Scott Hanselman

Setting up Application Insights took 10 minutes. It created two days of work for me.

March 13, '18 Comments [15] Posted in ASP.NET | Azure | DotNetCore
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I've been upgrading my podcast site from a 10 year old WebMatrix site to modern open-source ASP.NET Core with Razor Pages. The site is now off the IIS web server and  running cross-platform in Azure.

I added Application Insights to the site in about 10 min just a few days ago. It was super easy to setup and basically automatic in Visual Studio 2017 Community. I left the defaults, installed a bit of script on the client, and enabled the server-side profiler, and AppInsights already found a few interesting things.

It took 10 minutes to set up App Insights. It took two days (and work continues) to fix what it found. I love it. This tool has already given me a deeper insight into how my code runs and how it's behaving - and I'm just scratching the service. I'll need to do some videos and/or more blog posts to dig deeper. Truly, you need to try it.

Slow performance in other countries

I could fill this blog post with dozens of awesome screenshots of the useful charts, graphs, and filters that I got by just turning on AppInsights. But the most interesting part is that I turned it on really expecting nothing. I figured I'd get some "Google Analytics"-type behavior.

Then I got this email:

Browser Time is slow in Bangladesh

Huh. I had set up the Azure CDN at to handle all the faces for each episode. I then added lazy loading so that the webite only loads the images that enter the browser's viewport. I figured I was pretty much done.

However I didn't really think about the page itself as it loads for folks from around the world - given that it's hosted on Azure in the West US.

18.4 secs to load the page in Bangladesh

Ideally I'd want the site to load in less than a second, but this is my archives page with 600 shows so it's pretty heavy.

That's some long load times

Yuck. I have a few options. I could pay and load up another copy of the site in South Asia and then do some global load balancing. However, I'm hosting this on a single small (along with a dozen other sites) so I don't want to really pay much to fix this.

I ended up signing up for a free account at CloudFlare and set up caching for my HTML. The images stay the same. served by the Azure CDN.

Lots of requests from Cloudflare

Fixing Random and regular Server 500 errors

I left the site up for a while and came back later to a warning. You can see my site availability is just 93%. Note that there's "2 Servers?" That's because one is my local machine! Very cool that AppInsights also (optionally) tracks your local development server as well.

1 Alert!

When I dig in I see a VERY interesting sawtooth pattern.

Pro Tip - Recognizing that a Sawtooth Pattern is a Bad Thing (tm) is an important DevOps thing. Why is this happening regularly? Is it exactly regularly (like every 4 hours on a schedule?) or somewhat regularly (like a garbage collection issue?)

What do these operations have in common? Look closely.


It's not a GET it's a HEAD. Remember that HTTP Verbs are more than GET, POST, PUT, DELETE. There's also HEAD. It literally is a HEADer call. Like a GET, but no body.

HTTP HEAD - The HEAD method is identical to GET except that the server MUST NOT return a message-body in the response.

I installed HTTPie - which is like curl or wget for humans - and issue a HEAD command from my local machine while under the debugger.

C:>http --verify=no HEAD https://localhost:5001
HTTP/1.1 500 Internal Server Error
Content-Type: text/html; charset=utf-8
Date: Tue, 13 Mar 2018 03:41:51 GMT
Server: Kestrel

Ok that is bad. See the 500? I check out AppInsights and see it has the full call stack. See it's getting a NullReferenceException as it tries to Render() the Razor page?

Null Reference Exception

It turns out since I'm using Razor Pages, I have implemented "OnGet" where I do my data base work then pass a model to the pages to generate HTML. However, if someone issues a HEAD, then the pages still run but the local data work never happened (I have no OnHead() call). I have a few options here. I could handle HEAD myself. I could no-op it, but that'd be a lie.

THOUGHT: I think this behavior is sub-optimal. While GET and POST are distinct and it makes sense to require an OnGet() and OnPost(), I think that HEAD is special. It's basically a GET with a "don't return the body" flag set. So why not have Razor Pages automatically delegate OnHead to OnGet, unless there's an explicit OnHead() declared? I'll file an issue on GitHub because I don't like this behavior and I find it counter-intuitive. I could also register a global IPageFilter to make this work for all my site's pages.

