Is it possible to assign public static IPs to individual VMs in Azure VMSS?

Question

There is a document describing how to allocate a public IP per VM in VMSS: https://learn.microsoft.com/en-us/azure/virtual-machine-scale-sets/virtual-machine-scale-sets-networking#public-ipv4-per-virtual-machine

But it is not clear how to assign public static IP per VM. Is it possible?

Answer 1

Unfortunately, Azure does not provide control of the Public IP allocation method per instance in VMSS. You can see the all supported Properties of VirtualMachineScaleSetPublicIPAddressConfigurationProperties object in the latest ARM API version.

However, after my validation, when you restart the instance or VMSS scale-in or scale-out, the public IP address of existing instances is not changed. The public IP address of instances will be updated unless you stop the instance of VMSS.

Update

Currently, you can manage it with IpPublicPrefix. Note that IpPublicPrefix requires a standard SKU load balancer and public IP address. Here is a working sample. You can check the public IP address of the instances in VMSS with the REST API.

{
    "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
    "contentVersion": "1.0.0.0",
    "parameters": {
        "vmSku": {
            "type": "string",
            "defaultValue": "Standard_A1_v2",
            "metadata": {
                "description": "Size of VMs in the VM Scale Set."
            }
        },
        "windowsOSVersion": {
            "type": "string",
            "defaultValue": "2019-Datacenter",
            "allowedValues": [
                "2008-R2-SP1",
                "2012-Datacenter",
                "2012-R2-Datacenter",
                "2016-Datacenter",
                "2019-Datacenter"
            ],
            "metadata": {
                "description": "The Windows version for the VM. This will pick a fully patched image of this given Windows version. Allowed values: 2008-R2-SP1, 2012-Datacenter, 2012-R2-Datacenter & 2016-Datacenter, 2019-Datacenter."
            }
        },
        "vmssName": {
            "type": "string",
            "minLength": 3,
            "maxLength": 61,
            "metadata": {
                "description": "String used as a base for naming resources. Must be 3-61 characters in length and globally unique across Azure. A hash is prepended to this string for some resources, and resource-specific information is appended."
            }
        },
        "instanceCount": {
            "type": "int",
            "defaultValue": 3,
            "minValue": 1,
            "maxValue": 100,
            "metadata": {
                "description": "Number of VM instances (100 or less)."
            }
        },
        "singlePlacementGroup": {
            "type": "bool",
            "defaultValue": true,
            "metadata": {
                "description": "When true this limits the scale set to a single placement group, of max size 100 virtual machines. NOTE: If singlePlacementGroup is true, it may be modified to false. However, if singlePlacementGroup is false, it may not be modified to true."
            }
        },
        "adminUsername": {
            "type": "string",
            "defaultValue": "vmssadmin",
            "metadata": {
                "description": "Admin username on all VMs."
            }
        },
        "adminPassword": {
            "type": "securestring",
            "metadata": {
                "description": "Admin password on all VMs."
            }
        },
        
        "location": {
            "type": "string",
            "defaultValue": "[resourceGroup().location]",
            "metadata": {
                "description": "Location for all resources."
            }
        },
        "platformFaultDomainCount": {
            "type": "int",
            "defaultValue": 1,
            "metadata": {
                "description": "Fault Domain count for each placement group."
            }
        },
        "publicIPPrefixes_pubprefix_name": {
            "defaultValue": "vmsspublicprefix",
            "type": "string"
        }
    },
    "variables": {
        "namingInfix": "[toLower(substring(concat(parameters('vmssName'), uniqueString(resourceGroup().id)), 0, 9))]",
        "longNamingInfix": "[toLower(parameters('vmssName'))]",
        "addressPrefix": "10.0.0.0/16",
        "subnetPrefix": "10.0.0.0/24",
        "virtualNetworkName": "[concat(variables('namingInfix'), 'vnet')]",
        "publicIPAddressName": "[concat(variables('namingInfix'), 'pip')]",
        "subnetName": "[concat(variables('namingInfix'), 'subnet')]",
        "loadBalancerName": "[concat(variables('namingInfix'), 'lb')]",
        "publicIPAddressID": "[resourceId('Microsoft.Network/publicIPAddresses',variables('publicIPAddressName'))]",
        "lbProbeID": "[resourceId('Microsoft.Network/loadBalancers/probes',variables('loadBalancerName'), 'tcpProbe')]",
        "natPoolName": "[concat(variables('namingInfix'), 'natpool')]",
        "bePoolName": "[concat(variables('namingInfix'), 'bepool')]",
        "lbPoolID": "[resourceId('Microsoft.Network/loadBalancers/backendAddressPools',variables('loadBalancerName'),variables('bePoolName'))]",
        "natStartPort": 50000,
        "natEndPort": 50119,
        "natBackendPort": 3389,
        "nicName": "[concat(variables('namingInfix'), 'nic')]",
        "ipConfigName": "[concat(variables('namingInfix'), 'ipconfig')]",
        "frontEndIPConfigID": "[resourceId('Microsoft.Network/loadBalancers/frontendIPConfigurations',variables('loadBalancerName'),'loadBalancerFrontEnd')]",
        "osType": {
            "publisher": "MicrosoftWindowsServer",
            "offer": "WindowsServer",
            "sku": "[parameters('windowsOSVersion')]",
            "version": "latest"
        },
        "imageReference": "[variables('osType')]"

