I have an application gateway with frontend public IP address, connected to a VNET via its subnet and using a single backend pool that points to a container group in the same VNET but different subnet.
The backend pool points to the IP address of the container group. That works!
But I don't want to rely on an IP address that could change anytime with the container restart. I already use a private DNS zone linked to the VNET. The container group is accessible as "mycontainer.my-azure.com" from the VNET thanks to the A record in my private DNS zone.
But putting "mycontainer.my-azure.com" as the FQDN of the backend pool does not work. It works with the IP address "172.22.44.5" but "mycontainer.my-azure.com" does not resolve, backend health shows "Unknown". I tried restarting the APP GW from AZ CLI to no avail.
Does anyone know how to make APP GW use the VNET's private DNS zone in its backend pool?
If the application gateway backend pool contains an internally resolvable FQDN or a private IP address, the application gateway routes the request to the backend server by using its instance private IP addresses. Make sure the FQDN in the backend pool can be resolved internally.
You can verify the following configuration, it works on my side. I am using the Standard V2 SKU application gateway. The application gateway and container group were deployed into the same VNet but different subnets with no firewall rules. I use this example for deploying ACI.
Backend pool
HTTP setting
Listener
Health probe
Private DNS zone
Related
I have the following situation:
If I deploy an application (Deployment, Service and Ingress) in my kubernetes cluster, my ingress deployment is being automatically added to my application gateway (I am using the Azure Application Gateway Ingress Controller; https://azure.github.io/application-gateway-kubernetes-ingress/annotations/ ). So far so good.
That means that my application can be reached via my application gateway via https://my-app-gateway-public-ip/myAppPath/. Also, I have an additional private DNS zone which makes my app accessible via https://dns-name/myAppPath.
Additionally, we have an AADDS in combination with a Bastion Service. Deployed some virtual machines and the virtual machines use the DNS resolver of the AADDS (for authentication against the AAD).
The problem is: If I am outside of the cloud, I can nslookup the dns or can access the site via the ip, but I cannot do that with my virtual machines. My DNS server (within the AADDS) is unable to resolve the dns or accessing the ip. I am wondering what the issue is.
The bastion and AADDS are in different subscriptions and therefore different virtual networks. I established already a peering between those virtual networks (or the authentication between the AADDS and the VMs wouldn't work).
The kubernetes cluster and the application gateway are also in a different subscription, but no peering has been done so far.
Are there any hints what I could be missing?
Kind regards
• Since, you are using a Bastion gateway server to connect to the VMs hosted in your subscription, the Bastion gateway server must be having a public IP address through which then the registered underlying VMs can be connected to via private links created in the private DNS zones associated with a particular virtual network in a subnet and an assigned private IP address and a FQDN accordingly. Thus, if you want to access the application website hosted behind the application gateway, then you will have to create a conditional forwarder in the DNS zone in AADDS to redirect the internal requests from the VMs hosted within a virtual network to the public IP address of the website hosted behind the application gateway
• Thus, a conditional forwarder forwards the DNS resolution requests for a particular resource hosted on the public internet for which the DNS host resolution is not found or done in that DNS zone which usually serves or fulfils the requests related to internal environment. As a result, when a VM configured with a private IP is registered as a host in the internal DNS zone queries the public IP or FQDN associated with the application’s website, the DNS requests are forwarded to the public internet through the conditional forwarder and then the results are displayed in the VM’s browser for the application’s webpage. Thus, the VMs don’t need to have internet access but the DNS server should have or should forward the requests through the Internet proxy server accordingly to reach the internet.
For more information on creating conditional forwarder in AADDS, kindly refer to the below link: -
https://learn.microsoft.com/en-us/azure/active-directory-domain-services/manage-dns#create-conditional-forwarders
I have configured my app serivce to be part of a subnet within a VNET.
Now i have integrated my app service with a private endpoint within the same VNET.
With the private endpoint integration, i'm now not able to access the app service (i.e. my API) on a public internet, where i'm getting 403 forbidden error. Which is an expected behaviour to restrict the access on the public network
But the issue is, i want to expose this API via APIM (which is internal) configured within a separate subnet in the same VNET, but i'm not not access the API now with the private endpoint IP address. I was hoping that the resources with in the VNET will be able to reach the App service using its private IP address
I also tried to configure a VM in a separate subnet with in the same VNET, but when i ping the API private IP from the VM, i'm getting request timedout.