The simplest thing to do is just to delegate the OnHead to to the OnGet handler.

public Task OnHeadAsync(int? id, string path) => OnGetAsync(id, path);

Then double check and test it with HTTPie:

C:\>http --verify=no HEAD https://localhost:5001
HTTP/1.1 200 OK
Content-Type: text/html; charset=utf-8
Date: Tue, 13 Mar 2018 03:53:55 GMT
Request-Context: appId=cid-v1:e310025f-88e9-4133-bc15-e775513c67ac
Server: Kestrel

Bonus - Application Map

Since I have AppInsights enabled on both the client and the server, I can see this cool live Application Map. I'll check again in a few days to see if I have fewer errors. You can see where my Podcast Site calls into the backend data service at Simplecast.

An application map that shows all the components, both client and server

I saw a few failures in my call to SimpleCast's API as I was failing to consistently set my API key. Everything in this map can be drilled down into.

Bonus - Web Performance Testing

I figured while I was in the Azure Portal I would also take advantage of the free performance testing. I did a simulated aggressive 250 users beating on the site. Average response time is 1.22 seconds and I was doing over 600 req/second.

38097 successful calls

I am learning a ton of stuff. I have more things to fix, more improvements to make, and more insights to dig into. I LOVE that it's creating all this work for me because it's giving me a better application/website!

You can get a free Azure account at or check out Azure for Startups and get a bunch of free Azure time. AppInsights works with Node, Docker, Java, ASP.NET, ASP.NET Core, and other platforms. It even supports telemetry in Electron or Windows Apps.

Sponsor: Get the latest JetBrains Rider for debugging third-party .NET code, Smart Step Into, more debugger improvements, C# Interactive, new project wizard, and formatting code in columns.

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Upgrading my podcast site to ASP.NET Core 2.1 in Azure plus some Best Practices

March 10, '18 Comments [5] Posted in Azure | DotNetCore
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I am continuing to upgrade to podcast's site. Today I upgraded it to .NET Core 2.1, keeping the work going from my upgrade from "Web Matrix WebPages" from last week. I upgraded to actually running ASP.NET Core 2.1's preview in Azure by following this blog post.

Pro Tip: Be aware, you can still get up to 10x faster local builds but still keep your site's runtime as 2.0 to lower risk. So there's little reason to not download the .NET Core 2.1 Preview and test your build speeds.

At this point the podcast site is live in Azure at Now that I've moved off of the (very old) site I've quickly set up some best practices in just a few hours. I should have taken the time to upgrade this site - and its "devops" a long time ago.

Here's a few things I was able to get done just this evening while the boys' did homework. Each of these tasks were between 5 and 15 min. So not a big investment, but they represented real value I'd been wanting to add to the site.

Git Deploy for Production

The podcast site's code now lives in GitHub and deployment to production is a git push to master.

Deploying from GitHub

A "deployment slot" for staging

Some people like to have the master branch be Production, then they make a branch called Staging for a secondary staging site. Since Azure App Services (WebSites) has "deployment slots" I choose to do it differently. I deploy to Production from GitHub, sure, but I prefer to push manually to staging rather than litter my commits (and clean them up or squash commits later - it's just my preference) with little stuff.

I hooked up Git Deployment but the git repro is in Azure and just for deploy. Then "git remote add azure ..." so when I want to deploy to staging it's:

git push staging

I use it for testing, so ya, it could have been test/dev, etc, but you get the idea. Plus the Deployment Slot/Staging Site is free as it's on the same Azure App Service Plan.

A more sophisticated - but just as easy - plan would be to push to staging, get it perfect then do a "hot swap" with a single button click.

Deployment Slots can have their own independent settings if you click "Slot Setting." Here I've set that this ASPNETCORE_ENVIRONMENT is "Staging" while the main one is "Production."