    },
    "resources": [
        {
            "type": "Microsoft.Network/loadBalancers",
            "apiVersion": "2020-06-01",
            "name": "[variables('loadBalancerName')]",
            "location": "[parameters('location')]",
            "dependsOn": [
                "[resourceId('Microsoft.Network/publicIPAddresses', variables('publicIPAddressName'))]"
            ],
            "sku": {
                   "name": "Standard"
                  },
            "properties": {
                "frontendIPConfigurations": [
                    {
                        "name": "LoadBalancerFrontEnd",
                        "properties": {
                            "publicIPAddress": {
                                "id": "[variables('publicIPAddressID')]",
                                "name": "Standard"
                            }
                        }
                    }
                ],
                "backendAddressPools": [
                    {
                        "name": "[variables('bePoolName')]"
                    }
                ],
                "inboundNatPools": [
                    {
                        "name": "[variables('natPoolName')]",
                        "properties": {
                            "frontendIPConfiguration": {
                                "id": "[variables('frontEndIPConfigID')]"
                            },
                            "protocol": "Tcp",
                            "frontendPortRangeStart": "[variables('natStartPort')]",
                            "frontendPortRangeEnd": "[variables('natEndPort')]",
                            "backendPort": "[variables('natBackendPort')]"
                        }
                    }
                ],
                "loadBalancingRules": [
                    {
                        "name": "LBRule",
                        "properties": {
                            "frontendIPConfiguration": {
                                "id": "[variables('frontEndIPConfigID')]"
                            },
                            "backendAddressPool": {
                                "id": "[variables('lbPoolID')]"
                            },
                            "protocol": "Tcp",
                            "frontendPort": 80,
                            "backendPort": 80,
                            "enableFloatingIP": false,
                            "idleTimeoutInMinutes": 5,
                            "probe": {
                                "id": "[variables('lbProbeID')]"
                            }
                        }
                    }
                ],
                "probes": [
                    {
                        "name": "tcpProbe",
                        "properties": {
                            "protocol": "Tcp",
                            "port": 80,
                            "intervalInSeconds": 5,
                            "numberOfProbes": 2
                        }
                    }
                ]
            }
        },

        {
            "type": "Microsoft.Network/publicIPPrefixes",
            "apiVersion": "2020-11-01",
            "name": "[parameters('publicIPPrefixes_pubprefix_name')]",
            "location": "[parameters('location')]",
            "sku": {
                "name": "Standard",
                "tier": "Regional"
            },
            "properties": {
                "prefixLength": 28,
                "publicIPAddressVersion": "IPv4",
                "ipTags": []
            }
        },
        {
            "type": "Microsoft.Compute/virtualMachineScaleSets",
            "apiVersion": "2020-06-01",
            "name": "[variables('namingInfix')]",
            "location": "[parameters('location')]",
            "sku": {
                "name": "[parameters('vmSku')]",
                "tier": "Standard",
                "capacity": "[parameters('instanceCount')]"
            },
            "dependsOn": [
                "[resourceId('Microsoft.Network/loadBalancers', variables('loadBalancerName'))]",
                "[resourceId('Microsoft.Network/virtualNetworks', variables('virtualNetworkName'))]",
                "[resourceId('Microsoft.Network/publicIPPrefixes',parameters('publicIPPrefixes_pubprefix_name'))]"
            ],
            "properties": {
                "overprovision": true,
                "upgradePolicy": {
                    "mode": "Automatic"
                },
                "singlePlacementGroup": "[parameters('singlePlacementGroup')]",
                "platformFaultDomainCount": "[parameters('platformFaultDomainCount')]",
                "virtualMachineProfile": {
                    "storageProfile": {
                        "osDisk": {
                            "caching": "ReadWrite",
                            "createOption": "FromImage"
                        },
                        "imageReference": "[variables('imageReference')]"
                    },
                    "osProfile": {
                        "computerNamePrefix": "[variables('namingInfix')]",
                        "adminUsername": "[parameters('adminUsername')]",
                        "adminPassword": "[parameters('adminPassword')]"
                    },
                    "networkProfile": {
                        "networkInterfaceConfigurations": [
                            {
                                "name": "[variables('nicName')]",
                                "properties": {
                                    "primary": true,
                                    "ipConfigurations": [
                                        {
                                            "name": "[variables('ipConfigName')]",
                                            "properties": {
                                                "subnet": {
                                                    "id": "[resourceId('Microsoft.Network/virtualNetworks/subnets', variables('virtualNetworkName'), variables('subnetName'))]"
                                                },
                                                "loadBalancerBackendAddressPools": [
                                                    {
                                                        "id": "[variables('lbPoolID')]"
                                                    }
                                                ],
                                                "loadBalancerInboundNatPools": [
                                                    {
                                                        "id": "[resourceId('Microsoft.Network/loadBalancers/inboundNatPools', variables('loadBalancerName'),  variables('natPoolName'))]"
                                                    }
                                                ],

