I'm configuring Azure Application Gateway Url based routing for my two back-end pools and it is not working.
My default routing configuration is pointing to b1 end point and it is reachable by blabla.cloudapp.azure.com
When I add additional route path /b1/* I cannot access my back-end pool via blabla.cloudapp.azure.com/b1/. I get 404 page not found response.
Can anyone please help me to understand what is wrong with my configuration?
Azure Application Gateway URL Based routing will route different requests to different groups of servers (backend pools) based upon the URL of the request. Once the request is sent to a VM, it is received and treated like a normal web request. If the URL you are accessing is a Valid web URL for the web server that is receiving the request, then it will return a proper response.
The fact that you are getting a 404 error means that your web servers are receiving the request, but not finding anything at the requested location. One way you can troubleshoot this is to log onto the VM that should be receiving the request and trying the request in a browser replacing blabla.cloudapp.azure.com/with localhost/.
In the example you posted, you would need a folder from within your web directory called "b1" for the URL you specified to be a valid request.
You can use a Path-Based Rule to specify the default backend pool, as well as specific URL paths that should be sent to other backend pools. Here is an example of how to configure a Azure Application Gateway with URL based routing in the Portal.
Related
Is it possible to include a separate Azure App Service as part of another App Service?
For example lets say that I have a website called www.mycompany.com hosted in its own Azure App Service. I have another Azure App Service that I want to make it accessible by going to a specific URL in the first App Service.
So in other words when a request comes to www.mycompany.com/eu/ I want the content of this endpoint (/eu) to be served from the other app service. Would a load balancer work? The reason I want to do this is because the /eu endpoint has grown too big and I would like to separate that from the main site and host it on a separate app service. I hope my question is clear.
Thanks in advance.
For this purpose you could use Application Gateway.
In a certain sense it resembles a load balancer (it is a L7 LB indeed) as you indicated, but the product provides many additional features.
The following image, extracted from the product documentation, explains how it works:
Basically, as outlined in the aforementioned docs, when describing how an Application Gateway accepts a request (note they mention WAF in the explanation, an optional security threat prevention system):
Before a client sends a request to an application gateway, it
resolves the domain name of the application gateway by using a Domain
Name System (DNS) server. Azure controls the DNS entry because all
application gateways are in the azure.com domain.
The Azure DNS returns the IP address to the client, which is the
frontend IP address of the application gateway.
The application gateway accepts incoming traffic on one or more
listeners. A listener is a logical entity that checks for
connection requests. It's configured with a frontend IP address,
protocol, and port number for connections from clients to the
application gateway.
If a web application firewall (WAF) is in use, the application
gateway checks the request headers and the body, if present,
against WAF rules. This action determines if the request is valid
request or a security threat. If the request is valid, it's routed
to the backend. If the request isn't valid and WAF is in Prevention
mode, it's blocked as a security threat. If it's in Detection mode,
the request is evaluated and logged, but still forwarded to the
backend server.
The routing to one backend or another can be based on URL Paths:
You can find an example of this configuration in this related Microsoft article.
In your use case, you will need to define two backends, one for every App Service, and define routing rules as appropriate.
As indicated before, your DNS should point to the Application Gateway: it will handle the routing to one or other App Service based on the route, /eu/* or /*, provided by the client.
The order of the routes is important: once a rule is matched, it will be the one processed.
Application Gateway is a regional service: Azure Front Door leverages a similar functionality (and much more) globally.
Please, consider review the associated costs of these services.
I am answering my own question to hopefully help others in the same situation. This was simply done using a reverse proxy. This article explains everything you need to set it up - https://ruslany.net/2014/05/using-azure-web-site-as-a-reverse-proxy/
I want to implement the below redirection in Azure AppGateway v1
https://first.demo.com/home/ => https://second.demo.com/home/
is this doable? If so, how do I do it?
A simple redirection to an external site can be achieved on Application gateway v1 but not a URL rewrite.
Reference : https://learn.microsoft.com/en-us/azure/application-gateway/redirect-overview
Application Gateway v2 and WAF v2 SKU supports the capability to add, remove, or update HTTP request and response headers, while the request and response packets move between the client and back-end pools. You can also rewrite URLs, query string parameters and host name. You can use server variables to evaluate rewrite conditions and rewrite headers.
Reference :
https://learn.microsoft.com/en-us/azure/application-gateway/rewrite-http-headers-url
https://learn.microsoft.com/en-us/azure/application-gateway/rewrite-http-headers-portal
HTTP header and URL rewrite features are only available for the Application Gateway v2 SKU. So you cannot achieve the above requirement using Application gateway v1.
Important points to consider:
In the case of a URL rewrite, Application Gateway rewrites the URL before the request is sent to the backend. This will not change what users see in the browser because the changes are hidden from the user.
