Tutorial: Update the custom image of Azure virtual machine scale sets using Ansible

บทความ
08/14/2024

Important

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

Azure virtual machine scale sets is an Azure feature that lets you configure a group of identical, load balanced VMs. There's no additional cost to scale sets and they're built from virtual machines. You pay only for the underlying compute resources such as the VM instances, load balancers, or Managed Disk storage. With scale sets, the management and automation layers are provided to run and scale your applications. You could instead manually create and manage individual VMs. However, there are two key benefits to using scale sets. They're built into Azure and they automatically scale your virtual machines to meet application needs.

After a VM is deployed, you configure the VM with the software your app needs. Instead of doing this configuration task for each VM, you can create a custom image. A custom image is a snapshot of an existing VM that includes any installed software. When you configure a scale set, you specify the image to use for that scale set's VMs. By using a custom image, each VM instance is identically configured for your app. Sometimes, you may need to update your scale set's custom image. That task is the focus of this tutorial.

In this article, you learn how to:

Configure two VMs with HTTPD
Create a custom image from an existing VM
Create a scale set from an image
Update the custom image

Prerequisites

Azure subscription: If you don't have an Azure subscription, create a free account before you begin.

Install Ansible: Do one of the following options:
- Install and configure Ansible on a Linux virtual machine
- Configure Azure Cloud Shell and - if you don't have access to a Linux virtual machine - create a virtual machine with Ansible.

Configure two VMs

The playbook code in this section creates two virtual machines with HTTPD installed on both.

The index.html page for each VM displays a test string:

First VM displays the value Image A
Second VM displays the value Image B

This string is meant to mimic configuring each VM with different software.

There are two ways to get the sample playbook:

Download the playbook and save it to create_vms.yml.
Create a new file named create_vms.yml. Insert the following code into the new file.

- name: Create two VMs (A and B) with HTTPS
  hosts: localhost
  connection: local
  vars:
    vm_name: vmforimage
    admin_username: testuser
    admin_password: Pass123$$$abx!
    location: eastus
  tasks:
  - name: Create a resource group
    azure_rm_resourcegroup:
      name: "{{ resource_group }}"
      location: "{{ location }}"

  - name: Create virtual network
    azure_rm_virtualnetwork:
      resource_group: "{{ resource_group }}"
      name: "{{ vm_name }}"
      address_prefixes: "10.0.0.0/16"

  - name: Create subnets for VM A and B
    azure_rm_subnet:
      resource_group: "{{ resource_group }}"
      virtual_network: "{{ vm_name }}"
      name: "{{ vm_name }}"
      address_prefix: "10.0.1.0/24"

  - name: Create Network Security Group that allows HTTP
    azure_rm_securitygroup:
      resource_group: "{{ resource_group }}"
      name: "{{ vm_name }}"
      rules:
        - name: HTTP
          protocol: Tcp
          destination_port_range: 80
          access: Allow
          priority: 1002
          direction: Inbound

  - name: Create public IP addresses for VM A and B
    azure_rm_publicipaddress:
      resource_group: "{{ resource_group }}"
      allocation_method: Static
      name: "{{ vm_name }}_{{ item }}"
    loop:
      - A
      - B
    register: pip_output

  - name: Create virtual network inteface cards for VM A and B
    azure_rm_networkinterface:
      resource_group: "{{ resource_group }}"
      name: "{{ vm_name }}_{{ item }}"
      virtual_network: "{{ vm_name }}"
      subnet: "{{ vm_name }}"
      public_ip_name: "{{ vm_name }}_{{ item }}"
      security_group: "{{ vm_name }}"
    loop:
      - A
      - B

  - name: Create VM A and B
    azure_rm_virtualmachine:
      resource_group: "{{ resource_group }}"
      name: "{{ vm_name }}{{ item }}"
      admin_username: "{{ admin_username }}"
      admin_password: "{{ admin_password }}"
      vm_size: Standard_B1ms
      network_interfaces: "{{ vm_name }}_{{ item }}"
      image:
        offer: UbuntuServer
        publisher: Canonical
        sku: 16.04-LTS
        version: latest
    loop:
      - A
      - B

