Worker Services in .NET Core 3.0 - The New Way to Create Services

one of the new project types in dotnet core 300 is the worker service in this video we're gonna be looking at what that project type is why we should use it and how he did install it and get it running our a specific example today will be a tool to monitor a website to ensure that it's up and running so we can see exactly how the service operates the source code for today's video is available to download using the link below in the description you'll also find links there to sign up for my mailing list and for my patreon page as you watch this video please post your thoughts and questions in the comments below I will do my best to respond to you now if you haven't come across me before my name is Tim Corey ends my goal to make learning c-sharp easier one of the ways I do that is by teaching context there are a lot of tutorials out there that teach you what to do I got a few steps beyond that to show you when to do it why you should do it or why you shouldn't do it what the pitfalls are to avoid and what the best practices are basically I get you Rea for the real world if that's the type of training you're interested in subscribe to my channel and hit the little bell icon to be notified when I release new videos okay let's get started in Visual Studio so I have Visual Studio 2019 if we scroll down here we got create a new project and we're gonna select the worker process so to do that we can go under here and select service so worker service or we could just search for out of the table just type worker service now in this case I'm using a c-sharp worker service so make sure you have that notice it will install on Linux Mac and Windows alright when you give this worker service a name so let's call it the website status and we'll call it website status app and we create this it will create our workers service which we have a only really one option here and that is to enable docker support if we like it we can do that later if we saw you want that but for right now we're going to leave docker support off so when we have one option here as the worker serve as the empty project now no I am using the preview 8 version of.net core 3 as of the recording of this video dotnet core 3 has not been released but preview 8 is the the go live preview and so this we the same even if you have the the full go live version of.net core 3 so you get create and this is going to create our worker service for us and there's not much to see when we start this but left before get into the code itself let's talk through what are we doing here why do we have ass worker service what's this project type all about the idea behind a worker service is it's a background service something that runs in the background that just keeps running basically forever and on your Windows PC you may notice that you have Windows services that's what a worker service could be is a Windows service and those just run a background even if you're not logged in and so you have applications that are running even when no one's logged out of the computer as long as the computers running those services are running and that's what a service is on Linux it would be a daemon and those run in the background continually we can even run these in Azure but for today's demo what we're going to do is create a service that will install on Windows and run in the background continually to my to our website to make sure that it's up so let's look at what a worker service is composed of this is a dotnet core project so we have our app settings JSON which has our logging information in it if you see my logging video you know what those settings are and then we have the program C gasps file which is very very basic right now just a couple of settings and then we have the worker file which this is where all the quote-unquote real work gets done think of this as the true user interface of your service now some people have asked the question well how do I get a real user interface on my service something I can see and the answer is you don't you shouldn't that's not a service at that point is just an application so we're not gonna see any output however when it comes to testing that's always been the problem we created services in the dotnet framework we had this issue where a service by the dotnet framework for definition had to be installed and orderly run and therefore is very hard a test and so we came up with other ideas I did a video on top shelf which is a a tool that takes console applications and allows me to run as services easily if you can do that even without the top shelf but that allow us to run console application visually and then we're ready to deploy it we just deployed it and it now we're in a background all the time this does something similar to that in that we can hit the Run button right now and it will run and it will execute and we can see it in a console when we install it we won't see that console it won't pop up but is doing an exact same thing so let's look at what this service is doing right out of the box you know just no configuration what's it doing from the bear template well we have the constructor that's asking for an ilogger and that's again just the logging information that's we cover that in a previous video so that's just set up the logger this is the only real section of work that's new compared to other projects and that is execute async this is an override so it's it's coming from the background service class execute async it's overriding that and saying okay here's what you do when the execute async is called and it says while not stopping token dot is cancellation requested so it's passing us stop a stopping token and so an asynchronous programming that currently for in my a sink a wait video actually I think it's may advanced async that I covered this we have the idea we can pass in a cancellation token to an asynchronous event to say hey I know I kicked you off and I'm waiting for you be done but I actually want you to stop now instead of later and so that's that stopping token and so this while loop is gonna keep going over and over and over again until silom passes in the cancellation token and that cancellation token is someone stopping the service otherwise it'll keep running forever and that's what a service does it just runs now inside this while loop we log that the worker is running and the time it's running and then we await one second and again we pass in that stop token in case we were we're stopping halfway through that delay so all this does is it continually runs and writes out a log entry and then it waits one second and that writes out a log entry and then it waits one second continually until something happens to stop this