Azure : What do I put in front of my (web) application?

Introduction

In almost every design session, the following question pops up…

“What do I put in front of my web application to secure it?”

Today we will take a look at the different options at hand. Or better said … What is the difference between the following services?

Azure CDN vs Azure Front Door versus Azure Application Gateway (WAF) vs Azure Traffic Manager

 

TL;DR

If you do not want to go through the entire post, here is a brief summary of the different options ;

My gut feeling tells me this will already help out like a lot! 😉

 

Web Application Firewall (WAF) : Azure Front Door vs Azure Application Gateway

Both Azure Front Door and Azure Application Gateway state that they can be configured to act as a Web Application Firewall. They key difference here is that the Azure Application Gateway can do a “detection only”-mode and that it supports CRS 2.2.9, 3.0, and 3.1. This means that there are out-of-the-box rules that provide a baseline security against most of the top-10 vulnerabilities that Open Web Application Security Project (OWASP) identifies. With Azure Front Door, you need to configure the rules yourself to your liking.

In terms of networking, there also is a very important difference between both. An Azure Application Gateway can be deployed (injected) in(to) an Azure VNET (Virtual Network). By doing so, the traffic between this gateway and your internal backend will flow through a private network. With Azure Front Door, your backend is always based on a public endpoint. Though you can harden / lock down the connectivity between Azure Front Door and your application by restricting the ingress of the traffic.

 

Geographic Redundancy : Azure Front Door vs Azure Traffic Manager

If you want to publish your webapp across regions, then you can leverage Azure Front Door or Azure Traffic Manager to do so. The most important thing to know is that Azure Traffic Manager is DNS based and serves as a redirection mechanism. Azure Front Door will serve as an entrypoint (think reverse proxy). So when using Traffic Manager, you will typically look at another reverse proxy / WAF (like Azure Application Gateway) to cover the need for the secure entrypoint for your application. Next to that, the Azure Traffic Manager is more feature rich in terms of the routing mechanisms, though Azure Front Door (just like Azure Application Gateway) have the advantage of working at layer 7 (Reference : OSI Model), thus also do header/path based routing.

 

Caching Content : Azure CDN vs Azure FrontDoor

The first thing to realize is what the intent was of both solutions?

  • Azure CDN is a Content Delivery Network and was designed to delivery content. Think in terms of media files (“video”) for instance.
  • Azure Front Door was built as a scalable entry point for applications (like Office 365)

Both will do caching (check the links above), though they differ in the sweet spots. Azure Front Door will cache files up to 8MB (as a side trait), where you should think that this is mainly done to optimize the delivery of your “web app”. Azure CDN its core function is caching… It was built to ensure that your files would be distributed world wide and delivered from a local pop.

The funky thing here, is that (if you ignore the Verizon and Akamai flavors of Azure CDN) both Azure CDN and Azure Front Door share the same POPs! Though the caching mechanics of both work differently.

 

DDOS

All services will have DDOS protection (“Basic”), as this is native to any Azure service! It is a key component of the Microsoft backbone actually. Though you can augment the services that reside in your VNET with the “Standard” protection. That being said, do know that the Azure Application Gateway does not scale as dynamic as the other services mentioned here (Azure Front Door and Azure Traffic Manager). So this could become a bottleneck for your design.

 

Closing Thoughts

With more than 100 services in Azure, you are bound to have services that overlap in terms of capabilities. I do hope this post provides you with some guidance towards a the external facing endpoints of your application! The above things are the recurring patterns I see in discussions with the organizations I talk to when deploying web applications on Azure.

Opinion – Cloud Native, Cloud Native and Cloud Native? What I like about, and my two cents on, running Containers, Kubernetes and/or Serverless

Introduction

In the beginning of the month I posted about my experience of moving VMchooser from “Serverless” to “Containers”. As in, moving from one way of implementing a CloudNative architecture to another… Since then, I have actually moved back to “Serverless”.  Though the cogwheels in my head have been turning 24/7 on how to put everything around this into perspective. Yesterday Yves made a tweet (reply) that really made something click inside of my head…

In today’s post I’m going to try to do a “brain dump” of several thoughts that have been floating around in my mind. Where I hope this will help you in your journey of “finding your perfect rock”. Here I will indicate what I like about the various options and what my typical advice would be to organizations looking to do a given option.