  - name: Create VM Extension
    azure_rm_virtualmachineextension:
      resource_group: "{{ resource_group }}"
      name: testVMExtension
      virtual_machine_name: "{{ vm_name }}{{ item }}"
      publisher: Microsoft.Azure.Extensions
      virtual_machine_extension_type: CustomScript
      type_handler_version: 2.0
      auto_upgrade_minor_version: true
      settings: {"commandToExecute": "sudo apt-get -y install apache2"}
    loop:
      - A
      - B

  - name: Create VM Extension
    azure_rm_virtualmachineextension:
      resource_group: "{{ resource_group }}"
      name: testVMExtension
      virtual_machine_name: "{{ vm_name }}{{ item }}"
      publisher: Microsoft.Azure.Extensions
      virtual_machine_extension_type: CustomScript
      type_handler_version: 2.0
      auto_upgrade_minor_version: true
      settings: {"commandToExecute": "printf '<html><body><h1>Image {{ item }}</h1></body></html>' >> index.html; sudo cp index.html /var/www/html/"}
    loop:
      - A
      - B

  - debug:
      msg: "Public IP Address A: {{ pip_output.results[0].state.ip_address }}"

  - debug:
      msg: "Public IP Address B: {{ pip_output.results[1].state.ip_address }}"

Run the playbook using the ansible-playbook command, replacing myrg with your resource group name:

ansible-playbook create-vms.yml --extra-vars "resource_group=myrg"

Because of the debug sections of the playbook, the ansible-playbook command will print the IP address of each VM. Copy these IP addresses for later use.

Connect to the two VMs

In this section, you connect to each VM. As mentioned in the previous section, the strings Image A and Image B mimic having two distinct VMs with different configurations.

Using the IP addresses from the previous section, open a browser and connect to each VM.

Create images from each VM

At this point, you have two VMs with slightly different configurations (their index.html files).

The playbook code in this section creates a custom image for each VM:

image_vmforimageA - Custom image created for the VM that displays Image A on its home page.
image_vmforimageB - Custom image created for the VM that displays Image B on its home page.

There are two ways to get the sample playbook:

Download the playbook and save it to capture-images.yml.
Create a new file named capture-images.yml. Insert the following code into the new file:

- name: Capture VM Images
  hosts: localhost
  connection: local
  vars:
    vm_name: vmforimage
  tasks:

  - name: Stop and generalize VMs
    azure_rm_virtualmachine:
      resource_group: "{{ resource_group }}"
      name: "{{ vm_name }}{{ item }}"
      generalized: yes
    loop:
      - A
      - B

  - name: Create an images from a VMs
    azure_rm_image:
      resource_group: "{{ resource_group }}"
      name: "image_{{ vm_name }}{{ item }}"
      source: "{{ vm_name }}{{ item }}"
    loop:
      - A
      - B

Run the playbook using the ansible-playbook command, replacing myrg with your resource group name:

ansible-playbook capture-images.yml --extra-vars "resource_group=myrg"

Create scale set using Image A

In this section, a playbook is used to configure the following Azure resources:

Public IP address
Load balancer
Scale set that references image_vmforimageA

There are two ways to get the sample playbook:

Download the playbook and save it to create-vmss.yml.
Create a new file named create-vmss.yml. Insert the following code into the new file:

---
- hosts: localhost
  vars:
    vmss_name: vmsstest
    location: eastus
    admin_username: vmssadmin
    admin_password: User123!!!abc
    vm_name: vmforimage
    image_name: "image_vmforimageA"

  tasks:

    - name: Create public IP address
      azure_rm_publicipaddress:
        resource_group: "{{ resource_group }}"
        allocation_method: Static
        name: "{{ vmss_name }}"
      register: pip_output

    - name: Create a load balancer
      azure_rm_loadbalancer:
        name: "{{ vmss_name }}lb"
        location: "{{ location }}"
        resource_group: "{{ resource_group }}"
        public_ip: "{{ vmss_name }}"
        probe_protocol: Tcp
        probe_port: 80
        probe_interval: 10
        probe_fail_count: 3
        protocol: Tcp
        load_distribution: Default
        frontend_port: 80
        backend_port: 80
        idle_timeout: 4
        natpool_frontend_port_start: 50000
        natpool_frontend_port_end: 50040
        natpool_backend_port: 22
        natpool_protocol: Tcp