Current there have not been any rules setup with NSG to restrict the subnets to talk between each other.
Please let me know how to expose the API with private endpoint via APIM which is also configured to be only internal
You also need to configure private dns zone as now your app's FQDN needs to be resolved to the private IP, instead of a public one.
https://learn.microsoft.com/en-us/azure/private-link/create-private-endpoint-powershell
Update:
Just want to add that app service cannot be accessed via the IP as it is assigned to the app service plan, which can be shared by other app services. The FQDN is required for app service plan to do L7 routing
I'm trying to deploy my application on Azure. Currently, I have an application gateway deployed in one subnet s1, and in the backend pool I have Linux VMs. As per the requirement, I cannot use any public ip so, I'm using only private ip on Application Gateway. Since we need the internet connection at the time of deploying application, I tried attaching NSG to the Application Gateway's subnet with inbound "Internet" allowed. When I attached the NSG to application gateway subnet, the backend health showed as unhealthy with error:
"Cannot connect to server. Check whether any NSG/UDR/Firewall is blocking access to server. Check if application is running on correct port."
I tried to add rules specified in MSFT's document https://learn.microsoft.com/en-us/azure/application-gateway/configuration-overview#allow-application-gateway-access-to-a-few-source-ips but its not helpful. So my questions are:
Is there anything more I need to add to NSG on application gateway's subnet.
Is it a good strategy to allow internet access using the inbound rule on NSG? (Inbound rule -> service tag -> Internet). Is there any other way I can have internet access just at the time of deployment? PS: I'm not allowed to use public IP at all.
Many thanks!
You can deploy Application Gateway with Public IP and Private IP. All you need to do is to create the listener with the private Frontend IP and leave the Public IP as such.
Since Public IP is not attached with any of the listener, no one will be able to access your site from Internet via Public IP of your Application Gateway.
When AppGW needs to initiate outbound to Internet, it uses that Public IP.
Note: You cannot have only Private IP as Frontend in V2 deployment and you can deploy Application Gateway with only Private Frontend IP in V1 SKU.
My health probe fails with a 403 as soon as I apply whitelisting to the App Service configured in the backend pool (I whitelist the IP that's assigned to the application gateway. IP is a standard tier and static.
Has anyone else been seeing this issue before? I was under the impression that I could whitelist the public IP assigned to the application gateway on the App Service so access is only possible from the Application Gateway endpoint.
The health probe is successful when I remove the whitelisting. So I'm sure it has something to do with that.
According to the document,
If the backend pool:
Is a public endpoint, the application gateway uses its frontend public
IP to reach the server. If there isn't a frontend public IP address,
one is assigned for the outbound external connectivity.
Contains an internally resolvable FQDN or a private IP address, the application gateway routes the request to the backend server by using
its instance private IP addresses.
Contains an external endpoint or an externally resolvable FQDN, the
application gateway routes the request to the backend server by using
its frontend public IP address. The DNS resolution is based on a
private DNS zone or custom DNS server, if configured, or it uses the
default Azure-provided DNS. If there isn't a frontend public IP
address, one is assigned for the outbound external connectivity.
Thus, you may use an internally resolvable FQDN or a private IP address of the backend app service in the backend pool.
In this case, you could change to use the default Azure app service hostname like webappname.azurewebsites.net or whitelist the internal app gateway subnet (where the application gateway instance private IP address) in the access restrictions of app service.
I have an Internal application gateway configured in Azure. There is one virtual machine in the back end pool of application gateway which hosts the application. That is accessible via Intranet only.
I want the IP address of my internal application gateway to be associated to a domain name for my website?? How can i achieve this?
If you want to use a domain name, that means the application gateway needs to have a public IP address. In the gateway settings in the Azure portal, you can add a public IP address to the frontend configuration.
Looks like you already managed to put the backend of the gateway on the virtual network, that's good.
Next, you want to create a listener on the ports you need, for example 80 or 443. This is also done on the gateway configuration in the portal.
Finally, to use a domain name, you need to take the public IP address and put it in an A-record for the domain name. This would probably be in a config page with your service provider.