Tutorial: Configure Azure CNI networking in Azure Kubernetes Service (AKS) using Ansible

Important

Ansible 2.8 (or later) is required to run the sample playbooks in this article.

Azure Kubernetes Service (AKS) makes it simple to deploy a managed Kubernetes cluster in Azure. AKS reduces the complexity and operational overhead of managing Kubernetes by offloading much of that responsibility to Azure. As a hosted Kubernetes service, Azure handles critical tasks like health monitoring and maintenance for you. The Kubernetes masters are managed by Azure. You only manage and maintain the agent nodes. As a managed Kubernetes service, AKS is free - you pay only for the agent nodes within your clusters; not for the masters.

Using AKS, you can deploy a cluster using the following network models:

  • Kubenet networking - Network resources are typically created and configured as the AKS cluster is deployed.
  • Azure CNI networking - AKS cluster is connected to existing virtual network (VNET) resources and configurations.

For more information about networking to your applications in AKS, see Network concepts for applications in AKS.

In this tutorial, Ansible is used to:

  • Create an AKS cluster
  • Configure Azure CNI networking

Prerequisites

  • Azure subscription: If you don't have an Azure subscription, create a free account before you begin.
  • Azure service principal: Create a service principal, making note of the following values: appId, displayName, password, and tenant.

Create a virtual network and subnet

The sample playbook code in this section is used to:

  • Create a virtual network
  • Create a subnet within the virtual network

Save the following playbook as vnet.yml:

- name: Create vnet
  azure_rm_virtualnetwork:
      resource_group: "{{ resource_group }}"
      name: "{{ name }}"
      address_prefixes_cidr:
          - 10.0.0.0/8

- name: Create subnet
  azure_rm_subnet:
      resource_group: "{{ resource_group }}"
      name: "{{ name }}"
      address_prefix_cidr: 10.240.0.0/16
      virtual_network_name: "{{ name }}"
  register: subnet

Create an AKS cluster in the virtual network

The sample playbook code in this section is used to:

  • Create an AKS cluster within a virtual network.

Save the following playbook as aks.yml:

- name: List supported kubernetes version from Azure
  azure_rm_aks_version:
      location: "{{ location }}"
  register: versions

- name: Create AKS cluster within a VNet
  azure_rm_aks:
      resource_group: "{{ resource_group }}"
      name: "{{ name }}"
      dns_prefix: "{{ name }}"
      kubernetes_version: "{{ versions.azure_aks_versions[-1] }}"
      agent_pool_profiles:
        - count: 3
          name: nodepool1
          vm_size: Standard_D2_v2
          vnet_subnet_id: "{{ vnet_subnet_id }}"
      linux_profile:
          admin_username: azureuser
          ssh_key: "{{ lookup('file', '~/.ssh/id_rsa.pub') }}"
      service_principal:
          client_id: "{{ lookup('ini', 'client_id section=default file=~/.azure/credentials') }}"
          client_secret: "{{ lookup('ini', 'secret section=default file=~/.azure/credentials') }}"
      network_profile:
          network_plugin: azure
          docker_bridge_cidr: 172.17.0.1/16
          dns_service_ip: 10.2.0.10
          service_cidr: 10.2.0.0/24
  register: aks

Here are some key notes to consider when working with the sample playbook:

  • Use the azure_rm_aks_version module to find the supported version.

  • The vnet_subnet_id is the subnet created in the previous section.

  • The playbook loads ssh_key from ~/.ssh/id_rsa.pub. If you modify it, use the single-line format - starting with "ssh-rsa" (without the quotes).

  • The client_id and client_secret values are loaded from ~/.azure/credentials, which is the default credential file. You can set these values to your service principal or load these values from environment variables:

    client_id: "{{ lookup('env', 'AZURE_CLIENT_ID') }}"
    client_secret: "{{ lookup('env', 'AZURE_SECRET') }}"
    

Run the sample playbook

The sample playbook code in this section is used to test various features shown throughout this tutorial.