execution and that stop all is kind of you know it's not visible here but that stop happens whenever you stop the service let's see this in action let's run this just as it is and we get that the worker is started when it was started and I get the worker run message and now if I hit enter he's if you click on the screen it pauses the output so by hitting Enter it it now should need alive messages and notice every second we're getting a new message from our logger so that's what the service does if I hit control-c to stop this it says application is shutting down and then it it's ready to close the application so that's actually a closed message which currently isn't visible in our application that's because it's there's a a override to see that but if we look at the background service there's a start a sinking a stop a sink stop async calls that message that says hey I'm stopping now and that's what logged out the stop start is where we start up and it doing start up tasks that we need to so now let's go back here and make this our own we're gonna take us over and do something instead of the basic boilerplate stuff which is pretty easy understand it's just it runs this method and the way we kind of pause it between iterations is this task dot delay which is asynchronous so that returns back that it returns control if we needed to to something else but in this case it's nothing return control to so I'm gonna take out this message right here we don't need that right now and I'll leave the ones let's change this one second to five seconds if you don't want to check every second for the website being up that actually would put some strain on our website if we're always requesting the main page over and over and over again so ideally officially more like a minute and we can do what I've seen done which is I think is a good pattern either you say 60 times 1000 1000 being seconds there for 60 would be 60 second 60 seconds or one minute and so that kind of indicates hey that's that's one minute or the time instead of saying 60,000 where it might be a little harder to understand building I do is to change these into constants but we won't go there all right so that would be one minutes with the time but for this demonstration I don't want to go like I want to do five seconds because we need hassling visual and I don't want to wait a full minute between iterations alright so every five seconds is fine the every five sites what I do is we're going to load our web page using the HTTP client but if you knowing about HTTP client you're supposed to open one client for the application not once every time you make a call otherwise what could happen is you can actually clog up your connections and crash your computer so let's not do that let's open up the HTTP client once HTTP client controlled dot to add the using statement for system net dot HTTP and we'll call this client now I'm not going to Nishal eyes it here I'm just going to create the private variable to use I want to initialize it when the service starts to do that I have a a public override and here's my options one of the options is start async now I will call the the base start async because I'll make sure that the I do whatever the base was doing just in case but then I'm going to before that do client equals new HTTP client that way it starts when the service starts now we have the client initialized we can call it down here so we can say var result equals a wait client dot get async and then they a call to our website and our website is HTTP s/w I am Tim Cory calm there we go that's going to load my website it's gonna wait for it to load so if this takes if this load takes five seconds it's going to wait for that before we go forward so in theory if this takes five seconds it's the only another five seconds that's good because otherwise what happened is we might go to step on each other's toes we're still waiting waiting one and then we wait five seconds and then call it again and we're step on each other's toes waiting for this because if it's down it may have a delay of up to thirty seconds to let us know that so now we had our website if we say result dot we have our content we have our headers we have the is success status code and we have the status code itself so with that we can do is we can have an if statement if result dot is success status code then logger dot log information the website was up is up it's means simple like that we can even have a status code status code status code like so and then the status code be result dot status code that way the message has the actual status code just in case it wasn't a to hot abejas it was another you know to something because anything that to hundreds is success but may is more information we can glean out of what our code was now the else statement here this is what happens if the site is down well I could say logger.log we could say log critical or log exception and I want to be very clear on us let's do log log error and say the website is down status code status code so this would say the website is down however this is not how you report that the the site is down this is just logging what happened that's it this is not what you use to report that the website is down instead what you want to do here is before this you'd want to have some call to the database to say you know report to the website is down or fire off an email to somebody to say hey your website is down or send a text message something like that that is what that's the actual action that would come out of this service now I'm not going to take it to that extent today because this is not intended to be a complete application I don't want to spend time on things that aren't really focused on the service itself but logging is not logging just for informational purposes it's not a way to then communicate problems necessarily okay so kind of differentiate those two things there you probably do more than just log this error you'd want to perform some action but for this where it's gonna perform an action and in fact I am NOT gonna take my website down therefore you probably even see this error code okay so now we've done the action of actually logging either success or failure and we're done and now we're going to wait five seconds and do it all over again great so that's the entire service that's all we have to do the one thing I want to add I'm going to add up here public override I might override these stop async and say client dot dispose so client httpclient has a dispose method I want to call that when you stop the service basically are being a good citizen here and making sure that we're taking care of our connections we want to leave that HTTP client open as long as the service stays open but when the service