appGateway.cs

public void AppGateway() {
            var resourceGroup = "blah";
            var location = "Australia East";
            var netClient = new NetworkManagementClient(credential) { SubscriptionId = Lookup.subscriptionId };


            // Create IP for gateway
            var ipParams = new PublicIPAddress{Location = location ,PublicIPAllocationMethod = "Dynamic" };
            var newIp = netClient.PublicIPAddresses.CreateOrUpdate(resourceGroup, "appGatewayFrontendIP", ipParams);
            Console.WriteLine(newIp.IpAddress);

            // Get subnet Id
            var devNet = netClient.VirtualNetworks.List("blah")
                                .Where(x => x.Name.Equals("development")).FirstOrDefault();

            var tier1Subnet = devNet.Subnets.Where(sn => sn.Name.Equals("Tier1")).FirstOrDefault();

            // FrontEnd IP Config
            var frontEndIpConfig = new ApplicationGatewayFrontendIPConfiguration
            {
                
                PublicIPAddress = new SubResource { Id = newIp.Id },
                //Subnet = new SubResource { Id = tier1Subnet.Id },
                Name = "appGatewayFrontendIP"
            };

            var frontEndPort = new ApplicationGatewayFrontendPort { Name = "appGatewayFrontendPort", Port = 80 };

            var frontendIPConfigurations = new List<ApplicationGatewayFrontendIPConfiguration>() { frontEndIpConfig };
            var backEndAddressPool = new ApplicationGatewayBackendAddressPool {
                Name = "appGatewayBackendPool" ,
                BackendAddresses = new List<ApplicationGatewayBackendAddress> {  new ApplicationGatewayBackendAddress { IpAddress = "1.1.1.1" } }
            };
            var backendHttpSetting = new ApplicationGatewayBackendHttpSettings { Name= "appGatewayBackendHttpSettings", Protocol = "http", Port = 80 };
            var gatewayIpConfig = new ApplicationGatewayIPConfiguration { Name = "appGatewayIpConfig", Subnet = tier1Subnet };
            var httpListener = new ApplicationGatewayHttpListener
            {
                Name = "appGatewayHttpListener",
                FrontendIPConfiguration = frontEndIpConfig,
                FrontendPort = frontEndPort
            };
            var requestRoutingRule = new ApplicationGatewayRequestRoutingRule
            {
                Name = "rule1",
                RuleType = "Basic",
                HttpListener = httpListener,
                BackendAddressPool = backEndAddressPool,
                BackendHttpSettings = backendHttpSetting
            };

            // Create Gateway
            var parameters = new ApplicationGateway()
            {
                Location = location,
                Sku = new ApplicationGatewaySku { Name = ApplicationGatewaySkuName.StandardSmall, Capacity = 1, Tier = "Standard" },
                FrontendPorts = new List<ApplicationGatewayFrontendPort> { frontEndPort },
                FrontendIPConfigurations = frontendIPConfigurations,
                GatewayIPConfigurations = new List<ApplicationGatewayIPConfiguration> { gatewayIpConfig },
                BackendAddressPools = new List<ApplicationGatewayBackendAddressPool>() { backEndAddressPool },
                BackendHttpSettingsCollection = new List<ApplicationGatewayBackendHttpSettings>() { backendHttpSetting },
                HttpListeners = new List<ApplicationGatewayHttpListener> { httpListener },
                RequestRoutingRules = new List<ApplicationGatewayRequestRoutingRule> { requestRoutingRule}
            };

            netClient.ApplicationGateways.CreateOrUpdate(resourceGroup, "test111", parameters);
}