| title | description | services | author | ms.service | ms.topic | ms.date | ms.author | ms.custom |
|---|---|---|---|---|---|---|---|---|
Frequently asked questions about Azure Application Gateway |
Find answers to frequently asked questions about Azure Application Gateway. |
application-gateway |
vhorne |
application-gateway |
article |
05/26/2020 |
victorh |
references_regions |
[!INCLUDE updated-for-az]
The following are common questions asked about Azure Application Gateway.
Azure Application Gateway provides an application delivery controller (ADC) as a service. It offers various layer 7 load-balancing capabilities for your applications. This service is highly available, scalable, and fully managed by Azure.
Application Gateway supports autoscaling, TLS offloading, and end-to-end TLS, a web application firewall (WAF), cookie-based session affinity, URL path-based routing, multisite hosting, and other features. For a full list of supported features, see Introduction to Application Gateway.
Application Gateway is a layer 7 load balancer, which means it works only with web traffic (HTTP, HTTPS, WebSocket, and HTTP/2). It supports capabilities such as TLS termination, cookie-based session affinity, and round robin for load-balancing traffic. Load Balancer load-balances traffic at layer 4 (TCP or UDP).
Application Gateway supports HTTP, HTTPS, HTTP/2, and WebSocket.
See HTTP/2 support.
See supported backend resources.
Application Gateway v1 (Standard and WAF) is available in all regions of global Azure. It's also available in Azure China 21Vianet and Azure Government.
For Application Gateway v2 (Standard_v2 and WAF_v2) availability, see supported regions for Application Gateway v2
Application Gateway is a dedicated deployment in your virtual network.
Redirection is supported. See Application Gateway redirect overview.
See the order of listener processing.
If you're using a public IP address as an endpoint, you'll find the IP and DNS information on the public IP address resource. Or find it in the portal, on the overview page for the application gateway. If you're using internal IP addresses, find the information on the overview page.
For the v2 SKU, open the public IP resource and select Configuration. The DNS name label (optional) field is available to configure the DNS name.
Keep-Alive timeout governs how long the Application Gateway will wait for a client to send another HTTP request on a persistent connection before reusing it or closing it. TCP idle timeout governs how long a TCP connection is kept open in case of no activity.
The Keep-Alive timeout in the Application Gateway v1 SKU is 120 seconds and in the v2 SKU it's 75 seconds. The TCP idle timeout is a 4-minute default on the frontend virtual IP (VIP) of both v1 and v2 SKU of Application Gateway. You can configure the TCP idle timeout value on v1 and v2 Application Gateways to be anywhere between 4 minutes and 30 minutes. For both v1 and v2 Application Gateways, you'll need to navigate to the public IP of the Application Gateway and change the TCP idle timeout under the "Configuration" blade of the public IP on Portal. You can set the TCP idle timeout value of the public IP through PowerShell by running the following commands:
$publicIP = Get-AzPublicIpAddress -Name MyPublicIP -ResourceGroupName MyResourceGroup
$publicIP.IdleTimeoutInMinutes = "15"
Set-AzPublicIpAddress -PublicIpAddress $publicIP
In Application Gateway V1 SKU, the VIP can change if you stop and start the application gateway. But the DNS name associated with the application gateway doesn't change over the lifetime of the gateway. Because the DNS name doesn't change, you should use a CNAME alias and point it to the DNS address of the application gateway. In Application Gateway V2 SKU, you can set the IP address as static, so IP and DNS name will not change over the lifetime of the application gateway.
Yes, the Application Gateway v2 SKU supports static public IP addresses. The v1 SKU supports static internal IPs.
An application gateway supports only one public IP address.
See Application Gateway subnet size considerations.
Yes. In addition to multiple instances of a given Application Gateway deployment, you can provision another unique Application Gateway resource to an existing subnet that contains a different Application Gateway resource.
A single subnet can't support both v2 and v1 Application Gateway SKUs.
Yes, but only specific scenarios. For more information, see Application Gateway infrastructure configuration.
Yes. See Modifications to a request.
How long does it take to deploy an application gateway? Will my application gateway work while it's being updated?
New Application Gateway v1 SKU deployments can take up to 20 minutes to provision. Changes to instance size or count aren't disruptive, and the gateway remains active during this time.
Most deployments that use the v2 SKU take around 6 minutes to provision. However it can take longer depending on the type of deployment. For example, deployments across multiple Availability Zones with many instances can take more than 6 minutes.
No. Application Gateway doesn't support email protocols such as SMTP, IMAP, and POP3.
Yes. For details see, Migrate Azure Application Gateway and Web Application Firewall from v1 to v2.
Yes. The Application Gateway v1 SKU will continue to be supported. However, it is strongly recommended that you move to v2 to take advantage of the feature updates in that SKU. For more information, see Autoscaling and Zone-redundant Application Gateway v2.