Continue reading “Opinion – Cloud Native, Cloud Native and Cloud Native? What I like about, and my two cents on, running Containers, Kubernetes and/or Serverless”

Improving your code quality by linking Azure DevOps with SonarCloud

Introduction

In a customer workshop earlier this week, Hans mentioned a very nice tool (SonarCloud). He used it “in his previous life and was very enthusiastic about it. So this immediately triggered my curiosity… 😉 As it is free for public projects, I investigated how easy it was to integrate into my existing pipelines. Which turned out to be quite easy! After browsing around a bit on how to integrate it into a YAML pipeline, I can proudly say that VMchooser is now fully hooked up with SonarCloud.

However, it did confirm my suspicion, that I am a lousy developer! 😉 Though better lousy code fulfilling a purpose than having no alternative at all?!?

Anyhow, today’s post is about the experience of moving existing pipelines to SonarCloud and investigate the results you get out of it.

Continue reading “Improving your code quality by linking Azure DevOps with SonarCloud”

Azure DevOps : Operational validation with Approval Gates & Azure Monitor Alerts

Introduction

After having migrated VMchooser from a fully Serverless infrastructure to Containers, I am currently doing the opposite move. As I can start off the same code base to basically run different deployment options in Azure. Where I found that the serverless deployment added more value for me compared to a lower cost profile. That being said, one of the big learnings I had this week is that while having an automated landscape with Terraform, some changes are rather intrusive… Where I should have checked the output of the terraform plan stage, I failed to do so. Which resulted in downtime for VMchooser. So I  was looking for way to do operational validation in the least intrusive and re-usable way. This led me to a solution where the Azure DevOps pipelines would leverage the health-check used in the Traffic manager deployment. This was already part of the deployment of course and in this a key aspect of understanding if the deployment was healthy or not.

 

Gates

In order to add validation steps in our deployment process, we can leverage the concept of Gates in Azure DevOps ;

Gates allow automatic collection of health signals from external services, and then promote the release when all the signals are successful at the same time or stop the deployment on timeout. Typically, gates are used in connection with incident management, problem management, change management, monitoring, and external approval systems.

As most of the health parameters vary over time, regularly changing their status from healthy to unhealthy and back to healthy. To account for such variations, all the gates are periodically re-evaluated until all of them are successful at the same time. The release execution and deployment does not proceed if all gates do not succeed in the same interval and before the configured timeout. The following diagram illustrates the flow of gate evaluation where, after the initial stabilization delay period and three sampling intervals, the deployment is approved.

Continue reading “Azure DevOps : Operational validation with Approval Gates & Azure Monitor Alerts”

Cloud Native Options – Personal experience when moving from Serverless to Containers

Introduction

Over the last months I have migrated VMchooser from a purely serverless implementation towards a container based one. The main reason for me to do this, was (like always) the learning effect that comes with such a refactoring. This post will run you through the various aspects that I encountered and hopefully give you a better understanding between both implementation options of a CloudNative architecture. I will divert a bit from the pure “X vs Y” comparison and also touch topics that typically come with the business discussions when thinking about both in terms of a strategic approach.

 

CloudNative?

First of all… In terms of semantics, there are some definitions floating around. When you look at the CNCF, then it seems to solely revolve around containers. Though when you look at Azure, the definition broadens up a bit… In reality, it depends a lot on the context of the person/organization you are speaking too. So do not be surprised if for some organizations the scope of CloudNative is “limited” to containers. Where for others this might be about leveraging the PaaS cloud services in a “Serverless” manner.

 

It kinda makes me think about the following “cartoon” (Source ; Simon Wardley) from a few years ago ;

Anyhow, be aware that there are different views on the semantics of “Cloud Native” and be crisp on your own when making conscious decisions.

 

Strategic Design Principle ; Portability

The design principle of software portability is high on the radar with about every organization I talk to. Here I always highlight two dimensions to take into consideration ;

Continue reading “Cloud Native Options – Personal experience when moving from Serverless to Containers”