    - name: Create a scale set
      azure_rm_virtualmachinescaleset:
        resource_group: "{{ resource_group }}"
        name: "{{ vmss_name }}"
        vm_size: Standard_DS1_v2
        admin_username: "{{ admin_username }}"
        admin_password: "{{ admin_password }}"
        ssh_password_enabled: true
        capacity: 2
        virtual_network_name: "{{ vm_name }}"
        subnet_name: "{{ vm_name }}"
        upgrade_policy: Manual
        tier: Standard
        managed_disk_type: Standard_LRS
        os_disk_caching: ReadWrite
        image:
          name: "{{ image_name }}"
          resource_group: "{{ resource_group }}"
        load_balancer: "{{ vmss_name }}lb"

    - debug:
        msg: "Scale set public IP address: {{ pip_output.state.ip_address }}"

Run the playbook using the ansible-playbook command, replacing myrg with your resource group name:

ansible-playbook create-vmss.yml --extra-vars "resource_group=myrg"

Due to the debug section of the playbook, the ansible-playbook command will print the IP address of the scale set. Copy this IP address for later use.

Connect to the scale set

Using the IP address from the previous section, connect to the scale set.

As mentioned in the previous section, the strings Image A and Image B mimic having two distinct VMs with different configurations.

The scale set references the custom image named image_vmforimageA. Custom image image_vmforimageA was created from the VM whose home page displays Image A.

As a result, you see a home page that displays Image A.

Leave your browser window open as you continue to the next section.

Change custom image in scale set and upgrade instances

The playbook code in this section changes the scale set's image - from image_vmforimageA to image_vmforimageB. Also, all current virtual machines deployed by the scale set are updated.

There are two ways to get the sample playbook:

Download the playbook and save it to update-vmss-image.yml.
Create a new file named update-vmss-image.yml. Insert the following code into the new file:

- name: Update scale set image reference
  hosts: localhost
  connection: local
  vars:
    vmss_name: vmsstest
    image_name: image_vmforimageB
    admin_username: vmssadmin
    admin_password: User123!!!abc
  tasks:

  - name: Update scale set - second image
    azure_rm_virtualmachinescaleset:
      resource_group: "{{ resource_group }}"
      name: "{{ vmss_name }}"
      vm_size: Standard_DS1_v2
      admin_username: "{{ admin_username }}"
      admin_password: "{{ admin_password }}"
      ssh_password_enabled: true
      capacity: 3
      virtual_network_name: "{{ vmss_name }}"
      subnet_name: "{{ vmss_name }}"
      upgrade_policy: Manual
      tier: Standard
      managed_disk_type: Standard_LRS
      os_disk_caching: ReadWrite
      image:
        name: "{{ image_name }}"
        resource_group: "{{ resource_group }}"
      load_balancer: "{{ vmss_name }}lb"

  - name: List all of the instances
    azure_rm_virtualmachinescalesetinstance_facts:
      resource_group: "{{ resource_group }}"
      vmss_name: "{{ vmss_name }}"
    register: instances

  - debug:
      var: instances

  - name: manually upgrade all the instances 
    azure_rm_virtualmachinescalesetinstance:
      resource_group: "{{ resource_group }}"
      vmss_name: "{{ vmss_name }}"
      instance_id: "{{ item.instance_id }}"
      latest_model: yes
    with_items: "{{ instances.instances }}"

Run the playbook using the ansible-playbook command, replacing myrg with your resource group name:

ansible-playbook update-vmss-image.yml --extra-vars "resource_group=myrg"

Return to the browser and refresh the page to see that the virtual machine's underlying custom image is updated.

Clean up resources

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

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>"
```
Key points:
- Because of the register variable and debug section of the playbook, the results display when the command finishes.

Run az group delete to delete the resource group. All resources within the resource group will be deleted.
```
az group delete --name <resource_group>
```
Verify that the resource group was deleted by using az group show.
```
az group show --name <resource_group>
```

Run Remove-AzResourceGroup to delete the resource group. All resources within the resource group will be deleted.
```
Remove-AzResourceGroup -Name <resource_group>
```
Verify that the resource group was deleted by using Get-AzResourceGroup.
```
Get-AzResourceGroup -Name <resource_group>
```

Next steps

Ansible on Azure

แชร์ผ่าน

Tutorial: Update the custom image of Azure virtual machine scale sets using Ansible

Prerequisites

Configure two VMs

Connect to the two VMs

Create images from each VM

Create scale set using Image A

Connect to the scale set

Change custom image in scale set and upgrade instances

Clean up resources

Next steps

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