Save the following playbook as aks-azure-cni.yml:

---
- hosts: localhost
  vars:
      resource_group: aksansibletest
      name: aksansibletest
      location: eastus
  tasks:
     - name: Ensure resource group exists
       azure_rm_resourcegroup:
           name: "{{ resource_group }}"
           location: "{{ location }}"

     - name: Create vnet
       include_tasks: vnet.yml

     - name: Create AKS
       vars:
           vnet_subnet_id: "{{ subnet.state.id }}"
       include_tasks: aks.yml

     - name: Show AKS cluster detail
       debug:
           var: aks

Here are some key notes to consider when working with the sample playbook:

  • Change the aksansibletest value to your resource group name.
  • Change the aksansibletest value to your AKS name.
  • Change the eastus value to your resource group location.

Run the playbook using the ansible-playbook command:

ansible-playbook aks-azure-cni.yml

After running the playbook, you see output similar to the following results:

PLAY [localhost] 

TASK [Gathering Facts] 
ok: [localhost]

TASK [Ensure resource group exists] 
changed: [localhost]

TASK [Create vnet] 
included: /home/devops/aks-cni/vnet.yml for localhost

TASK [Create vnet] 
changed: [localhost]

TASK [Create subnet] 
changed: [localhost]

TASK [Create AKS] 
included: /home/devops/aks-cni/aks.yml for localhost

TASK [List supported kubernetes version from Azure] 
 [WARNING]: Azure API profile latest does not define an entry for
ContainerServiceClient

ok: [localhost]

TASK [Create AKS cluster with vnet] 
changed: [localhost]

TASK [Show AKS cluster detail] 
ok: [localhost] => {
    "aks": {
        "aad_profile": {},
        "addon": {},
        "agent_pool_profiles": [
            {
                "count": 3,
                "name": "nodepool1",
                "os_disk_size_gb": 100,
                "os_type": "Linux",
                "storage_profile": "ManagedDisks",
                "vm_size": "Standard_D2_v2",
                "vnet_subnet_id": "/subscriptions/BBBBBBBB-BBBB-BBBB-BBBB-BBBBBBBBBBBB/resourceGroups/aksansibletest/providers/Microsoft.Network/virtualNetworks/aksansibletest/subnets/aksansibletest"
            }
        ],
        "changed": true,
        "dns_prefix": "aksansibletest",
        "enable_rbac": false,
        "failed": false,
        "fqdn": "aksansibletest-0272707d.hcp.eastus.azmk8s.io",
        "id": "/subscriptions/BBBBBBBB-BBBB-BBBB-BBBB-BBBBBBBBBBBB/resourcegroups/aksansibletest/providers/Microsoft.ContainerService/managedClusters/aksansibletest",
        "kube_config": "..."
        },
        "location": "eastus",
        "name": "aksansibletest",
        "network_profile": {
            "dns_service_ip": "10.2.0.10",
            "docker_bridge_cidr": "172.17.0.1/16",
            "network_plugin": "azure",
            "network_policy": null,
            "pod_cidr": null,
            "service_cidr": "10.2.0.0/24"
        },
        "node_resource_group": "MC_aksansibletest_aksansibletest_eastus",
        "provisioning_state": "Succeeded",
        "service_principal_profile": {
            "client_id": "AAAAAAAA-AAAA-AAAA-AAAA-AAAAAAAAAAAA"
        },
        "tags": null,
        "type": "Microsoft.ContainerService/ManagedClusters",
        "warnings": [
            "Azure API profile latest does not define an entry for ContainerServiceClient",
            "Azure API profile latest does not define an entry for ContainerServiceClient"
        ]
    }
}

PLAY RECAP 
localhost                  : ok=9    changed=4    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Clean up resources

  1. Save the following code as delete_rg.yml.

    ---
    - hosts: localhost
      tasks:
        - name: Deleting resource group - "{{ name }}"
          azure_rm_resourcegroup:
            name: "{{ name }}"
            state: absent
          register: rg
        - debug:
            var: rg
    
  2. Run the playbook using the ansible-playbook command. Replace the placeholder with the name of the resource group to be deleted. All resources within the resource group will be deleted.

    ansible-playbook delete_rg.yml --extra-vars "name=<resource_group>"
    

    Notes:

    • Due to the register variable and debug section of the playbook, the results display when the command finishes.

Next steps