Azure Function Apps Tutorial | Introduction for serverless programming

hey there this is Adam again and today we're going to be talking about serverless because it's probably one of the best concepts about the cloud. Managing the code without managing the servers or the infrastructure and everything at scale well what's not like it. Today we're gonna get introduction into Azure function apps.

Probably one of my favorite services, so stay tuned. So let's start with functions. Functions is a service for running small pieces of code so you have that script in dotnet or maybe java or any other languages that is supported and this is the place to go and they call those small pieces of code functions.

This is a great service and very cheap service, very scalable service for running serverless, because you don't have to manage infrastructure underneath what is important is that this service is extension of Azure App Service, so if you want to know all about features that this service has because this is an extension of the App Service I highly recommend you to watch the video on the App Service which will be linked down in the comments. So why would you use Function Apps well they have a lot of features like multiple languages, they support C# in both DotNet and DotNet Core frameworks, Java, JavaScript Typescript which is transpiled to JavaScript you have PowerShell Core, you have F# and Python, so a lot of languages that you can use and other that are popular recent days, you can use here, but additionally you can pay per use so the price is super super cheap because first four hundred thousand gigabytes of memory is free as well as first million executions are also free, so you probably will use functions in most cases without paying a dime. So I would say that's a great price, but if you extend and you go further beyond that the price is still very small because million executions cost 169 cents.

Additionally you have your own dependencies that you can bring either using NPM or NuGet you also have integrated security this is coming from the App Service. You have this integration with Azure Active Directory or any other external provider. You have simplified integration because you can combine this with external tools.

You have flexible development, because you can develop in the portal on maybe Visual Studio code or any other tool in that matter. But also you have integration of GitHub, Azure DevOps and other external repositories and this is again one of the key features that came from this being an extension to the App Service and lastly we have this as an open-source because entire SDK for functions is open-source so you can find it on a GitHub. So we were talking about this simplified integration I didn't say much because I have a lot of slides on the simplified integration and let's talk about this now.

So how function works. Function is a piece of code, we already said that, but in order to execute that piece of code you need something called trigger. A trigger is an action that will involve this code and will pass some basic information to this code in order to run and of course code when it's done it has some sort of an output because why would you run it if it didn't have an output.

So the simplified integration is this part where binding to triggers inputs and outputs is very simple. For instance you can bind to a blob storage, so you can trigger a code whenever there's a new file available on a blob and you can maybe process that file and put it back on a blob storage. What is great here is that you are not limited to one trigger and one output.

. . or well trigger can only be one.

There's always one trigger, but you can also have multiple inputs so you can maybe grab additional data from your cosmos DB while processing this blob storage or maybe you can grab some additional info from the queue store and this is not where it ends, because you can also have multiple outputs. So maybe you process this file and grab some information from the queue now you can also output this to the blob storage, maybe save some additional logging into another blob storage and put some events for other applications to know that your finished processing on the event hub. So all those integrations are very very easy and I will show you why.

So let's grab the most simple example, so we're processing data from the blob storage and we want to output into the blob storage. How do we do this? I will use a DotNet Core as an example, but it's as easy in any other language as it's in DotNet Core.

You just grab a documentation and check what's the difference but the principle stays the same. So this is the piece of code that grabs the file from the blob as a trigger. So you have a blob trigger.

. . defined here and you do it in a way that you pass a parameter and you specify blob trigger.

That tells our function that we are triggering every time there's going to be new file on the blob storage. Second of all you specify in which container should you check. In this case it's going to be "sample-workitems".

So function will check whenever there are new files in this container and trigger whenever new file appears or is modified. Next. .

. You have something called expressions, so in this case use expression to grab the name of the file that is being processed. What is good here is that you can use this expression to pass the name of that file into a variable of the same name.

That means in this name variable right now in this parameter, You will have the name of the file or actual full path to the name in that variable. Next and lastly for this trigger you need to define a variable that you will put your contents of the file in. In this case it's a stream so we're going to put the file and all its contents in "myBlob" parameter, and lastly if you want this output you just add additional line saying "Blob", this is no longer trigger switch, it's just a blob.

You specify the container name, You specify the file access which is in this case writing because we were processing the file. And you can just type a "blob. copyTo(outputBlob)" and this is with.

. . one line of code you're making a copy of blob into additional container into additional storage.

This is as easy as you see. You just type in one binding, because every this line that you see here, "BlobTrigger" "Blob", those are bindings. So just give one line of binding and just type your code and it does all the connectivity, all the file.

. . uploading, downloading, all those kind of actions for you and it's as easy as it gets for any other binding, for any other service.

So if this is so easy what kind of triggers and bindings do you have available at hand. There's quite a lot of those. I will show you the brief list.