shuts down we should properly shut down the client as well so that will run the dispose when the stop is called so now we have a service that when it starts up starts up the HTTP client when it stops it stops the HTTP client and in between every five seconds it's going to check our website to see if it is up and if it is that logs that and if it's not it logs the error indicating so let's run this and see what happens there we go the website is up the status code is okay the website is up and the status code is ok and if we wait five more seconds they'll pop up again hey we're still good so website is still up and running if I hit ctrl C that's going to close down the client properly and shut down our service which at this point is running just a console application all right so our applications working but now you want to install it as a service if you're familiar windows services here's a list of my services that are installed you'll see is this long list of things that run on your computer so for example the xbox live game save which actually comes with Windows 10 that right now is a manual triggered start for the service whereas workstation is running and it's an automatic start these are all services that run the background Windows Update and so on what we're gonna do is create our own and we called it website let's look for website here there is no website here there's web account manager web management web client and then Wi-Fi we're gonna create ours and called it website status that's our service name so the first step to do that is we need to think through how we get these messages right now we get them on the console as well as we get them in the output window but that's not going to help us when it comes to a service because a service isn't going to expose the console it's not going to have the debug window so how are we going to see what these messages are well in this case what I do is I want to install a tool called Sarah log and Sarah log is going to help me because it will allow me to log to a text file so the first thing I do is right-click any dependencies and manage NuGet packages and we're going to install two packages one is Sarah log dot asp net core that sounds a little weird that says asp net core that's asp net core but that's actually what we use for dotnet core projects it hasn't caught up to the fact that there's more project types and just asp net projects there's other dotnet core product types as well so ASP not core that's fine I'm installing it I am installing the preview version just because I'm using pre-release dotnet core 3 but you shouldn't have to check this box for pre-release the other thing that install is Sarah log syncs dot file this is a pretty simple one and what this is is it allows us to write to a text file again really simple logging just to a text file so I can see some sort of output as it comes through okay I now have those two installed the only other thing you do for configuring Sarah log is to go to program CS now you to add a few things in here the first one is I say using Sarah log and then down here in my I cut this out well you know what let's just we're gonna put it below and we'll put it back in resi log da logger equals new logger configuration now this is the way that the documentation for Sarah log says you should plug it started using it we can move this into our app settings JSON but I didn't want to cover Sarah log too in this video and sorry I do just the basics of what they recommend for getting started so the dot minimum level is a debug and then the minimum level dot override remember that we can override different levels we're gonna override Microsoft and say that the the log event level he is going to be they don't come in information but I am going to say warning so let's let's be a little more you know not listen to as much and let's make this into a using statement here so control dot to add the user statement and then after this we're gonna say enrich from log context and then write to file as what's call a sink that's the the way they identify how where to send the logs to it's right to a file in this case I'm gonna say C colon slash temp slash worker service and let's call this file log file dot txt and then dot create logger alright so that's the set up that sets up Sarah law that's configuration now that's why it says configuration it configures it and gets it already so we can inject that and basically override the default logger that's built into asp net core or dotnet core now we have this we can actually log the start of our application so let's do a try and we'll catch any exceptions just in case we have a problem starting our application and at the end of this we will return so if we have a problem with our application we're gonna log it whereas a log dot fatal notice this is log L og not underscore logger that's because we're using the the static class for serial logger to begin with because we have not yet injected it so long dot fatal that says here's the exception and there was a problem starting the service something like that and we're going to try here whereas a log dot information starting of the service and then we'll make our call this call right here like so and afterwards after a dumb making that call will return since we're done we should actually exit the application either way we have a finally here and that finals going to run with a catch or where they go through the Tri without catching either way log dot close and flush in what this does is it ensures that if there's any messages in a buffer that they get written before we close out the application so what can happen is longers have to be efficient in order be efficient one of the ways they do that is they batch things they don't necessarily always write the log exactly when you'd call it instead they may wait for a little bit and then write any in a batch in a group and so if you're halfway through that batching process and you close the application either intentionally by showing it down or unintentionally crashing it either way you don't want to lose those last messages therefore we're going to do is we're going to call the close and flush which ensures that those messages get written out wherever they're going so that's the the big modification force area log and the final one is after the semicolon we can hit dot and configure oops not configure it's use use Sarah log that's it now it's yelling me here because it wants to not have the lambda expression here let's just redo that I prefer this this way so we have this returns thing that returns a default builder which remember that default builders sets up the debug and the console as two different log sources as well as the event source is a third and so we've already got