Automatic OS Upgrade is not supported for this Virtual Machine Scale Set because a health probe or health extension was not specified
If you face this issue during your VMSS deployment:
- ErrorCode: DeploymentFailed
- Content: {“status”:“Failed”,“error”:{“code”:“DeploymentFailed”,“target”:"/subscriptions/YOURID/resourceGroups/vmss/providers/Microsoft.Resources/deployments/VMSS_AutomaticOsUpgrade-240328-1303",“message”:“At least one resource deployment operation failed. Please list deployment operations for details. Please see https://aka.ms/arm-deployment-operations for usage details.”,“details”:[{“code”:“BadRequest”,“message”:"Automatic OS Upgrade is not supported for this Virtual Machine Scale Set because a health probe or health extension was not specified."}]}}
It is very easy to bypass it.
If you do not have a port for your app to monitor, you can monitor management ports, like so:
Linux ARM:
{
"extensionProfile": {
"extensions": [
{
"name": "HealthExtension",
"properties": {
"publisher": "Microsoft.ManagedServices",
"type": "ApplicationHealthLinux",
"autoUpgradeMinorVersion": true,
"typeHandlerVersion": "1.0",
"settings": {
"protocol": "tcp",
"port": 22,
"intervalInSeconds": 5,
"numberOfProbes": 1
}
}
}
]
}
}
Linux Bicep:
extensionProfile: {
extensions: [
{
name: 'HealthExtension'
properties: {
publisher: 'Microsoft.ManagedServices'
type: 'ApplicationHealthLinux'
autoUpgradeMinorVersion: true
typeHandlerVersion: '1.0'
settings: {
protocol: 'tcp'
port: 22
intervalInSeconds: 5
numberOfProbes: 1
}
}
}
]
}
Windows ARM:
{
"extensionProfile": {
"extensions": [
{
"name": "HealthExtension",
"properties": {
"publisher": "Microsoft.ManagedServices",
"type": "ApplicationHealthWindows",
"autoUpgradeMinorVersion": true,
"typeHandlerVersion": "1.0",
"settings": {
"protocol": "tcp",
"port": 3389,
"intervalInSeconds": 5,
"numberOfProbes": 1
}
}
}
]
}
}
Windows Bicep:
extensionProfile: {
extensions: [
{
name: 'HealthExtension'
properties: {
publisher: 'Microsoft.ManagedServices'
type: 'ApplicationHealthWindows'
autoUpgradeMinorVersion: true
typeHandlerVersion: '1.0'
settings: {
protocol: 'tcp'
port: 3389
intervalInSeconds: 5
numberOfProbes: 1
}
}
}
]
}
The monitoring happens from within VMSS instance, so there is no need to allow those ports on firewalls:
