Application Gateway provides an Azure-managed HTTP load balancing solution based on layer 7 load balancing. Application load balancing allows the use of routing rules for network traffic based on HTTP.
| Property | Description |
|---|---|
| backendAddressPools | The list of IP addresses of the back end servers. The IP addresses listed should either belong to the virtual network subnet, or should be a public IP/VIP or private IP |
| backendHttpSettingsCollection | Every pool has settings like port, protocol, and cookie based affinity. These settings are tied to a pool and are applied to all servers within the pool |
| frontendPorts | This port is the public port opened on the application gateway. Traffic hits this port, and then gets redirected to one of the back end servers |
| httpListeners | Listener has a frontend port, a protocol (Http or Https, these are case-sensitive), and the SSL certificate name (if configuring SSL offload) |
| requestRoutingRules | The rule binds the listener and the back end server pool and defines which back end server pool the traffic should be directed. Currently works only as Round-robin |
Example of an application gateway Json template:
{
"$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"parameters": {
"location": {
"type": "string",
"metadata": {
"description": "Location to deploy to"
}
},
"addressPrefix": {
"type": "string",
"defaultValue": "10.0.0.0/16",
"metadata": {
"description": "Address prefix for the Virtual Network"
}
},
"subnetPrefix": {
"type": "string",
"defaultValue": "10.0.0.0/28",
"metadata": {
"description": "Subnet prefix"
}
},
"skuName": {
"type": "string",
"allowedValues": [
"Standard_Small",
"Standard_Medium",
"Standard_Large"
],
"defaultValue": "Standard_Medium",
"metadata": {
"description": "Sku Name"
}
},
"capacity": {
"type": "int",
"defaultValue": 2,
"metadata": {
"description": "Number of instances"
}
},
"backendIpAddress1": {
"type": "string",
"metadata": {
"description": "IP Address for Backend Server 1"
}
},
"backendIpAddress2": {
"type": "string",
"metadata": {
"description": "IP Address for Backend Server 2"
}
}
},
"variables": {
"applicationGatewayName": "applicationGateway1",
"publicIPAddressName": "publicIp1",
"virtualNetworkName": "virtualNetwork1",
"subnetName": "appGatewaySubnet",
"vnetID": "[resourceId('Microsoft.Network/virtualNetworks',variables('virtualNetworkName'))]",
"subnetRef": "[concat(variables('vnetID'),'/subnets/',variables('subnetName'))]",
"publicIPRef": "[resourceId('Microsoft.Network/publicIPAddresses',variables('publicIPAddressName'))]",
"applicationGatewayID": "[resourceId('Microsoft.Network/applicationGateways',variables('applicationGatewayName'))]",
"apiVersion": "2015-05-01-preview"
},
"resources": [
{
"apiVersion": "[variables('apiVersion')]",
"type": "Microsoft.Network/publicIPAddresses",
"name": "[variables('publicIPAddressName')]",
"location": "[parameters('location')]",
"properties": {
"publicIPAllocationMethod": "Dynamic"
}
},
{
"apiVersion": "[variables('apiVersion')]",
"type": "Microsoft.Network/virtualNetworks",
"name": "[variables('virtualNetworkName')]",
"location": "[parameters('location')]",
"properties": {
"addressSpace": {
"addressPrefixes": [
"[parameters('addressPrefix')]"
]
},
"subnets": [
{
"name": "[variables('subnetName')]",
"properties": {
"addressPrefix": "[parameters('subnetPrefix')]"
}
}
]
}
},
{
"apiVersion": "[variables('apiVersion')]",
"name": "[variables('applicationGatewayName')]",
"type": "Microsoft.Network/applicationGateways",
"location": "[parameters('location')]",
"dependsOn": [
"[concat('Microsoft.Network/virtualNetworks/', variables ('virtualNetworkName'))]",
"[concat('Microsoft.Network/publicIPAddresses/', variables ('publicIPAddressName'))]"
],
"properties": {
"sku": {
"name": "[parameters('skuName')]",
"tier": "Standard",
"capacity": "[parameters('capacity')]"
},
"gatewayIPConfigurations": [
{
"name": "appGatewayIpConfig",
"properties": {
"subnet": {
"id": "[variables('subnetRef')]"
}
}
}
],
"frontendIPConfigurations": [
{
"name": "appGatewayFrontendIP",
"properties": {
"PublicIPAddress": {
"id": "[variables('publicIPRef')]"
}
}
}
],
"frontendPorts": [
{
"name": "appGatewayFrontendPort",
"properties": {
"Port": 80
}
}
],
"backendAddressPools": [
{
"name": "appGatewayBackendPool",
"properties": {
"BackendAddresses": [
{
"IpAddress": "[parameters('backendIpAddress1')]"
},
{
"IpAddress": "[parameters('backendIpAddress2')]"
}
]
}
}
],
"backendHttpSettingsCollection": [
{
"name": "appGatewayBackendHttpSettings",
"properties": {
"Port": 80,
"Protocol": "Http",
"CookieBasedAffinity": "Disabled"
}
}
],
"httpListeners": [
{
"name": "appGatewayHttpListener",
"properties": {
"FrontendIPConfiguration": {
"Id": "[concat(variables('applicationGatewayID'), '/ frontendIPConfigurations/appGatewayFrontendIP')]"
},
"FrontendPort": {
"Id": "[concat(variables('applicationGatewayID'), '/ frontendPorts/appGatewayFrontendPort')]"
},
"Protocol": "Http",
"SslCertificate": null
}
}
],
"requestRoutingRules": [
{
"Name": "rule1",
"properties": {
"RuleType": "Basic",
"httpListener": {
"id": "[concat(variables('applicationGatewayID'), '/ httpListeners/appGatewayHttpListener')]"
},
"backendAddressPool": {
"id": "[concat(variables('applicationGatewayID'), '/ backendAddressPools/appGatewayBackendPool')]"
},
"backendHttpSettings": {
"id": "[concat(variables('applicationGatewayID'), '/ backendHttpSettingsCollection/ appGatewayBackendHttpSettings')]"
}
}
}
]
}
}
]
}
Read application gateway REST API for more information.