No. Application Gateway V2 doesn't support proxying requests with NTLM authentication yet.
Yes, the Chromium browser v80 update introduced a mandate on HTTP cookies without SameSite attribute to be treated as SameSite=Lax. This means that the Application Gateway affinity cookie won't be sent by the browser in a third-party context.
To support this scenario, Application Gateway injects another cookie called ApplicationGatewayAffinityCORS in addition to the existing ApplicationGatewayAffinity cookie. These cookies are similar, but the ApplicationGatewayAffinityCORS cookie has two more attributes added to it: SameSite=None; Secure. These attributes maintain sticky sessions even for cross-origin requests. See the cookie based affinity section for more information.
The Application Gateway v1 SKU supports high-availability scenarios when you've deployed two or more instances. Azure distributes these instances across update and fault domains to ensure that instances don't all fail at the same time. The v1 SKU supports scalability by adding multiple instances of the same gateway to share the load.
The v2 SKU automatically ensures that new instances are spread across fault domains and update domains. If you choose zone redundancy, the newest instances are also spread across availability zones to offer zonal failure resiliency.
Use Traffic Manager to distribute traffic across multiple application gateways in different datacenters.
Yes, the Application Gateway v2 SKU supports autoscaling. For more information, see Autoscaling and Zone-redundant Application Gateway.
No. Instances are distributed across upgrade domains and fault domains.
Yes. You can set up connection draining to change members within a backend pool without disruption. For more information, see connection draining section of Application Gateway.
Yes.
Yes. Application Gateway is always deployed in a virtual network subnet. This subnet can contain only application gateways. For more information, see virtual network and subnet requirements.
Can Application Gateway communicate with instances outside of its virtual network or outside of its subscription?
As long as you have IP connectivity, Application Gateway can communicate with instances outside of the virtual network that it's in. Application Gateway can also communicate with instances outside of the subscription it's in. If you plan to use internal IPs as backend pool members, use virtual network peering or Azure VPN Gateway.
No. But you can deploy other application gateways in the subnet.
See Network security groups in the Application Gateway subnet.
See User-defined routes supported in the Application Gateway subnet.
No. Service endpoint policies for storage accounts are not supported in Application Gateway subnet and configuring it will block Azure infrastructure traffic.
See Application Gateway limits.
Yes. Application Gateway supports one internal IP and one external IP per application gateway.
Yes. Virtual network peering helps load-balance traffic in other virtual networks.
Yes, as long as traffic is allowed.
Microservice architecture is supported. To probe on different ports, you need to configure multiple HTTP settings.
No.
See Order of processing rules.
The Host field specifies the name to send the probe to when you've configured multisite on Application Gateway. Otherwise use '127.0.0.1'. This value is different from the virtual machine host name. Its format is <protocol>://<host>:<port><path>.
Yes. See restrict access to specific source IPs.
No.
Application Gateway v2 does not currently support IPv6. It can operate in a dual stack VNet using only IPv4, but the gateway subnet must be IPv4-only. Application Gateway v1 does not support dual stack VNets.
Application Gateway V2 currently does not support only private IP mode. It supports the following combinations
- Private IP and Public IP
- Public IP only
But if you'd like to use Application Gateway V2 with only private IP, you can follow the process below:
-
Create an Application Gateway with both public and private frontend IP address
-
Do not create any listeners for the public frontend IP address. Application Gateway will not listen to any traffic on the public IP address if no listeners are created for it.
-
Create and attach a Network Security Group for the Application Gateway subnet with the following configuration in the order of priority:
a. Allow traffic from Source as GatewayManager service tag and Destination as Any and Destination port as 65200-65535. This port range is required for Azure infrastructure communication. These ports are protected (locked down) by certificate authentication. External entities, including the Gateway user administrators, can't initiate changes on those endpoints without appropriate certificates in place
b. Allow traffic from Source as AzureLoadBalancer service tag and Destination and destination port as Any
c. Deny all inbound traffic from Source as Internet service tag and Destination and destination port as Any. Give this rule the least priority in the inbound rules
d. Keep the default rules like allowing VirtualNetwork inbound so that the access on private IP address is not blocked
e. Outbound internet connectivity can't be blocked. Otherwise, you will face issues with logging, metrics, etc.
Sample NSG configuration for private IP only access:
Application Gateway supports self-signed certificates, certificate authority (CA) certificates, Extended Validation (EV) certificates, multi-domain (SAN) certificates, and wildcard certificates.
Application Gateway supports the following cipher suites.
- TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
- TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
- TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384
- TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256
- TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
- TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA
- TLS_DHE_RSA_WITH_AES_256_GCM_SHA384
- TLS_DHE_RSA_WITH_AES_128_GCM_SHA256
- TLS_DHE_RSA_WITH_AES_256_CBC_SHA
- TLS_DHE_RSA_WITH_AES_128_CBC_SHA
- TLS_RSA_WITH_AES_256_GCM_SHA384
- TLS_RSA_WITH_AES_128_GCM_SHA256
- TLS_RSA_WITH_AES_256_CBC_SHA256
- TLS_RSA_WITH_AES_128_CBC_SHA256
- TLS_RSA_WITH_AES_256_CBC_SHA
- TLS_RSA_WITH_AES_128_CBC_SHA
- TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384
- TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
- TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384
- TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256
- TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA
- TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA
- TLS_DHE_DSS_WITH_AES_256_CBC_SHA256
- TLS_DHE_DSS_WITH_AES_128_CBC_SHA256
- TLS_DHE_DSS_WITH_AES_256_CBC_SHA
- TLS_DHE_DSS_WITH_AES_128_CBC_SHA
- TLS_RSA_WITH_3DES_EDE_CBC_SHA
- TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA
For information on how to customize TLS options, see Configure TLS policy versions and cipher suites on Application Gateway.
Yes. Application Gateway supports TLS offload and end-to-end TLS, which reencrypt traffic to the backend.
Yes. You can configure Application Gateway to deny TLS1.0, TLS1.1, and TLS1.2. By default, SSL 2.0 and 3.0 are already disabled and aren't configurable.
Yes. In Application Gateway, you can configure cipher suites. To define a custom policy, enable at least one of the following cipher suites.
- TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
- TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256
- TLS_DHE_RSA_WITH_AES_128_GCM_SHA256
- TLS_RSA_WITH_AES_128_GCM_SHA256
- TLS_RSA_WITH_AES_256_CBC_SHA256
- TLS_RSA_WITH_AES_128_CBC_SHA256
Application Gateway uses SHA256 to for backend management.
Application Gateway supports up to 100 TLS/SSL certificates.
Application Gateway supports up to 100 authentication certificates.
Yes, the Application Gateway v2 SKU supports Key Vault. For more information, see TLS termination with Key Vault certificates.
For multiple domain-based (host-based) routing, you can create multisite listeners, set up listeners that use HTTPS as the protocol, and associate the listeners with the routing rules. For more information, see Hosting multiple sites by using Application Gateway.
No, use only alphanumeric characters in your .pfx file password.
My EV certificate is issued by DigiCert and my intermediate certificate has been revoked. How do I renew my certificate on Application Gateway?
Certificate Authority (CA) Browser members recently published reports detailing multiple certificates issued by CA vendors that are used by our customers, Microsoft, and the greater technology community that were out of compliance with industry standards for publicly trusted CAs. The reports regarding the non-compliant CAs can be found here:
As per the industry’s compliance requirements, CA vendors began revoking non-compliant CAs and issuing compliant CAs which requires customers to have their certificates re-issued. Microsoft is partnering closely with these vendors to minimize the potential impact to Azure Services, however your self-issued certificates or certificates used in “Bring Your Own Certificate” (BYOC) scenarios are still at risk of being unexpectedly revoked.
To check if certificates utilized by your application have been revoked reference DigiCert’s Announcement and the Certificate Revocation Tracker. If your certificates have been revoked, or will be revoked, you will need to request new certificates from the CA vendor utilized in your applications. To avoid your application’s availability being interrupted due to certificates being unexpectedly revoked, or to update a certificate which has been revoked, please refer to our Azure updates post for remediation links of various Azure services that support BYOC: https://azure.microsoft.com/updates/certificateauthorityrevocation/
For Application Gateway specific information, see below -
If you are using a certificate issued by one of the revoked ICAs, your application’s availability might be interrupted and depending on your application, you may receive a variety of error messages including but not limited to:
- Invalid certificate/revoked certificate
- Connection timed out
- HTTP 502
To avoid any interruption to your application due to this issue, or to re-issue a CA which has been revoked, you need to take the following actions:
- Contact your certificate provider on how to re-issue your certificates
- Once reissued, update your certificates on the Azure Application Gateway/WAF with the complete chain of trust (leaf, intermediate, root certificate). Based on where you are using your certificate, either on the listener or the HTTP settings of the Application Gateway, follow the steps below to update the certificates and check the documentation links mentioned for more information.
- Update your backend application servers to use the re-issued certificate. Depending on the backend server that you are using, your certificate update steps may vary. Please check for the documentation from your vendor.
To update the certificate in your listener:
- In the Azure portal, open your Application Gateway resource
- Open the listener settings that’s associated with your certificate
- Click “Renew or edit selected certificate”
- Upload your new PFX certificate with the password and click Save
- Access the website and verify if the site is working as expected For more information, check documentation here.
