Scott Hanselman

How to set up ASP.NET Core 2.2 Health Checks with BeatPulse's AspNetCore.Diagnostics.HealthChecks

December 12, '18 Comments [4] Posted in ASP.NET | DotNetCore | Open Source
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Availability TestsASP.NET Core 2.2 is out and released and upgrading my podcast site was very easy. Once I had it updated I wanted to take advantage of some of the new features.

For example, I have used a number of "health check" services like elmah.io, pingdom.com, or Azure's Availability Tests. I have tests that ping my website from all over the world and alert me if the site is down or unavailable.

I've wanted to make my Health Endpoint Monitoring more formal. You likely have a service that does an occasional GET request to a page and looks at the HTML, or maybe just looks for an HTTP 200 Response. For the longest time most site availability tests are just basic pings. Recently folks have been formalizing their health checks.

You can make these tests more robust by actually having the health check endpoint check deeper and then return something meaningful. That could be as simple as "Healthy" or "Unhealthy" or it could be a whole JSON payload that tells you what's working and what's not. It's up to you!

image

Is your database up? Maybe it's up but in read-only mode? Are your dependent services up? If one is down, can you recover? For example, I use some 3rd party back-end services that might be down. If one is down I could used cached data but my site is less than "Healthy," and I'd like to know. Is my disk full? Is my CPU hot? You get the idea.

You also need to distinguish between a "liveness" test and a "readiness" test. Liveness failures mean the site is down, dead, and needs fixing. Readiness tests mean it's there but perhaps isn't ready to serve traffic. Waking up, or busy, for example.

If you just want your app to report it's liveness, just use the most basic ASP.NET Core 2.2 health check in your Startup.cs. It'll take you minutes to setup.

// Startup.cs
public void ConfigureServices(IServiceCollection services)
{
services.AddHealthChecks(); // Registers health check services
}

public void Configure(IApplicationBuilder app)
{
app.UseHealthChecks("/healthcheck");
}

Now you can add a content check in your Azure or Pingdom, or tell Docker or Kubenetes if you're alive or not. Docker has a HEALTHCHECK directive for example:

# Dockerfile
...
HEALTHCHECK CMD curl --fail http://localhost:5000/healthcheck || exit

If you're using Kubernetes you could hook up the Healthcheck to a K8s "readinessProbe" to help it make decisions about your app at scale.

Now, since determining "health" is up to you, you can go as deep as you'd like! The BeatPulse open source project has integrated with the ASP.NET Core Health Check API and set up a repository at https://github.com/Xabaril/AspNetCore.Diagnostics.HealthChecks that you should absolutely check out!

Using these add on methods you can check the health of everything - SQL Server, PostgreSQL, Redis, ElasticSearch, any URI, and on and on. Just add the package you need and then add the extension you want.

You don't usually want your health checks to be heavy but as I said, you could take the results of the "HealthReport" list and dump it out as JSON. If this is too much code going on (anonymous types, all on one line, etc) then just break it up. Hat tip to Dejan.

app.UseHealthChecks("/hc",
new HealthCheckOptions {
ResponseWriter = async (context, report) =>
{
var result = JsonConvert.SerializeObject(
new {
status = report.Status.ToString(),
errors = report.Entries.Select(e => new { key = e.Key, value = Enum.GetName(typeof(HealthStatus), e.Value.Status) })
});
context.Response.ContentType = MediaTypeNames.Application.Json;
await context.Response.WriteAsync(result);
}
});

At this point my endpoint doesn't just say "Healthy," it looks like this nice JSON response.

{
status: "Healthy",
errors: [ ]
}

I could add a Url check for my back end API. If it's down (or in this case, unauthorized) I'll get this a nice explanation. I can decide if this means my site is unhealthy or degraded.  I'm also pushing the results into Application Insights which I can then query on and make charts against.

services.AddHealthChecks()
.AddApplicationInsightsPublisher()
.AddUrlGroup(new Uri("https://api.simplecast.com/v1/podcasts.json"),"Simplecast API",HealthStatus.Degraded)
.AddUrlGroup(new Uri("https://rss.simplecast.com/podcasts/4669/rss"), "Simplecast RSS", HealthStatus.Degraded);

Here is the response, cool, eh?

