Tutorial: Configure virtual machine scale sets in Azure using Ansible
Important
Ansible 2.9 (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.
In this article, you learn how to:
- Configure the resources for a VM
- Configure a scale set
- Scale the scale set by increasing it's VM instances
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 a scale set
The playbook code in this section defines the following resources:
- Resource group into which all of your resources will be deployed.
- Virtual network in the 10.0.0.0/16 address space
- Subnet within the virtual network
- Public IP address that allows you to access resources across the Internet
- Network security group that controls the flow of network traffic in and out of your scale set
- Load balancer that distributes traffic across a set of defined VMs using load balancer rules
- Virtual machine scale set that uses all the created resources
There are two ways to get the sample playbook:
Download the playbook and save the file as
vmss-create.yml.Create a new file named
vmss-create.yml. Insert the following code into the new file:
- hosts: localhost
vars:
resource_group: myResourceGroup
vmss_name: myvmscalesetname
vmss_lb_name: myScaleSetLb
location: eastus
admin_username: azureuser
admin_password: "{{ admin_password }}"
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: "{{ vmss_name }}"
address_prefixes: "10.0.0.0/16"
- name: Add subnet
azure_rm_subnet:
resource_group: "{{ resource_group }}"
name: "{{ vmss_name }}"
address_prefix: "10.0.1.0/24"
virtual_network: "{{ vmss_name }}"
- name: Create public IP address
azure_rm_publicipaddress:
resource_group: "{{ resource_group }}"
allocation_method: Static
name: "{{ vmss_name }}"
- name: Create Network Security Group that allows SSH
azure_rm_securitygroup:
resource_group: "{{ resource_group }}"
name: "{{ vmss_name }}"
rules:
- name: SSH
protocol: Tcp
destination_port_range: 22
access: Allow
priority: 1001
direction: Inbound
- name: Create a load balancer
azure_rm_loadbalancer:
resource_group: "{{ resource_group }}"
name: "{{ vmss_name }}lb"
location: "{{ location }}"
frontend_ip_configurations:
- name: "{{ vmss_name }}front-config"
public_ip_address: "{{ vmss_name }}"
backend_address_pools:
- name: "{{ vmss_name }}backend-pool"
probes:
- name: "{{ vmss_name }}prob0"
port: 8080
interval: 10
fail_count: 3
inbound_nat_pools:
- name: "{{ vmss_name }}nat-pool"
frontend_ip_configuration_name: "{{ vmss_name }}front-config"
protocol: Tcp
frontend_port_range_start: 50000
frontend_port_range_end: 50040
backend_port: 22
load_balancing_rules:
- name: "{{ vmss_name }}lb-rules"
frontend_ip_configuration: "{{ vmss_name }}front-config"
backend_address_pool: "{{ vmss_name }}backend-pool"
frontend_port: 80
backend_port: 8080
load_distribution: Default
probe: "{{ vmss_name }}prob0"
- name: Create VMSS
no_log: true
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: "{{ vmss_name }}"
subnet_name: "{{ vmss_name }}"
upgrade_policy: Manual
tier: Standard
managed_disk_type: Standard_LRS
os_disk_caching: ReadWrite
image:
offer: UbuntuServer
publisher: Canonical
sku: 16.04-LTS
version: latest
load_balancer: "{{ vmss_name }}lb"
data_disks:
- lun: 0
disk_size_gb: 20
managed_disk_type: Standard_LRS
caching: ReadOnly
- lun: 1
disk_size_gb: 30
managed_disk_type: Standard_LRS
caching: ReadOnly
Before running the playbook, see the following notes:
- In the
varssection, replace the{{ admin_password }}placeholder with your own password.
Run the playbook using ansible-playbook
ansible-playbook vmss-create.yml
After running the playbook, you see output similar to the following results:
PLAY [localhost]
TASK [Gathering Facts]
ok: [localhost]
TASK [Create a resource group]
changed: [localhost]
TASK [Create virtual network]
changed: [localhost]
TASK [Add subnet]
changed: [localhost]
TASK [Create public IP address]
changed: [localhost]
TASK [Create Network Security Group that allows SSH]
changed: [localhost]
TASK [Create a load balancer]
changed: [localhost]
TASK [Create Scale Set]
changed: [localhost]
PLAY RECAP
localhost : ok=8 changed=7 unreachable=0 failed=0
View the number of VM instances
The configured scale set currently has two instances. The following steps are used to confirm that value:
Sign in to the Azure portal.
Navigate to the scale set you configured.
You see the scale set name with the number of instances in parenthesis:
Standard_DS1_v2 (2 instances)You can also verify the number of instances with the Azure Cloud Shell by running the following command:
az vmss show -n myScaleSet -g myResourceGroup --query '{"capacity":sku.capacity}'The results of running the Azure CLI command in Cloud Shell show that two instances exist:
{ "capacity": 2, }
Scale out a scale set
The playbook code in this section retrieves information about the scale set and changes its capacity from two to three.
There are two ways to get the sample playbook:
Download the playbook and save it to
vmss-scale-out.yml.Create a new file named
vmss-scale-out.yml. Insert the following code into the new file:
---
- hosts: localhost
gather_facts: false
vars:
resource_group: myTestRG
vmss_name: myTestVMSS
tasks:
- name: Get scaleset info
azure_rm_virtualmachine_scaleset_facts:
resource_group: "{{ resource_group }}"
name: "{{ vmss_name }}"
format: curated
register: output_scaleset
- name: set image fact
set_fact:
vmss_image: "{{ output_scaleset.vmss[0].image }}"
- name: Create VMSS
no_log: true
azure_rm_virtualmachinescaleset:
resource_group: "{{ resource_group }}"
name: "{{ vmss_name }}"
capacity: 3
image: "{{ vmss_image }}"
Run the playbook using ansible-playbook
ansible-playbook vmss-scale-out.yml
After running the playbook, you see output similar to the following results:
PLAY [localhost]
TASK [Gathering Facts]
ok: [localhost]
TASK [Get scaleset info]
ok: [localhost]
TASK [Set image fact]
ok: [localhost]
TASK [Change VMSS capacity]
changed: [localhost]
PLAY RECAP
localhost : ok=3 changed=1 unreachable=0 failed=0
Verify the results
Verify your results of your work via the Azure portal:
Sign in to the Azure portal.
Navigate to the scale set you configured.
You see the scale set name with the number of instances in parenthesis:
Standard_DS1_v2 (3 instances)You can also verify the change with the Azure Cloud Shell by running the following command:
az vmss show -n myScaleSet -g myResourceGroup --query '{"capacity":sku.capacity}'The results of running the Azure CLI command in Cloud Shell show that three instances now exist:
{ "capacity": 3, }