So first of all look at this list and notice that there's first of all two versions of the Function Apps. Version point 1 and version point 2. I would say go for version point 2, because it's that direction that Microsoft is going and it's probably gonna be long-term living support here.

Much longer than a version first and there's a lot of new features coming in to point out that are not available in point 1. But also notice that all those services not always can be also input and output because of those. .

. how those services work. .

. best example of this is even grid on the left hand side because it can be a trigger but it cannot be output or input. So you can trigger your functions based on the events from the event grid, but you cannot output into the event grid.

. . yet.

So you have of course Blob storage, Cosmos DB, Event Grid, Event Hubs, HTTP and web hooks; those are standard this is not a service binding this is just a binding for you to create your HTTP RESTful services. You also have integrations with Graph. Graph is a.

. crazy good API delivered by Microsoft to manage all things about Office and Azure Active Directory, so you have Excel tables OneDrve files, Outlook email, some events from the Graph you have tokens, but also you have Mobile App Service, you have Notification Hubs, Queue Storage, Send Grid, Service Bus, SignalR, Table Storage, Timer which means you can actually do scheduled processing and Twilio. So a lot of bindings for you to use and a lot of flexibility coming with them.

So let's go into the portal and start creating the service. In order to create new service you need to hit create resource and type function. .

. Hit create. You need to provide the name.

I'm gonna call it "a4edemoapp". I need to select a resource group I already have one existing, so I'm gonna choose that. I'm gonna leave OS as windows.

I'm going to leave consumption plan. Consumption plan is this serverless plan, which means you don't manage any servers. Azure will give you servers whenever there's a processing happening, whenever there's not it will take away those servers.

So have between 0 and 200 servers available at hand and of course either decides whenever you need those 200 servers or not. If you're going to be processing a lot of data Azure will keep giving you additional servers and your data will be processed faster. Next we need to pick a location.

I'm gonna pick North Europe, this is my go-to choice because it's the closest data center of me. I'm gonna choose runtime stack . Net Core I'm gonna choose storage.

Interesting. . .

why do I need a storage? Because everything that you're doing functions including functions code is stored on storage, as you can imagine since functions are serverless you don't have a server therefore, you don't have any place where you can put your code in and save your state. This is where storage comes in.

An entire code base of your functions and the state of your functions are saved on the storage. So whenever new servers are initialized they grab the code from this storage, and lastly you have Application Insights, a great service for logging and telemetry but this is not a part of the demo today. So let's hit create.

The deployment happens in about 2-3 minutes because three services needs to be deployed so I'm gonna speed this up So the deployment finished, so we can go to our resource group open it find a function up including that storage that we created and application insights I'm gonna go to App Service, and this is the default UI that you will be presented in that. . .

when you create functions. So let's go back to our presentation and I will talk briefly about the features that you can find here in the portal. So what are the top features?

First of all when you are presented with this you will have a list of the Function Apps and for each Function App you will have an overview table and a platform features tab. In an overview tab you have a most basic information about the Function App like the URL of the Function App, what is the pricing tier and App Service plan, what is the resource group that is hosted, what is the current status, which in our case it's running, but you also have. .

. something important in the platform features, because in the platform features you have much more options, like all the options coming from the App Service, but also, one key feature here is the Function App settings, I'm not going to talk about all those options here. Because they are coming from the App Service.

If you want to learn more about most of them, go to my video on the App Service, but for today we're just focusing on this one Function App settings. So in the Function App settings you will get the most basic information about the. .

. let's say crucial part of the environment setting. Like daily quota is here, the runtime configuration which is this 1.

0, 2. 0 version that we're talking about when we are talking about the bindings. You also have read-only mode here and if you want to change your application that no one can modify it you also have your host.

json file here, but I will talk about host. json file later on. .

. additionally when you have a functions already deployed in the functions tab you can find all those function you can change the state of each function you can either disable it or enable it you can create new functions from here of course this is not the professional way of developing functions but you can in fact develop functions in a portal. This is great for a quick prototyping but still considering how fast it is to deploy it from visual studio I would never use portal anyway.

So when you hit new function you'll be presented with the templates for this function you have HTTP templates, you have timer template service bus, queues, and a lot of more you just hit one of those provide some basic information and you will get the function like this. . .

so HTTP trigger function when you deploy it you will see something like this. This is the out-of-the-box template using CSX which is like scripting C# file. I would say it's not the best to develop production applications, but it's good for every now and then.

. . And of course you have an additional tab called "test", so you can quickly test your functions also in the browser.

So it's like a small integration developed an environment for you in the browser to do a quick POCs, quick testing and quick functions. Next in this function inside of it you have three tabs. One called "integrate", this is a visual way to add those bindings that we're talking about.

