffic network policies in Google Distributed Cloud (GDC) air-gapped appliance.

Cross-project traffic refers to the communication between services and workloads from different project namespaces but within the same organization.

Services and workloads in a project are isolated from external services and workloads by default. However, services and workloads from different project namespaces and within the same organization can communicate with each other by applying cross-project traffic network policies.

Before you begin

To configure intra-project traffic network policies, you must have the following:

• The necessary identity and access roles. For more information, see Prepare predefined roles and access.
• An existing project. For more information, see Create a project.

Create a cross-project traffic policy

You can define ingress or egress cross-project traffic policies to manage the communication between projects.

Create an ingress firewall rule for cross-project traffic

For project workloads or services to allow connections from other workloads in another project, you must configure an ingress firewall rule to allow the inbound traffic of other project workloads.

Work through the following steps to create a new firewall rule and allow inbound traffic from workloads in another project:

Console

1. Within the GDC console of the project you are configuring, go to Networking > Firewall in the navigation menu to open the Firewall page.
2. Click Create in the action bar to begin creating a new firewall rule.

3. On the Firewall rule details page, fill out the following information:

   1. In the Name field, enter a valid name for your firewall rule.
   2. In the Direction of traffic section, select Ingress to allow inbound traffic from workloads in other projects.
   3. In the Target section, select one of the following options:
      • All user workloads: allow connections to the workloads of the project you are configuring.
      • Service: indicate that this firewall rule targets a specific service within the project you are configuring.
   4. If your target is a project service, select the name of the service from the list of available services on the Service drop-down menu.
   5. In the From section, select one of the following two options:
      • All projects: allow connections from workloads in all the projects.
      • Another project and All user workloads: allow connections from workloads in another project.
   6. If you want to transfer workloads only from another project, select a project that you can access from the list of projects on the Project ID drop-down menu.
   7. If your target is all user workloads, select one of the following options in the Protocols and ports section:
      • Allow all: allow connections using any protocol or port.
      • Specified protocols and ports: allow connections using only the protocols and ports that you specify in the corresponding fields for the ingress firewall rule.

4. On the Firewall rule details page, click Create.

You've now permitted connections from other project workloads. After creating the firewall rule, the rule is visible in a table on the Firewall page.

API

The following policy enables workloads in the PROJECT_1 project to permit connections from workloads in the PROJECT_2 project, as well as the return traffic for the same flows. Apply the policy:

kubectl --kubeconfig API_SERVER apply -f - <<EOF
apiVersion: networking.global.gdc.goog/v1
kind: ProjectNetworkPolicy
metadata:
  namespace: PROJECT_1
  name: allow-inbound-traffic-from-PROJECT_2
spec:
  policyType: Ingress
  subject:
    subjectType: UserWorkload
  ingress:
  - from:
    - projectSelector:
        projects:
          matchNames:
          - PROJECT_2
EOF

Replace API_SERVER with the API server's kubeconfig path. If you have not yet generated a kubeconfig file for the API server, see Sign in for details.

The preceding command allows PROJECT_2 to go to PROJECT_1, but doesn't allow connections initiated from PROJECT_1 to PROJECT_2. For the latter, you require a reciprocal policy in the PROJECT_2 project. Apply the reciprocal policy:

kubectl --kubeconfig API_SERVER apply -f - <<EOF
apiVersion: networking.global.gdc.goog/v1
kind: ProjectNetworkPolicy
metadata:
  namespace: PROJECT_2
  name: allow-inbound-traffic-from-PROJECT_1
spec:
  policyType: Ingress
  subject:
    subjectType: UserWorkload
  ingress:
  - from:
    - projectSelector:
        projects:
          matchNames:
          - PROJECT_1
EOF

Connections are now permitted to and from PROJECT_1 and PROJECT_2.