In the case of a URL redirect, Application Gateway sends a redirect response to the client with the new URL. That, in turn, requires the client to resend its request to the new URL provided in the redirect. The URL that the user sees in the browser will update to the new URL.
If you wish to upgrade your Application gateway from v1 sku to v2 sku, an Azure PowerShell script is available in the PowerShell gallery to help you migrate from your v1 Application Gateway/WAF to the v2 Autoscaling SKU. This script helps you copy the configuration from your v1 gateway. Traffic migration is still your responsibility.
For more information, please refer : https://learn.microsoft.com/en-us/azure/application-gateway/migrate-v1-v2
Working on a project where we are starting to use Deployment Slots in our App Services.
All our Prod apps are located behind Application Gateway, and we would like to also have our Slots located behind Application Gateway.
I understand we can not do this using "App Services" as target type in the Backend Pools as of now, but wondered if it is doable using "IP Address or FQDN" as target type.
I have tried to set it up, with various changes in the "HTTP Settings", Probe and so, but haven´t gotten it up spinning.
Can anyone confirm if this is possible, and have any tips on how this should be configured?
Thanks!
I was able to get this working on one of my slots.
Basically setup the listener with your necessary protocol, port cert, hostname, etc... I'm using multi-site listeners so I can have multiple URLs for the one AppGW/Public IP.
The rule points to the listenter, backend pool and appropriate http setting.
The HTTP setting should be configured to connect to your app service URL accordingly. I'm using the azurewebsite.net URL, so I use well known CA cert & override hostname from backend target:
The backend pool then points to the azurewebsites.net URL:
Make sure that GET / works on your app service and returns 200-399 HTTP status codes. Anything outside that range is a failure and the backend pool will be removed. If you need to create a custom health probe to a URL that will respond properly, or adjust the acceptable HTTP status code (if 401 or 403 due to required auth, then just override it with that for testing purposes for now).
I'm trying to do it again with a second slot and running into 502 errors from the App Gateway... However, I'm also waiting on DNS changes from my network team. My first one with my company domain works via hosts file edit, but the 2nd slot (which has 2 different URLs/listeners configured in the AppGW) doesn't want to work the same way for some reason.
I'm trying to setup empty azure web app to be reverse proxy following exact same steps as described here: https://tomssl.com/2015/06/15/create-your-own-free-reverse-proxy-with-azure-web-apps/. First of all it seems that allowedservervariables can not be transformed, it is set to deny in application.config file. When i remove them i just get 404 not found when i try to access my webapp (HTTP Error 404.4 - Not Found
The resource you are looking for does not have a handler associated with it.).
Anyone have some suggestions?
Cheers
You should try Azure Function Proxies instead
https://markheath.net/post/azure-functions-v2-proxies
A developer can create an Azure Function Proxy within the same UI as a Function App. Within the configuration, a developer will be asked to provide a Route template, identify which HTTP methods are allowed and provide a Backend URL where the HTTP request will be routed to. Backend URLs do not need to be static as you can dynamically set the URL based on content within the request or from your application settings.
I'm migrating a complete infrastructure over to Azure; it's been slow going as there's so much to learn and for every two steps forward, there seems to be one step back.
After what seems like an eternity, I think I've got it all sorted with one exception.
The architecture is as follows:
Azure Traffic Manager ==> 2 Azure Application Gateways (geo separated) ==> Azure App Service
A custom domain is used for the traffic manager and the gateways are listening for the same domain and, when the route matches, passing on the requests down to the app service.
The actual app itself is a ASP.NET MVC application and it uses forms authentication; and this is where the challenge happens.
When navigating to the public address: client.domain.com and hitting the website, it determines that the user is not authenticated and sends the browser to the login page... so far so good but, rather than using client.domain.com/login it uses the web-server dns name, so client.azurewebsites.com/login
How do I go about changing the behaviour so that it uses the external DNS name rather than the website name?
I can't setup custom domains on the app service as the only route into the site is via the gateway as this is also the firewall.
Is there some Web Config setting I can make? I'm looking at the outbound rewrite rules but these seem to only work on tags rather than 302 redirects.
Any thoughts would be most welcome.
You need to setup custom dns names on your webapp (you can use TXT record to verify dns name, so i dont see a reason why you can add it to the webapp). or you can alter the code.
In order to solve this problem, I had to make a code change to the web app itself. Not ideal but it worked.
What I had to do was to extend the code that redirects an unauthenticated request to the login page by sniffing for the X-Original-Host HTTP Header that the App Gateway forwards on. This contains the public facing DNS name. If the header is present and it is on a pre-approved white-list (so as to prevent any hijacking), then redirect the user to the login page for this domain, rather than the one the server is listening on directly (so use client.domain.com rather than client.azurewebsites.com)