{
status: "Degraded",
errors: [
{
key: "Simplecast API",
value: "Degraded"
},
{
key: "Simplecast RSS",
value: "Healthy"
}
]
}

This JSON is custom, but perhaps I could use the a built in writer for a free reasonable default and then hook up a free default UI?

app.UseHealthChecks("/hc", new HealthCheckOptions()
{
Predicate = _ => true,
ResponseWriter = UIResponseWriter.WriteHealthCheckUIResponse
});

app.UseHealthChecksUI(setup => { setup.ApiPath = "/hc"; setup.UiPath = "/healthcheckui";);

Then I can hit /healthcheckui and it'll call the API endpoint and I get a nice little bootstrappy client-side front end for my health check. A mini dashboard if you will. I'll be using Application Insights and the API endpoint but it's nice to know this is also an option!

If I had a database I could check one or more of those for health well. The possibilities are endless and up to you.

public void ConfigureServices(IServiceCollection services)
{
services.AddHealthChecks()
.AddSqlServer(
connectionString: Configuration["Data:ConnectionStrings:Sql"],
healthQuery: "SELECT 1;",
name: "sql",
failureStatus: HealthStatus.Degraded,
tags: new string[] { "db", "sql", "sqlserver" });
}

It's super flexible. You can even set up ASP.NET Core Health Checks to have a webhook that sends a Slack or Teams message that lets the team know the health of the site.

Check it out. It'll take less than an hour or so to set up the basics of ASP.NET Core 2.2 Health Checks.


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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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How to remove words from the Windows Autocorrect Spell Check Dictionary

December 7, '18 Comments [4] Posted in Win10
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Well crap. I was typing really fast and got a squiggly, so I right-clicked on it and rather than selecting the correct word from the autocorrect dictionary, I clicked Add To Dictionary.

I added the MISSPELLED WORD to the Dictionary! Now Windows is suggesting that I spell this word (and others) wrong in all apps.

At this point I also realized that I had no idea how to REMOVE a word from the Windows Spell Check Dictionary. However, I do know that Windows isn't a black box so there must be a dictionary somewhere. It's gotta be a file or a registry key or something, right?

It's even easier than I thought it would be. The Windows 10 custom dictionaries are at %AppData%\Microsoft\Spelling\

The Windows 10 custom dictionaries are at %AppData%\Microsoft\Spelling\

I just opened the default.dic file in Notepad and removed the misspelled word.

Opening default.dic in Notepad

Whew. I can't tell you how many wrong words have found there way in there over the years. Hope this helps you in some small way.


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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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Announcing WPF, WinForms, and WinUI are going Open Source

December 4, '18 Comments [34] Posted in Open Source | Windows Client | WPF
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Buckle up friends! Microsoft is open sourcing WPF, Windows Forms (winforms), and WinUI, so the three major Windows UX technologies are going open source! All this is happening on the same day as .NET Core 3.0 Preview 1 is announced. Madness! ;)

.NET Core 3 is a major update which adds support for building Windows desktop applications using Windows Presentation Foundation (WPF), Windows Forms, and Entity Framework 6 (EF6). Note that .NET Core 3 continues to be open source and runs on Windows, Linux, Mac, in containers, and in the cloud. In the case of WPF/WinForms/etc you'll be able to create apps for Windows that include (if you like) their own copy of .NET Core for a clean side-by-side install and even faster apps at run time. The Windows UI XAML Library (WinUI) is also being open sourced AND you can use these controls in any Windows UI framework.

That means your (or my!) WPF/WinForms/WinUI apps can all use the same controls if you like, using XAML Islands. I could take the now 10 year old BabySmash WPF app and add support for pens, improved touch, or whatever makes me happy!

WPF and Windows Forms projects are run under the .NET Foundation which also announced changes today and the community will guide foundation operations. The .NET Foundation is also changing its governance model by increasing the number of board members to 7, with just 1 appointed by Microsoft. The other board members will be voted on by the community! Anyone who has contributed to a .NET Foundation project can run, similar to how the Gnome Foundation works! Learn more about the .NET Foundation here.

On the runtime and versioning side, here's a really important point from the .NET blog that's worth emphasizing IMHO:

Know that if you have existing .NET Framework apps that there is not pressure to port them to .NET Core. We will be adding features to .NET Framework 4.8 to support new desktop scenarios. While we do recommend that new desktop apps should consider targeting .NET Core, the .NET Framework will keep the high compatibility bar and will provide support for your apps for a very long time to come.

