With built-in load balancing for cloud services and virtual machines, we can create highly-available and scalable applications in minutes. But what is Azure Application level routing and load balancing service and how it differs from built-in load balancing for cloud services and virtual machines
I assume you are talking about Azure Application Gateway and Azure Load Balancer.
The primary difference is that AG works at Layer 7, while LB works at Layer 4.
AG can be used for HTTP traffic routing, TLS termination, HTTP traffic filtering etc.
So you can for example, route requests to the /images path to a different App Service than the rest of the requests.
LB only understands TCP and UDP, and routes packets based on rules to one of the machines in a back-end pool.
So for example when a TCP packet arrives on port 80, LB can route it to a random virtual machine in a collection of VMs serving a web app.
What is Azure Application Gateway?
Load balancer documentation
Related
I have having a hard time find a solution for this.
I have an Azure Internal Load Balancer (level 4). And I have ONLY one Virtual Machine act as the backend pool for the said Load Balancer.
And fun part starts here, I have multiple Docker containers running on that Virtual Machine. Running Nginx Web servers on ports 8080 and 8081.
And now I want to balance the load between these two ports. Literally what I want is something like below in the photo:
So according to the photo, the request comes from abc.xyz.com and it should hit the Load Balancer, and then it should route the traffic to the only VM running multiple docker containers in multiple ports.
How can I achieve this behavior?
I have already setup A frontend configuration with private ip, a rule, backend pool
As per this article(https://learn.microsoft.com/en-us/azure/container-instances/container-instances-virtual-network-concepts#unsupported-networking-scenarios), placing an Azure Load Balancer in front of container instances in a networked container group is not supported and similarly it is not possible to route the traffic on containers to their specific ports running on a single Virtual Machine. The above solution works on VM level not on container level.
The only workaround for this scenario would be to use Azure Application gateway as Microservice architecture is supported on App gateway. To probe on different ports, you need to configure multiple HTTP settings. Reference:
https://learn.microsoft.com/en-us/azure/application-gateway/application-gateway-faq#can-one-backend-pool-serve-many-applications-on-different-ports
Azure Application Gateway is a web traffic load balancer that enables you to manage traffic to your web applications. And you can create an internal application gateway. To do that you can create an Application Gateway with both public and private frontend IP address and 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.
Reference: https://learn.microsoft.com/en-us/azure/application-gateway/configuration-front-end-ip ,
https://learn.microsoft.com/en-us/azure/application-gateway/application-gateway-faq#how-do-i-use-application-gateway-v2-with-only-private-frontend-ip-address
In my application, I needed IPv6 support for WAF. Since IPv6 yet not supported by the WAF can I use a load balancer connected to the WAF as the following diagram (because of IPv6 supports Load Balancer)? Is this a good design?
You can not use the Azure load balancer to connect to an application gateway since Azure load balancer only works with VM, VMS, or availability sets as its backend. Have a look at backend pool endpoints here.
More info: Overview of IPv6 for Azure Load Balancer
I have a use case where my cluster has 3 VMs working as head node in HPC Pack and a bunch of other VMs working as compute nodes.
So basically, after creating this cluster, i must install a special HCP client, from this client, i type the DNS name of each of VMs to access the HPC management interface.
For example: https://head-node-1.azure.com
Of course, if i access this DNS from Chrome, i only see IIS page.
I wants to create a load balancer with its DNS name. Let's say https://load-balancer.azure.com
So from my client, every time i access load balancer DNS name, i can see the management interface, not IIS page.
How can i do that?
Not sure I'm understanding you correctly. Basically, Azure Application Gateway supports URL path-based routing rules.
Actually, Application Gateway supports web-based traffic load balancing. [Azure load balancer][2] supports stream-based traffic. If you want to listen to the protocol HTTP or HTTPS, you can use Application Gateway. Per your description, you could not access HPC management interface from web explorer, you could use a 4 layer load balancing based on TCP/UDP.
So you could create a public-facing load balancing and add the head node VMs as the backend pools. Create a health probe and load balancing rules to specify the ports you want to listen for your HPC management interface on the each of VMs.
Hope this helps, let me know if you have any concerns.