that configured in the default builder but use Sarah log says that nope not actually instead throw that stuff out we're gonna use our stuff instead which that's the configuration right here so that's what happens when do they use Sarah log so we're already set up for Sarah we can make sure this is true by running this and I'm gonna move over that folder and we'll move over the window as well and notice it's already a log file dot txt in this and there's nothing going on in my console now my console I'll hit ctrl C and it close the application if I open up this text file it says starting up a service and then the website is up the status code is okay twice so the application is working as expected and it's now writing to a text file instead of our console now we could add another sync for console and then have both going if you wanted to but we're not going to do that because we just want to see on the text file because it will be installed as a service for debugging purposes may we add the console back in but I think we're good now there is one more thing to do before we're a to make this into a Windows service now remember this is called worker service not Windows service and that's because a worker service can run on Windows as a window service it can run on Linux as a demon or it can run in Azure they can also run Mac I'm not quite sure if it runs as a daemon as well there or something else I'm not terribly familiar with Mac haven't been for a few years now so with that we can't call it a Windows service because it's a worker service it can do service work wherever it is so how do you make sure that it will work as a Windows service with some Windows specific things well we need to install a new get packaged the eyebrows and we search for Microsoft Dodds extensions dot hosting dot windows services that's plural we get this install right here then this will allow us to configure it as a Windows service we hit install we accept and once we're done I'll show you the not so big configuration change here in my create host builder inside program CS I say use Windows service and we're done we've now configured this to run as a Windows service now we can deploy it so how do you deploy a service well we're gonna do it the the manual way if you have as your DevOps this is where you can create a process do it automatically for you which is is better but for development purposes we can just right click on our project and say publish and it says do you want to get an add your web job well no actually I don't instead I'll publish it to a folder well what folder you want publish it to let's use this same folder where our log file is so I'll copy that and I will paste it here I'm going to create that profile now if you notice it says it's kind of cut off here but uses the release configuration so it's release not debug even if we have debug right here it's released for dotnet core app 3.0 its framework dependent meaning that it depends on dotnet core being installed on a machine the target runtime is portable or we could dial it in to one particular runtime and the location where it's going to be installed or at least deployed to is this right here okay save and publish and if you watch this folder here once the publish exceeds there we go we've got a whole bunch of files in here including website status Exe and websites TAS DLL this is the release version of our application meaning this is production-ready notice it also has a DLL specific to Sarah log and Sarah log dotnet core and some of the extensions do we install so it has all the stuff specific to our application all the the nougat packages we installed all those dll's are have been brought in now we have this website stash Exe how do we actually get this to run in our services you don't have this service listed here we could run the exe but that's just going to run it as a console app so this is where we have to register this service so I'm gonna bring over a PowerShell now I've run PowerShell if you notice the upper left-hand corner as administrator you need admin access to run this and we're gonna use a command called sc4 not set content but service control major tool now there is in PowerShell as as powershell specific there is a shortcut called SC which is set content so you cannot you'll see examples where I say just do SC and then they have the command you can't do that in PowerShell you can do that in the command line non powershell for powershell you have to say SC exe which indicates that's not the shortcut for SC set content but instead the executable for the service Control Manager tool so SC exe we're going to create a service and let's call it website status that's the name of our service and then we have a bin path and that is what I've been path equals and this is the location where our exe is located and it's located at notes press space after that is required all I've got to work with alpha space but the documentation says it's required to have a space after the equal not before after so C colon slash temp slash worker service slash website status dot exe I don't have to put quotes around this unless there's spaces in any of the paths now I do want to set the start equal to auto meaning it will automatically start when Windows does and that's it this will run as a local service and it will start automatically when Windows to us if I hit enter it says service has been created successfully if we come back over here and refresh will now see website status are it's a little small let's see if we can't zoom in here a little bit so there we go so website status is automatic but notice does not say running by default when you install something it does not start so I started just right click and say start notice it runs as a local system permissions so start and now it's running if we come back to our our worker services and look at that log file DX or LOC all that txt if we open this up notice that it started the service a second time and we've got three okay's in there we close it out and open it back up we now have five okay's so this is running a background it will continue to run as long as Windows does or until something catastrophic were to happen and that is how we install our service and you may wonder well that's great but how do you uninstall your service between we want to put a new version in there let's move this off a screen first thing to do is stop your service always stop your service before you do anything else that does that graceful shutdown and then calls that stop asynchronous method they will make sure our web or HTTP client has been closed successfully now we have this done we can run new command on PowerShell and that new command is SC exe delete website status and that's the same name we gave it up