If you are referencing certificates from Azure KeyVault in your Application Gateway listener, we recommend the following the steps for a quick change –
- In the Azure portal, navigate to your Azure KeyVault settings which has been associated with the Application Gateway
- Add/import the reissued certificate in your store. See documentation here for more information on how-to.
- Once the certificate has been imported, navigate to your Application Gateway listener settings and under “Choose a certificate from Key Vault”, click on the “Certificate” drop down and choose the recently added certificate
- Click Save For more information on TLS termination on Application Gateway with Key Vault certificates, check documentation here.
To update the certificate in your HTTP Settings:
If you are using V1 SKU of the Application Gateway/WAF service, then you would have to upload the new certificate as your backend authentication certificate.
- In the Azure portal, open your Application Gateway resource
- Open the HTTP settings that’s associated with your certificate
- Click on “Add certificate” and upload the reissued certificate and click save
- You can remove the old certificate later by clicking on the “…” options button next to the old certificate and select delete and click save. For more information, check documentation here.
If you are using the V2 SKU of the Application Gateway/WAF service, you don’t have to upload the new certificate in the HTTP settings since V2 SKU uses “trusted root certificates” and no action needs to be taken here.
Kubernetes allows creation of deployment and service resource to expose a group of pods internally in the cluster. To expose the same service externally, an Ingress resource is defined which provides load balancing, TLS termination and name-based virtual hosting.
To satisfy this Ingress resource, an Ingress Controller is required which listens for any changes to Ingress resources and configures the load balancer policies.
The Application Gateway Ingress Controller (AGIC) allows Azure Application Gateway to be used as the ingress for an Azure Kubernetes Service also known as an AKS cluster.
Currently, one instance of Ingress Controller can only be associated to one Application Gateway.
AGIC tries to automatically associate the route table resource to the Application Gateway subnet but may fail to do so due to lack of permissions from the AGIC. If AGIC is unable to associate the route table to the Application Gateway subnet, there will be an error in the AGIC logs saying so, in which case you'll have to manually associate the route table created by the AKS cluster to the Application Gateway's subnet. For more information, see Supported user-defined routes.
Yes, as long as the virtual networks are peered and they don't have overlapping address spaces. If you're running AKS with kubenet, then be sure to associate the route table generated by AKS to the Application Gateway subnet.
Please see the differences between AGIC deployed through Helm versus deployed as an AKS add-on here
Please see the differences between AGIC deployed through Helm versus deployed as an AKS add-on here, especially the tables documenting which scenario(s) are supported by AGIC deployed through Helm as opposed to an AKS add-on. In general, deploying through Helm will allow you to test out beta features and release candidates before an official release.
No, AGIC add-on is a managed service which means Microsoft will automatically update the add-on to the latest stable version.
Application Gateway provides three logs:
- ApplicationGatewayAccessLog: The access log contains each request submitted to the application gateway frontend. The data includes the caller's IP, URL requested, response latency, return code, and bytes in and out. It contains one record per application gateway.
- ApplicationGatewayPerformanceLog: The performance log captures performance information for each application gateway. Information includes the throughput in bytes, total requests served, failed request count, and healthy and unhealthy backend instance count.
- ApplicationGatewayFirewallLog: For application gateways that you configure with WAF, the firewall log contains requests that are logged through either detection mode or prevention mode.
All logs are collected every 60 seconds. For more information, see Backend health, diagnostics logs, and metrics for Application Gateway.
Verify health by using the PowerShell cmdlet Get-AzApplicationGatewayBackendHealth or the portal. For more information, see Application Gateway diagnostics.
Diagnostic logs flow to the customer's storage account. Customers can set the retention policy based on their preference. Diagnostic logs can also be sent to an event hub or Azure Monitor logs. For more information, see Application Gateway diagnostics.
In the portal, on the menu blade of an application gateway, select Activity Log to access the audit log.
Yes. In Application Gateway, alerts are configured on metrics. For more information, see Application Gateway metrics and Receive alert notifications.
You can view and analyze access logs in several ways. Use Azure Monitor logs, Excel, Power BI, and so on.
You can also use a Resource Manager template that installs and runs the popular GoAccess log analyzer for Application Gateway access logs. GoAccess provides valuable HTTP traffic statistics such as unique visitors, requested files, hosts, operating systems, browsers, and HTTP status codes. For more information, in GitHub, see the Readme file in the Resource Manager template folder.
Usually, you see an unknown status when access to the backend is blocked by a network security group (NSG), custom DNS, or user-defined routing (UDR) on the application gateway subnet. For more information, see Backend health, diagnostics logging, and metrics for Application Gateway.
Yes. If your configuration matches following scenario, you won't see allowed traffic in your NSG flow logs:
- You've deployed Application Gateway v2
- You have an NSG on the application gateway subnet
- You've enabled NSG flow logs on that NSG
To learn more about Application Gateway, see What is Azure Application Gateway?.