Azure Update Management - Schedule VM patching with tags

This repo is a set of Runbooks that allows you to schedule Azure Virtual Machines patching by simply applying the POLICY_UPDATE tag on machines.

• Azure Update Management - Schedule VM patching with tags
• Global Picture
  • POLICY_UPDATE syntax
  • Features
  • Unsupported scenarios
  • Runbooks description
  • Limitations
• Getting started
  • Quick deployment (for testing purpose)
  • Production Deployment & Recommendations
• Authors

Global Picture

Shared Runbooks need the following initial bricks to work:

• A Log Analytics Workspace
• An Automation Account linked to the Log Analytics Workspace
  • The Automation account must use a System-assigned Managed Identity
  • The System-assigned Managed Identity must have Contributor role
    • assigned on all subscriptions where machines (Azure VMs or Azure Arc Servers) can be found
    • assigned to the Resource Group where the Automation Account is located
• Machines that need to be patched must have:
  • Log Analytics Agent Extension installed, and linked to the Log Analytics Workspace
  • POLICY_UPDATE key tag declared with appropriated value

POLICY_UPDATE syntax

Here is the syntax to follow for the POLICY_UPDATE tag:

Examples:

• VM1 - POLICY_UPDATE=Friday;10:00 PM;Never;*java*; will be patched every Friday, at 10:00 PM. Even if updates require reboot, the VM will not be rebooted. Packages containing java string will be excluded.
• VM2 - POLICY_UPDATE=Tuesday,Sunday;08:00 AM;IfRequired;;[email protected] will be patched every Tuesday and Sunday, at 08:00 AM. The VM will be rebooted only if a patch needs the machine to be reboot to be taken into account. No excluded packages. When patching is done, [email protected] will receive the list of updated packages by mail.
• VM3 - POLICY_UPDATE=Sunday;07:00 PM;Always;; will be patched every Synday at 07:00 PM. The VM will be rebooted after applying patches, even if it is not required. No excluded packages.
• VM4 - POLICY_UPDATE=Monday;01:00 PM;Always;*java*,*oracle*;[email protected] will be patched every Monday at 01:00 PM. The VM will be rebooted after applying patches. Packages containing java or oracle string will be excluded. When patching is done, [email protected] will receive the list of updated packages by mail.

Features

Shared Runbooks allows you to:

• Patch Azure Virtual Machines and Azure Arc Servers with Supported OS
• Patch in a multi-subscriptions context: the system-assigned managed identity must have Contributor role assigned on each subscription.
• Perform several pre and post patching tasks:
  • Pre scripts, before patching:
    • [OPTIONAL] Snapshot VM OS disk
    • [OPTIONAL] Start VM if it is stopped
  • Post scripts, after patching:
    • [OPTIONAL] Shutdown VM if it was started by pre-script.
    • [OPTIONAL] Send a patching report email
• Support Azure Arc Server
  • Pre-scripts and post scripts are not supported for Azure Arc Servers
    • You can schedule Azure Arc Servers restarts using POLICY_RESTART tag with Runbooks available in this repo

Unsupported scenarios

Below Azure Resource cannot be patched by Azure Update Management:

• VMSS: Leverage automatic OS image upgrade instead.
• AVD: Leverage automatic updates instead.
• AKS: Leverage auto-upgrade channel and planned-maintenance instead.

Runbooks description

There is a set of 5 Runbooks that must be deployed in the Automation Account:

• UM-ScheduleUpdatesWithVmsTags: Must be scheduled (at least) daily. Searches for all machines with the POLICY_UPDATE tag and configures the Update Management schedules.
• UM-PreTasks: Triggered before patching, it can perform several optional actions like OS disk snapshot, start VM if stopped, etc..
• UM-PostTasks: Triggered after patching, it can perform several optional actions like stop VM if it was started, send patching report mail, etc..
• UM-CleanUp-Snapshots: Must be scheduled daily, to delete snapshots that are X days older.
• UM-CleanUp-Schedules: Must be schedule (at least) daily. It removes Update Management schedules for VM machines that not longer have the POLICY_UPDATE tag

Prerequisites

Automation Account must have the following modules installed:

• Az.ResourceGraph, >= 0.11.0
• Az.ConnectedMachine >= 0.2.0
• Az.Automation >= 1.7.1
• Az.Compute >= 4.17.1

Note: Runbooks must be deployed using Powershell Runtime v5.1

Limitations

• VMs must have a unique name. It is not possible to have several VMs with the same name using POLICY_UPDATE tag.
• A VM must be part of a single schedule. If it is not the case, UM-CleanUp-Schedules has side effects.
• When the POLICY_UPDATE tag is applied, the first patching can be done the day after the execution of UM-ScheduleUpdatesWithVmsTags.

Getting started

Quick deployment (for testing purpose)

To quickly test provided Runbooks, use the provided bicep script to deploy a complete testing infrastructure that will:

• Deploy a Log Analytics Workspace
• Deploy an Automation Account using a System-assigned Magaged Identity
  • Install Update Management solution
  • Assign Contributor role on the System-assigned Managed Identity to the Resource Group
• Deploy 5 Runbooks to the Automation Accounts and schedule few of them
• Deploy 1 VNet
• Deploy 6 VMs (3 Windows, 3 Linux) in the VNet
  • with Log Analytics agent installed and plugged to the Log Analytics Workspace
  • with POLICY_UPDATE tag examples
• If you want to receive a mail report, 2 variables in the Automation Account needs to be defined :
  • SendGridAPIKey (type: secure string): API access key provided by SendGrid to use your account
  • SendGridSender (type: string): Sender email address (from) configured on SendGrid

Here is a partial screenshot of deployed resources:

Quick start:

• Prerequisites:

# Create a resource group
$ az group create --location westeurope --name MyRg

$ git clone https://github.com/dawlysd/azure-update-management-with-tags.git
...
$ cd azure-update-management-with-tags/bicep

• Deploy without email feature:

$ az deployment group create --resource-group MyRg --template-file main.bicep

If you want to enable patching report email feature later, just update SendGridSender and SendGridAPIKey Automation Account variables.

• Deploy with email feature:

$ az deployment group create --resource-group MyRg --template-file main.bicep --parameters SendGridSender="[email protected]" SendGridAPIKey="SG.XXXXXXXXXXXXX-XXXXXXXXXXXXXXXXXXX-XXXXXXXXXXXXXXXXXXXXXXXX"

Infrastructure deployment will take around 5 minutes and it can take until 20 minutes to have update agent ready and first patching assessment.

Production Deployment & Recommendations

For scaling up of this model in production, we recommend:

• Minimize the number of Log analytics workspace and Automation Account.
  • Option 1: Using a single log analytics workspace and a single automation account. Provided runbooks support this option.
  • Option 2: Having one log analytics workspace and one automation account per geo. Provided runbooks must be updated to adopt this option.
• Leverage Policies to install Log Analytics agent on VMs
  • Built-in Deploy Log Analytics agent for Linux VMs
  • Built-in Deploy - Configure Log Analytics agent to be enabled on Windows virtual machines
• Track all unpatched VMs with UM (due to incompatible OS…)

Authors

Vincent Misson & David Santiago