Staging Slots in Azure

The ASP.NET Core runtime picks up that environment variable and I can conditionally run code based on Environment. I run as "Development" on my local machine. For example:

if (env.IsDevelopment()){

Don't let Google Index the Staging Site - No Robots

You should be careful to not let Google/Bing/DuckDuckGo index your staging site if it's public. Since I have an environment set on my slot, I can just add this Meta Robots element to the site's main layout. Note also that I use minified CSS when I'm not in Development.

<environment include="Development">
    <link rel="stylesheet" href="~/css/site.css" />
<environment exclude="Development">
    <link rel="stylesheet" href="~/css/site.min.css" />
<environment include="Staging">
    <meta name="robots" content="noindex, follow">

Require SSL

Making the whole ASP.NET Core site use SSL has been on my list as well. I added my SSL Certs in the Azure Portal that added RequreHttps in my Startup.cs pretty easily.

I could have also added it to the existing IISRewriteUrls.xml legacy file, but this was easier and faster.

var options = new RewriteOptions().AddRedirectToHttps();

Here's how I'd do via IIS Rewrite Middleware, FYI:

<rule name="HTTP to HTTPS redirect" stopProcessing="true">
    <match url="(.*)" />
       <add input="{HTTPS}" pattern="off" ignoreCase="true" />
    <action type="Redirect" url="https://{HTTP_HOST}/{R:1}"
redirectType="Permanent" />

Application Insights for ASP.NET Core

Next post I'll talk about Application Insights. I was able to set it up both client- and server-side and get a TON of info in about 15 minutes.

Application Insights

How are you?

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About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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az webapp new - Azure CLI extension to create and deploy a .NET Core or nodejs site in one command

February 22, '18 Comments [3] Posted in Azure
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az webapp newThe Azure CLI 2.0 (Command line interface) is a clean little command line tool to query the Azure back-end APIs (which are JSON). It's easy to install and cross-platform:

Once you got it installed, go "az login" and get authenticated. Also note that the most important switch (IMHO) is --output:

usage: az [-h] [--output {json,tsv,table,jsonc}] [--verbose] [--debug]

You can get json, tables (for humans), or tsv (tab separated values) for your awks and seds, and json (or the more condensed json-c).

A nice first command after "az login" is "az configure" which will walk you through a bunch of questions interactively to set up defaults.

Then I can "az noun verb" like "az webapp list" or "az vm list" and see things like this:

128→ C:\Users\scott> az webapp list
Name Location State ResourceGroup DefaultHostName
------------------------ ---------------- ------- -------------------------- ------------------------------------------
Hanselminutes North Central US Running Default-Web-NorthCentralUS
HanselmanBandData North Central US Running Default-Web-NorthCentralUS
myEchoHub-WestEurope West Europe Running Default-Web-WestEurope
myEchoHub-SouthEastAsia Southeast Asia Stopped Default-Web-SoutheastAsia

The Azure CLI supports extensions (plugins) that you can easily add, and the Azure CLI team is experimenting with a few ideas that they are implementing as extensions. "az webapp new" is one of them so I thought I'd take a look. All of this is open source and on GitHub at and is discussed in the GitHub issues for azure-cli-extensions.

You can install the webapp extension with:

az extension add --name webapp

The new command "new" (I'm not sure about that name...maybe deploy? or createAndDeploy?) is basically:

az webapp new --name [app name] --location [optional Azure region name] --dryrun

Now, from a directory, I can make a little node/express app or a little .NET Core app (with "dotnet new razor" and "dotnet build") then it'll make a resource group, web app, and zip up the current folder and just deploy it. The idea being to "JUST DO IT."