I think of it this way. If you’ve got an existing app that you’re happy with, there is no reason to port this to .NET Core. Microsoft will support the .NET Framework for a very long time, given that it’s a part of Windows. But post .NET Framework 4.8. new features will usually only become available in .NET Core because Microsoft is drastically reducing the risk and thus rate of change for .NET Framework. So if you’re building a new app or you’re actively evolving an existing app you should really start looking at .NET Core. Porting to .NET Core certainly isn’t free, but it offers many benefits, such as better performance, XCOPY deployment for the framework itself, and feature set that is growing fast, thanks to open source. Choose the strategy that makes sense for your project and/or business.

I don't want to hear any of this "this is dead, only use that" nonsense. We just open sourced WinForms and have already taken Pull Requests. WinForms has been updated for 4k+ displays! WPF is open source, y'all! Think about the .NET Standard and how you can run standard libraries on .NET Framework, .NET Core, and Mono - or any ".NET" that's out there. Mono is enabling running .NET Standard libraries via WebAssembly. To be clear - your browser is now .NET Standard capable! There are open source projects like https://platform.uno/ and Avalonia and Ooui taking .NET in new and interesting places. Blazor makes Web UIs in .NET with (preview/experimental) client support with Web Assembly and server support included in .NET 3.0 with Razor Components. Only good things are coming, my friends!

.NET ALL THE THINGS

.NET Core runs on Raspberry Pi and ARM processors! .NET Core supports serial ports, IoT devices, and there's even a System.Device.GPIO (General Purpose I/O) package! Go explore https://github.com/dotnet/iot to really get your head around how much cool stuff is happening in the .NET space.

I want to encourage you to go check out Matt Warren's extremely well-researched post "Open Source .NET - 4 years later" to get a real visceral sense of how far we've come as a community. You'll be amazed!

Now, go play!

Enjoy.


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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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On Developer Advocacy

November 30, '18 Comments [4] Posted in Musings
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TeamworkNaming things is hard. I've talked before about the term "evangelism" and my dislike for it. Evangelism, Advocacy, Developer Relations, PR, Marketing, and on and on. More and more I'm just trying to educate and maybe entertain a little. So I like Edutainment, myself, hat tip to KRS-One.

I'm getting on a plane tomorrow to go to the Microsoft Azure + AI Conference @DevIntersection and the Free Microsoft Connect 2018 Event (you can watch online all day!) and as I was packing I was struck with a few thoughts I wanted to share here.

What a privilege it is to speak about products that so many people have worked on and (hopefully) so many people will enjoy. Especially ones as large as Azure or Visual Studio - thousands of people work so hard! Engineers, Program Managers, Testers, Community Members...people from all over working on each release so a select few of us get on stage to share it with you! And who am I to have this privilege?

Don't think for a second that when you're giving a technical talk that it's about you. You're sitting on a stack of software you had a small part in writing and standing on the shoulders of giants of generations of engineers and creators who came before you. When I do talks where I'm representing a huge group I reflect on this with gratitude.

If you work on any of the products I'm showing, know this; I may be one of the talking heads or a visible grand marshal but we work for you and we never forget it. My job at events like this is to make the product - your work - shine. I take that job very seriously, and if it looks like it's effortless, that's because of the massive amount of work we put into the presentation. Hours of practice, story arcs, literally blocking movement as if it were a play or stage show, camera work, and transitions. Deeping understanding what we're presenting and why it's awesome and why you're proud of it.

I'm writing this note for all the other advocates and visible community members.

What a joy and privilege it is to stand up and represent our co-workers and follow engineers and to tell the stories of the things they build!

Let that privilege both put motivation in you and propel you forward to present their work - your teams' work.

I appreciate you all, both inside and out, and I'll will do my best to represent your team and the larger community to the best of my ability.


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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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The 2018 Christmas List of Best STEM Toys for Kids

November 28, '18 Comments [11] Posted in Reviews
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Hey friends! This is my FIFTH year doing a list of Great STEM Christmas Toys for Kids! Can you believe it? In case you missed them, here's the previous years' lists! Be aware I use Amazon referral links so I get a little kickback (and you support this blog!) when you use these links. I'll be using the pocket money to...wait for it...buy STEM toys for kids! So thanks in advance!

