Serverless face-off: Azure vs AWS overview

With the explosive growth of online services, we’ve seen over 2020, it’s clear the Public Cloud is going to pervade our lives increasingly. The Internet is full of articles listing differences between platforms. But when we look closer, it all seems to fall into same groups: compute, storage, and networking. Yes, naming is different, but fundamentals are pretty much identical between all major providers.

Last time

We explored a few differences between AWS S3 and Azure Storage. On paper both Azure and AWS offers are comparable: Azure has Functions and AWS calls theirs Lambda. But subtle differences begin to show up right from the beginning…

Creating resources Azure vs AWS

Without even getting into writing any code yet we are greeted by the first difference: AWS allows to either create standalone functions or to provision Lambda Apps that are basically CloudFormation templates for a function and all related resources such as CodeCommit repo, S3 Bucket and project pipeline for CICD. Azure on the other hand always prompts to structure functions by sitting them inside a Function App. The reason for doing that is, however, slightly different: Function App is a collection of functions that share the same App Service Plan.

Serverless Invocation

AWS does not assume any triggers and we’d need to add one ourselves. Adding an API Gateway as a trigger is totally possible and allows for HTTPS setup if need be. But because trigger is external to the function – we need to pay closer attention to data contract: API reference is helpful but the default API gateway response of 500 makes it hard to troubleshoot.

Portal editor functionality

Another obvious difference between the platforms is built-in code editor experience. In AWS it is only an option for interpreted language runtimes (such as Node.js, Python and Ruby):

finding code editor in AWS portal is very easy
if runtime is not supported, you would get a blue message

Azure has its own set of supported runtimes. And of course, things like .NET and PowerShell get full support. There’s however one gotcha to keep in mind: Linux hosting plans get limited feature set:

rich experience editing code in Azure
even though .net is a first party runtime - using Linux to host it ruins the experience

.NET version support

AWS supports .NET Core 2.1 and 3.1 and conveniently provides selection controls, while Azure by default only allows for version 3.1 for newly created function apps:

AWS is an open book: picking runtime version is easy
Azure makes it a no-choice and might look very limiting, but read on...

At first look such omission is very surprising as one would expect more support from Microsoft. This however is explained in the documentation: .NET version is tied to Functions Runtime version and there is a way to downgrade all the way down to v1.x (which runs on .NET 4.7!):

it is possible to downgrade Function Runtime version. but there are limitations and gotchas


Language support.NET Core 2.1, .NET Core 3.1, Go, Java, Node.Js, Python, Ruby, PowerShell Core.NET Core 3.1, .NET Core 2.2, .NET 4.7, Node.Js, Python, Java, PowerShell Core
OSLinuxWindows or Linux (depending on runtime and plan type)
TriggersAPI Gateway, ELB, heaps moreBuilt-in HTTP/Timer, heaps more
HierarchyFunction or Function appFunction App
Portal code editor support Node.JS, Ruby, PythonNode.js, .NET, PowerShell Core,

Cloud face-off: hosting static website

With the explosive growth of online services we’ve seen over 2020, it’s pretty clear the Public Cloud is going to pervade our lives more and more. The Internet is full of articles listing differences between platforms. But when we look closer, it all seems to pretty much fall into same groups: compute, storage and networking. Yes, naming is is different, but fundamentals are pretty much identical between all major providers.

Or are they?

Today we’re going to try and compare two providers by attempting to achieve the same basic goal – hosting a static web page.

the web page is going to be extremely simple:

     <body ng-app="myApp" ng-controller="myCtrl">
     <h2>Serverless API endpoint</h2>
     <input type="text" ng-model="apiUrl" /><button ng-click="fetch(apiUrl)" >Fetch</button>
         <h2>Function output below</h2>
             {{ eventBody| json }}
         <script type="text/javascript" src="" />


With AWS, static website hosting is a feature of S3. All we need to do is create a bucket, upload our files and enable “Static website hosting” in Properties:

these warnings seems to hint at something…

One may think that this is all we have to do. But that huge information message on the page seems to be hinting at the fact that we might need to enable public access to the bucket. Let us test our theory:

indeed, there’d be no public access to our static assets by default

okay, this is fair enough – making a bucket secure by default is a good idea. One point to note here, is that enabling public access on this only bucket will not be enough. We will also need to disable “Block Public Access” on account level, which seems a bit too extreme at first. But hey, you cannot be too secure, right. AWS goes to great lengths to make it very obvious when customers do something potentially dangerous. Anyway, we’d go and enable the public access on account and bucket as instructed:

The first thing that jumps out here is a “Not Secure” warning. Indeed, S3 exposes the website via good old HTTP. And if we wanted secure transport – we’d have to opt for CloudFront.

Storage account

With Azure, the very first thing that we’d get to deal with would be the naming convention: Storage Account names can only contain lowercase letters and numbers. So right out of the gate, we’ll have to strip all dashes from our name of choice. Going through the wizard it’s relatively easy to miss the “Networking” section, but it’s exactly here we get to chose if our account will have public access or not. And by default it will be! So if you want it – you’ll have to tweak the security. Anyway, moving on to “Advanced” tab, we’re presented with another key difference: Storage Account endpoints use HTTPS by default.

Having created the account we should first enable the “Static Website hosting” option.

Reason for this order is that Azure creates a special container called $web, that we’ll then upload files to. But after we have done that – it’s pretty much done:


Both AWS and Azure allow configuring CORS for static websites. AWS is pretty upfront about it in their docs. Azure however makes a specific callout that CORS is not supported on static websites. My testing, however, indicates that it seems to work as intended. Consider the following scenario. We’d use the same website, but add a web font. And load it from across the other cloud: so Azure copy of the site will attempt to source the font from AWS and vice versa:

<link rel="stylesheet" href="css/stylesheet-aws.css" type="text/css" charset="utf-8" />
<style type="text/css">
body {
font-family: "potta_oneregular"

and the stylesheet would look like so (note the URL pointing to Azure):

@font-face {
     font-family: 'potta_oneregular';
     src: url('') format('woff2'),
          url('') format('woff');
     font-weight: normal;
     font-style: normal;

initially, this set up indeed results in a CORS error:

but the fix is very easy, just set up CORS in Azure:

and we get a fully working cross-origin resource consumption:

Doing it the other way around is a bit more complicated. Even though AWS allows us to configure policies, lack of HTTPS endpoint means browsers will likely refuse to load the fonts and we’d be forced onto CloudFront (which has its own benefits, but that would be a completely different story).


AspectAWS S3Azure Storage Account
Public by defaultnoyes
HTTPS with own domain namenoyes
Allows for human-readable namesyesnot really
CORS supportconfigurablenot supported by static websites (despite what the docs claim)