128→ C:\Users\scott\desktop\somewebapp> az webapp new  --name somewebappforme
Resource group 'appsvc_rg_Windows_CentralUS' already exists.
App service plan 'appsvc_asp_Windows_CentralUS' already exists.
App 'somewebappforme' already exists
Updating app settings to enable build after deployment
Creating zip with contents of dir C:\Users\scott\desktop\somewebapp ...
Deploying and building contents to app.This operation can take some time to finish...
All done. {
"location": "Central US",
"name": "somewebappforme",
"os": "Windows",
"resourcegroup": "appsvc_rg_Windows_CentralUS ",
"serverfarm": "appsvc_asp_Windows_CentralUS",
"sku": "FREE",
"src_path": "C:\\Users\\scott\\desktop\\somewebapp ",
"version_detected": "2.0",
"version_to_create": "dotnetcore|2.0"

I'd even like it to make up a name so I could maybe "az webapp up" or even just "az up." For now it'll make a Free site by default, so you can try it without worrying about paying. If you want to upgrade or change it, upgrade either with the az command or in the Azure portal. Also the site ends at up <name>!

DO NOTE that these extensions are living things, so you can update after installing with

az extension update --name webapp

like I just did!

Again, it's super beta/alpha, but it's an interesting experiment. Go discuss on their GitHub issues.

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About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Exploring the Azure IoT Arduino Cloud DevKit

January 8, '18 Comments [0] Posted in Azure | Hardware
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Someone gave me an Azure IoT DevKit, and it was lovely timing as I'm continuing to learn about IoT. As you may know, I've done a number of Arduino and Raspberry Pi projects, and plugged them into various and sundry clouds, including AWS, Azure, as well as higher-level hobbyist systems like AdaFruit IO (which is super fun, BTW. Love them.)

The Azure IoT DevKit is brilliant for a number of reasons, but one of the coolest things is that you don't need a physical one...they have an online simulator! Which is very Inception. You can try out the simulator at You can literally edit your .ino Arduino files in the browser, connect them to your Azure account, and then deploy them to a virtual DevKit (seen on the right). All the code and how-tos are on GitHub as well.

When you hit Deploy it'll create a Free Azure IoT Hub. Be aware that if you already have a free one you may want to delete it (as you can only have a certain number) or change the template as appropriate. When you're done playing, just delete the entire Resource Group and everything within it will go away.

The Azure IoT DevKit in the browser is amazing

Right off the bat you'll have the code to connect to Azure, get tweets from Twitter, and display them on the tiny screen! (Did I mention there's a tiny screen?) You can also "shake" the virtual IoT kit, and exercise the various sensors. It wouldn't be IoT if it didn't have sensors!

It's a tiny Arduino device with a screen!

This is just the simulator, but it's exactly like the real MXChip IoT DevKit. (Get one here) They are less than US$50 and include WiFi, Humidity & Temperature, Gyroscope & Accelerometer, Air Pressure, Magnetometer, Microphone, and IrDA, which is ton for a small dev board. It's also got a tiny 128x64 OLED color screen! Finally, the board also can go into AP mode which lets you easily put it online in minutes.

I love these well-designed elegant little devices. It also shows up as an attached disk and it's easy to upgrade the firmware.

Temp and Humidity on the Azure IoT DevKit

You can then dev against the real device with free VS Code if you like. You'll need:

  • Node.js and Yarn: Runtime for the setup script and automated tasks.
  • Azure CLI 2.0 MSI - Cross-platform command-line experience for managing Azure resources. The MSI contains dependent Python and pip.
  • Visual Studio Code (VS Code): Lightweight code editor for DevKit development.
  • Visual Studio Code extension for Arduino: Extension that enables Arduino development in Visual Studio Code.
  • Arduino IDE: The extension for Arduino relies on this tool.
  • DevKit Board Package: Tool chains, libraries, and projects for the DevKit
  • ST-Link Utility: Essential tools and drivers.

But this Zip file sets it all up for you on Windows, and head over here for Homebrew/Mac instructions and more details.

I was very impressed with the Arduino extension for VS Code. No disrespect to the Arduino IDE but you'll likely outgrow it quickly. This free add on to VS Code gives you intellisense and integration Arduino Debugging.