OK, let's do it!

littleBits

I've always liked littleBits but when they first came out I thought they were expensive and didn't include enough stuff. Fast forward and littleBits have dropped in price and built a whole ecosystem of littleBits that work together. This year the most fun is the littleBits Marvel Avengers Inventor Kit. At the time of this writing, this kit is 33% off at Amazon. You can built your own Iron Man (or Ironheart!) gauntlet and load it up with littleBits that can do whatever you'd like. One particularly cool thing included is an LED Matrix that you can address directly by writing code with the iOS or Android app.

littleBits Marvel Avengers Inventor Kit

Kano - Computer Kit and Wand

Both my kids love the Kano Computer Kit, now updated for 2018. It's a complete Raspberry Pi 3 kit that includes the keyboard, mouse, case, LED lights, and everything you'd need to build a Pi. This year they've branched out to the Kano Happy Potter Coding Kit that you can use to build a wand and learn to code. The "wand" is a custom PCB with codeable LEDs, buttons, and batteries that the kids put inside a wand. The wand is Bluetooth and includes lots of tech like an accelerometer, gyroscope, magnetometer, and a vibrating rumble pack. All of this tech is controllable with laptops or smart devices and code with JavaScript.

Harry Potter Kano Coding Kit and Wand

UbTech JIMU Robot - Unicornbot Kit

UbTech has a whole series of Technics-style Robot kits. There's the usual tanks and cars, but there's also some more creative and "out there" ones like this 400-piece Unicorn Robot. It includes color sensors, server motors, a DC motor, and a light up horn. It's also codeable/controllable via an iOS or Android app. Very cool!

I'd really like their Lynx Alexa controllable walking robot but it's way out of my price range. Still fun to check out though!

Unicornbot

Erector by Meccano Kits

We've found these Erector by Meccano Kits to be inexpensive and well-built. The 25-in-1 kit is great and includes a container and over 600 pieces. I like these metal kits because they feel like the ones I had in my childhood. Kids learn how to use motors, pulleys, and other explore functional motion.

Erector Set

NatGeo's Space Atlas and the 2019 Nat Geo Almanac

Both of these great books from National Geographic are spending a lot of time in my kids' hands. The National Geographic Almanac 2019 is amazing every year. It's an annual with facts, photos, and infographics that have my kids saying "did you know?" on long car drives constantly. That's a good thing.

We are also enjoying the hardcover Space Atlas with maps of the whole solar system. 350+ pages of space, charts, maps, photos, it's both deep for adults and accessible for kids. I recommend both of these books and have them on my coffee table now.

image

Osmo Genius Kit for iPad

The Osmo Genius is quite clever and based on one deceptively simple idea - what if the iPad camera faced downward and could see the table in front of the child? It came with a base and a reflector that directs the front-facing camera downwards. Then the educational games are written to see what's happening on the table and provide near-instant feedback. You can start with the base kit and later optionally add kits and games.

Osmo Genius Kit for iPad

Elenco 130-in-1 Electronic Playground and Learning Center

I like classic toys and while toys with bluetooth and fancy features are cool, I want to balance it out with the classics that let you explore the physical world. These also tend to be more affordable as well.

I really like this classic electronic trainer with 130 experiments like an AM broadcast station, Electronic Organ, LED strobe light, Timer, Logic Circuits and much, much more. The 50-in-One version is just $16! Frankly all the Elenco products are fantastic.

image

Piper Computer Kit (2018 Edition)

I had this on the list last year but my kids still love it. We have the 2016 kit and it's been updated for 2018.

The Piper is a little spendy at first glance, but it's EXTREMELY complete and very thoughtfully created. Sure, you can just get a Raspberry Pi and hack on it - but the Piper is not just a Pi. It's a complete kit where your little one builds their own wooden "laptop" box (more of a luggable), and then starting with just a single button, builds up the computer. The Minecraft content isn't just vanilla Microsoft. It's custom episodic content! Custom voice overs, episodes, and challenges.

What's genius about Piper, though, is how the software world interacts with the hardware. For example, at one point you're looking for treasure on a Minecraft beach. The Piper suggests you need a treasure detector, so you learn about wiring and LEDs and wire up a treasure detector LED while it's running. Then you run your Minecraft person around while the LED blinks faster to detect treasure. It's absolute genius. Definitely a favorite in our house for the 8-12 year old set.

Piper Raspberry Pi Kit

I hope you have a great holiday season!

FYI: These Amazon links are referral links. When you use them I get a tiny percentage. It adds up to taco money for me and the kids! I appreciate you - and you appreciate me-  when you use these links to buy stuff.


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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.