here this is whatever name you want to be the exe is where we have to specify the exe that actually is but this is the name e1 want to give the service itself don't put spaces there you can give a display name which is an additional parameter here and the display name can be something more friendly with spaces in it so SC exe delete website status and alia is successfully notice a success here if it appears like it's waiting if it's set if it does not give you the success but instead says it's been communicate or something like that to say that it's trying then what happens there's a couple different possibilities one is sometimes this window right here if it's open it will cause this service to not be able to close or delete and so we'll wait for that and so you just close this window and it will allow it to find delete the other thing is if you didn't stop your service first that can cause it to not be able to delete so make sure you go in there and stop your service first and then come back and it will be deleted so just make sure you check those things if you have an error when you go to delete your service now that it's stopped if we look at the log file notice we have all these right here so it's been running we didn't put a message in saying that we're stopping successfully we should probably do that but we now have statuses for all these saying that yes we're capturing that it is running and we know that's we don't know it's it stopped successfully but we should put a log message in there to say that so let's do this let's control a and delete everything in here we'll do all over again but this time put a message in there saying that I've stopped successfully so it's kind of our worker dot CS and right here we should have a log message it's a logger dot log information that says these service has been stopped so like that and I think that's good we could put it over here where we say after this we could put stopping the service or something like that but I think putting it right in the stop async after you dispose that way we know that yes it's been disposed of properly so with that we can run this to test it see right course has no display with ctrl C to stop it if we come over here to our log file dot txt and sure enough we didn't get even get a chance to run that once before we stopped the service and it does record that's been stopped so let's delete that file and we say you know what yes I want to push that to production so we right click and say publish we already have the profile so we just hit publish again and once that's done we get our files we come back over to PowerShell we push up twice to create the same command that SC exe create it's been successful if we come up here and we refresh our list it's there and it stopped we hit start it's now been started if we go back to our our file which is right here look at log file a service has started and it's called the the lookup three times it's all been and now if we come back over here let's just indicate or let's just show you that that message if you try and stop it the wrong way so let's delete this and says of course it does sometimes a wheel sometimes it won't it says it's deleted let's see if it actually is by refreshing this and it says running but disabled which is odd right if we go a log file there is no stopping here we have one two three four five six seven eight nine oak case now they come back here and look again one two three four five six seven eight nine ten eleven okay so it's still running even though I said to delete the service so what's going on if we control a and hit delete it's going even that error it says hey you can't do that because it's currently in use so what's going on to come back here and we say delete it again it says delete failed the specified service has been marked for deletion so if we restart windows it will delete the service but since it's still running it's not deleting our service well if you come over here and we say stop and now notice it's gone you don't have to refresh hey just go on if we try to delete again it says does not exist and if we come back over here and say delete we could delete our files but first illicit log file and notice the service has been stopped so it got stopped properly this time now we can delete all of our files and start over again with a new version so that's what the worker service is all about really simple stuff to get started it's just as execute async and if you need to do something with a start or stop you can override those and open them up if you want to have some type of messaging or logging coming out of this just to indicate how the service is running then you probably need to create a new logger like I did with its era log where I use that to write to a text file so you can write to a text file you can write as JSON to a text file you can write to the console is a whole lot of different options especially with sera log where you can use but in general that's all you do for a service you'll probably end up calling out to other libraries can bring in class libraries here and do more work and maybe if you're going to do more work you expand out this delay and say maybe you don't do it every five seconds maybe do it every minute or something like that now this is not for jobs where you want to schedule them necessarily there are tools out there to allow you to do scheduling specifically for example there's a hangfire delighted it with with.net code and that's more for scheduling this is more for long-running processes things that are continually being running you might want to a service do things like check a database table to see if any new entries have been entered in or maybe even get triggered by a database table when new entries come in or you might minor a queue to see if a new king of the queue and if it does you do something with it these are the kind of things that a service is great at just that continual running a background waiting for something to happen and when it does it immediately jumps in and starts doing work how long you wait between looking is up to you definitely don't drop it down so solo and some so fast that you're going to cause load on your own system this is not a load test you don't want to be every millisecond but if it makes sense to do it every second that's fine it makes sense to wait every minute that's fine as well I encourage you to try and find that sweet spot between responsiveness where it happens automatically and quickly but the same time not so fast that it's causing performance problems on your system okay so that is a worker service love to hear your thoughts love to hear what you plan using a worker service for if you do and thanks for watching as always I am Tim quarry [Music] you