Once you have the basics done, you can graduate to the larger list of projects at that include lots of cool stuff to try out like a cloud based Translator, Door Monitor, and Air Traffic Control Simulator.

All in all, I was super impressed with the polish of it all. There's a LOT to learn, to be clear, but this was a very enjoyable weekend of play.

Sponsor: Get the latest JetBrains Rider for debugging third-party .NET code, Smart Step Into, more debugger improvements, C# Interactive, new project wizard, and formatting code in columns.

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Setting up a managed container cluster with AKS and Kubernetes in the Azure Cloud running .NET Core in minutes

December 14, '17 Comments [11] Posted in Azure
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After building a Raspberry Pi Kubernetes Cluster, I wanted to see how quickly I could get up to speed on Kubernetes in Azure.

  • I installed the Azure CLI (Command Line Interface) in a few minutes - works on Windows, Mac or Linux.
    • I also remembered that I don't really need to install anything locally. I could just use the Azure Cloud Shell directly from within VS Code. I'd get a bash shell, Azure CLI, and automatically logged in without doing anything manual.
    • Anyway, while needlessly installing the Azure CLI locally, I read up on the Azure Container Service (AKS) here. There's walkthrough for creating an AKS Cluster here. You can actually run through the whole tutorial in the browser with an in-browser shell.
  • After logging in with "az login" I made a new resource group to hold everything with "az group create -l centralus -n aks-hanselman." It's in the centralus and it's named aks-hanselman.
  • Then I created a managed container service like this:
    C:\Users\scott\Source>az aks create -g aks-hanselman -n hanselkube --generate-ssh-keys
    / Running ...
  • This runs for a few minutes while creating, then when it's done, I can get ahold of the credentials I need with
    C:\Users\scott\Source>az aks get-credentials --resource-group aks-hanselman --name hanselkube
    Merged "hanselkube" as current context in C:\Users\scott\.kube\config
  • I can install Kubenetes CLI "kubectl" easily with "az aks install-cli"
    Then list out the nodes that are ready to go!
    C:\Users\scott\Source>kubectl get nodes
    NAME                       STATUS    ROLES     AGE       VERSION
    aks-nodepool1-13823488-0   Ready     agent     1m        v1.7.7
    aks-nodepool1-13823488-1   Ready     agent     1m        v1.7.7
    aks-nodepool1-13823488-2   Ready     agent     1m        v1.7.7

A year ago, Glenn Condron and I made a silly web app while recording a Microsoft Virtual Academy. We use it for demos and to show how even old (now over a year) containers can still be easily and reliably deployed. It's up at

I'll deploy it to my new Kubernetes Cluster up in Azure by making this yaml file:

apiVersion: apps/v1beta1
kind: Deployment
name: fancypants
replicas: 1
app: fancypants
- name: fancypants
image: glennc/fancypants:latest
- containerPort: 80
apiVersion: v1
kind: Service
name: fancypants
type: LoadBalancer
- port: 80
app: fancypants

I saved it as fancypants.yml, then run kubectl create -f fancypants.yml.

I can run kubectl proxy and then hit http://localhost:8001/api/v1/namespaces/kube-system/services/http:kubernetes-dashboard:/proxy/#!/overview?namespace=default to look at the Kubernetes Dashboard, proxyed locally, but all running in Azure.


When fancypants is created and deployed, then I can find out its external IP with:

C:\Users\scott\Sources>kubectl get service
fancypants LoadBalancer 80:31040/TCP 7m
kubernetes ClusterIP <none> 443/TCP 18m

There's my IP, I hit it and boom, I've got fancypants in the managed cloud. I only have to pay for the VMs I'm using, and not for the VM that manages Kubernetes. That means the "kube-system" namespace is free, I pay for other namespaces like my "default" one.


Best part? When I'm done, I can just delete the resource group and take it all away. Per minute billing.

C:\Users\scott\Sources>az group delete -n aks-hanselman --yes

Super fun and just took about 30 min to install, read about, try it out, write this blog post, then delete. Try it yourself!

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About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Disclaimer: The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.