I've got multiple questions on the setup of a gateway and VM, so here is what I have actually.
I've got an Application Gateway, and two VM Ubuntu, everything hosted on Azure. They are all on the same Virtual Network. Both VM have only a private IP (10.1.0.4 and 10.1.0.5) and the Gateway have a private IP (10.1.1.4) and a public IP. Because only the Gateway have a public IP, I guess that everything have to go through it, and this is what I want to.
The goals I try to achieve :
Make a load balancer on the port 1680, redirected to port 1680.
To redirect the SSH of each VM to connect specifically to one because at the moment, they have no public IP. Is it possible to do this with a path based rule ? Like www.example.com/VM1 to connect by SSH to the first VM ? If no, what can be used to differentiate the SSH connection of the VM1 and of the VM2 ?
To redirect the port 80 of the gateway to the port 8080 of a specific VM. As my previous example, www.example.com/adminPanelVM1 to connect to the first VM on port 80 (redirected to port 8080 on the VM)
I already managed to create the redirection of the port 1680 of the Gateway with an HTTP Parameter, a Listener and a Rule.
Azure Application Gateway
The Azure Application Gateway operates at the layer 7 in the OSI model on the HTTP/HTTPS/WebSocket protocols, because of that any other protocol (like SSH), is not possible to route.
You got a few options tho.
You can use a Network Security Group, or NSG, for access control to your virtual machines. In the NSG you define where the traffic can come from that is allowed access to the VMs.
A NSG behaves like a access-control-list filtering traffic based on source and destination information and evaluating rules in order of priority. See this page for more information about NSGs.
Another option is to use a load balancer.
Azure Load Balancer
If you need to do port mapping, like you describe in your question, then a simple load balancer might be a better solution for you. An Azure Load Balancer works at a lower level in the in the OSI model, namely layer 4 (transport layer), handling TCP/UDP traffic.
So, if you are using a load balancer, then you can set up NAT rules to forward your traffic to specific machines, in other words, if you want to do:
LB port 1234 redirects to VM1 port 22 and
LB port 4312 redirects to VM2 port 22
you can do that using PowerShell as described in the Creating a public load balancer in Resource Manager by using PowerShell article.
There are quite a few steps but it walks you through the whole process of creating NAT rules, NICs and associated virtual machines.
Azure Application Gateway vs Azure Load Balancer?
These two cervices are distinctly different services and are trying to solve different problem, although those problems might look similar :)
The primary uses of an Application Gateway are:
SSL termination
cookie-based session affinity
round robin for load balancing traffic
Where as the Azure Load Balancer service works as the TCP/UDP level and support e.g. port mapping.
Cost wise, the load balancer service is free while the application gateway is billed per hour.
There are many great articles on this topic, when to pick which service. See for example the links for more details
When to use Azure Load Balancer or Application Gateway
Frequently asked questions for Application Gateway
We have a third party product run as a windows service, expose as a web service. The goal is to dynamically provision the service instances in business peak hours.
Just to run the thought with you guys,
- I've already deployed the service on multiple vm, configured the vm in the same cloud service Availability Sets, configured azure to turn on/off vm instances based on cpu use
- I am to configure a separate vm, run iss arr there, add points to the endpoints on the vm configured above, with the hope ARR balanced the requests to the back-end vm dynamically
Will this work? What's the best practice for the IaaS scale? Any thoughts? Truly appreciate the input.
If I have understood correctly, you just need to use the built in load balancer of the cloud service. Create a load balance set for your endpoint. For example, if you want to balace the incoming traffic to port 80 in your application all you have to do is to create a LB-set for this port and configure this set to all the VMs in the Cloud Service.
The Azure Load Balancer randomly distributes a specific type of
incoming traffic across multiple virtual machines or services in a
configuration known as a load-balanced set. For example, you can
spread the load of web request traffic across multiple web servers or
web roles.
Configure a load-balanced set
Azure load balancing for virtual machines
No matter if VMs are up or down, once it turns on and if the endpoint is configured in the same LB-set, it will automatically start responding to requests once port 80 is online (IIS started and is returning STATUS 200 OK, for example). So, answering your question: yes, it will work with auto-scale or manuallying turning on/off vms.