Channel: IAmTimCorey

Views: 219,003

Keywords: .net core 3.0 worker service, .net core 3, .net core tutorial, .net core 3.0, tim corey, iamtimcorey, worker service, windows service, c# windows service, c# windows service tutorial, c# worker service, dependency injection c#, ilogger c#, ilogger c# .net core, serilog, serilog .net core

Id: PzrTiz_NRKA

Length: 47min 8sec (2828 seconds)

Published: Mon Sep 09 2019

Reddit Comments

[u/PhatBoyG]

The main reason Topshelf isn’t going to see further development for .NET Core, because it isn’t needed.

And I’m happy about it!

[u/FireflyDarked]

Good job.

[u/Korzag]

Glad to see they've finally got a replacement for the classic Windows service project for .Net 4.8 or less. I was developing a project at my last job that used background services and couldn't really use .Net Core for this reason alone.

[u/PublicSealedClass]

Can't be arsed with videos, but here's an article I Googled about these, they're pretty cool:

https://wakeupandcode.com/worker-service-in-asp-net-core/

[u/Anon_Logic]

I've already followed this video on YouTube.

Only issue I had was when trying to add the NuGet WindowsService (I did have it typed out) it wouldn't find it. Had it verbatum in the search and it refused. Had to use the package manager console to install it. Other than that, fantstic video

[u/duckwizzle]

Whaaat this is awesome! I've been writing a bunch of applications like this but have been using my own template. Will be awesome to have an out of the box solution

[u/jesus_h_jones]

I saw this in my YouTube subs. I have written a few .Net Core 2.x console application worker type services this year, I wish this project type had been baked earlier... I love your videos, keep it up!

[u/princeMartell]

We have a service that runs on various different industrial equipment control computers. Currently we have to support all the way back to windows XP. Is there any hope for replacing that with .NET core? ( My assumption is no... But I can always dream...)

[u/HashtagAllergy]

Tim, I just wanted to say thank you for your great videos. I‘m following you since about a year now and have always enjoyed watching your quality content to dive into concepts I wasn‘t familiar with before (e.g. async programming). There‘s something about your way of structuring these videos and/or your calm voice that just lets all the knowledge flow directly into my brain.

Oh, and I also accidentally discovered that just listening to the audio makes me fall asleep really quickly. Tried to listen to one on the couch, which led to an impromptu power nap. 5/5 would nap to C# again.

Keep up the great work!