                                                    "publicipaddressconfiguration": {
                                                        "name": "pub1",
                                                        "properties": {
                                                            "idleTimeoutInMinutes": 15,
                                                        "publicIPAddressVersion": "IPv4",
                                                        "publicIPPrefix":{
                                                            "id": "[resourceId('Microsoft.Network/publicIPPrefixes',parameters('publicIPPrefixes_pubprefix_name'))]"
                                                        }
                                                        }
                                                                    
                                                    }

                                            }


                                        }
                                    ]
                                }
                            }
                        ]
                    }

                }
            }
        },
        {
            "type": "Microsoft.Network/publicIPAddresses",
            "apiVersion": "2020-06-01",
            "name": "[variables('publicIPAddressName')]",
            "location": "[parameters('location')]",
              "sku": {
                    "name": "Standard"      
                },
            "properties": {
                "publicIPAllocationMethod": "Static",
                "dnsSettings": {
                    "domainNameLabel": "[variables('longNamingInfix')]"
                }
            }
        },
        {
            "type": "Microsoft.Network/virtualNetworks",
            "apiVersion": "2020-06-01",
            "name": "[variables('virtualNetworkName')]",
            "location": "[parameters('location')]",
            "properties": {
                "addressSpace": {
                    "addressPrefixes": [
                        "[variables('addressPrefix')]"
                    ]
                },
                "subnets": [
                    {
                        "name": "[variables('subnetName')]",
                        "properties": {
                            "addressPrefix": "[variables('subnetPrefix')]"
                        }
                    }
                ]
            }
        },
        {
            "type": "Microsoft.Insights/autoscaleSettings",
            "apiVersion": "2015-04-01",
            "name": "autoscalehost",
            "location": "[parameters('location')]",
            "dependsOn": [
                "[resourceId('Microsoft.Compute/virtualMachineScaleSets/', variables('namingInfix'))]"
            ],
            "properties": {
                "name": "autoscalehost",
                "targetResourceUri": "[resourceId('Microsoft.Compute/virtualMachineScaleSets', variables('namingInfix'))]",
                "enabled": true,
                "profiles": [
                    {
                        "name": "Profile1",
                        "capacity": {
                            "minimum": "1",
                            "maximum": "10",
                            "default": "1"
                        },
                        "rules": [
                            {
                                "metricTrigger": {
                                    "metricName": "Percentage CPU",
                                    "metricResourceUri": "[resourceId('Microsoft.Compute/virtualMachineScaleSets', variables('namingInfix'))]",
                                    "timeGrain": "PT1M",
                                    "statistic": "Average",
                                    "timeWindow": "PT5M",
                                    "timeAggregation": "Average",
                                    "operator": "GreaterThan",
                                    "threshold": 50
                                },
                                "scaleAction": {
                                    "direction": "Increase",
                                    "type": "ChangeCount",
                                    "value": "1",
                                    "cooldown": "PT5M"
                                }
                            },
                            {
                                "metricTrigger": {
                                    "metricName": "Percentage CPU",
                                    "metricResourceUri": "[resourceId('Microsoft.Compute/virtualMachineScaleSets', variables('namingInfix'))]",
                                    "timeGrain": "PT1M",
                                    "statistic": "Average",
                                    "timeWindow": "PT5M",
                                    "timeAggregation": "Average",
                                    "operator": "LessThan",
                                    "threshold": 30
                                },
                                "scaleAction": {
                                    "direction": "Decrease",
                                    "type": "ChangeCount",
                                    "value": "1",
                                    "cooldown": "PT5M"
                                }
                            }
                        ]
                    }
                ]
            }
        }
    ]

}