You have a trigger here, you can other inputs, multiple inputs or multiple outputs and for each you can provide a configuration. For instance when hitting on the input you will get the list of that standard input that you can use like a blob storage, table storage, authentication tokens from Graph, etc. Next you have a manage section In the manage section, you can manage keys.

What are the keys for the functions? When you create a function and you had this function code that we are showing at the top you had a get function URL button when you hit it if you would see something like this with the URL to your function but what you wouldn't see at first it does there's a very long code attached to your function this is authorization code that allows you to call this through the public Internet and you have also monitor tab. .

. in which you can see all the executions for your functions this is a very very small very basic feature is just a date operation ID duration code but if you want to see full telemetry for your data you just go to application insights since we provision this together and that's it in terms of portal features but one last thing that I want to talk about is this host configuration file. Because this host file that we are talking about in the function app settings is the file that controls how your entire functions work for instance one of the sections that you can apply there is HTTP section this is the section that will control how your HTTP trigger works first of all it defines the route it says that the prefix for the route is always slash API which is good to always notify your customers and your clients that this is the URL for the API you also have max outstanding requests count, this is how many requests can there be queued before your requests will start getting responses TooBusy from the service, and also you have max concurrent requests and this is the count of how many parallel executions for the functions can happen at the time in this case it's a hundred which means we can have 100 functions running at the same time so let's go further and talk about this file but remember this file is available in the function app settings if you're working in the portal this is place where you change it but if you're working with a code then this is going to be part of your code base in your project so let's go back to the portal since we've seen how to work with this, let's create a quick function so let's go to the function tab let's hit this button to create new function from the quick start we're gonna choose that we want to develop in the portal I'm gonna hit continue I want to create a web hook plus API which is this HTTP trigger so I'm going to hit create.

. . and in just couple of seconds I'm going to be presented with a standard template for HTTP triggers okay I've got it and notice that it is tiny bit different that what we were talking about because you have here "HTTPRequest" it's not "HTTPTrigger" and a.

. . this is simply because working with HTTP is tiny bit different than working with other triggers but don't worry about it this is the most simple version of the HTTP function that you can write, so you have some logging here that we've been processing the request this says that grabbed a URL parameter called name if there is some parsing and if there's no name in the URL return the message that URL needs to be submitted if it is say hello and name, so let's see if this works you can test it two ways you can either open this panel on the right hand side click on the test tub and send a request body or a URL parameter scroll down this UI is known that the best but there's a run button here executed and we got hello Azure.

. . so it works but you can also test it just by grabbing a URL yourself going to another tab pasting the URL hitting Enter of course please pass the name query string we didn't do that so let's do that so my name is Adam and hello Adam so you see it works and we got logs here we could console everything that we do we can see here quickly at glance so of course you could stay here and start the hoping here and notice how easy it is to actually create your HTTP type functions but let's be professional so let's go and create function code using Visual Studio Code so how do you do that first of all you go to your Visual Studio Code make sure that you are logged in and you have extensions called Azure account and Azure functions installed including all the CLI tools for the functions when you do you log into your functions and your portal and in your subscription you should be able to find the function that you created let's refresh so we have our a4edemo application this is all the function that i have access to so what we need to do right now is go to Explorer this is the empty demo folder and then I created and you need to initialize new project I do that by hitting F1 and typing functions so if you have an extension installed you see all those options here I will hit create function option it says that I need to initialize the project which I'm gonna say ok I want to use C# because today's demo is part of the .

net core I want to trigger let's maybe do a scenario where we're gonna trigger from the blob, we're gonna process this blob and output it back into the storage so I'm gonna hit blob trigger well the name is not the best but let's change it ProcessMyBlob. . .

so let's process my blob what is the namespace I'm just gonna leave it as default create local app settings JSON I'm gonna use this storage I need to create a what is the container name I'm gonna call it demo and for local development you need to select if you're using live storage account from Azure or if you're using local emulator I'm gonna choose local emulator because it's much better and what to do with the file that we're going to create opening current window it was quite few options to click at start but we're done and let's see what the template created for us first of all you hit here enter and here and here we see that have we have three parameters for blob so we have a connection name we choose the connection we have a demo so let's talk about what do we have here first of all blob trigger which means this function will run every time there's a new file this file has to be on the demo container on a storage that is supplied in this connection setting and the name of the file will be passed into name parameter so what we need to do here is we probably could just deploy this right now but what I want to do is I want to actually remove this setting because I don't want to create new storage account I want to use this setting use AzureWebJobsStorage so you can quickly change that by changing this connection name here so that means we're going to connect the blob but how to connect to this blob we're going to use connection specified by app setting called AzureWebJobsStorage if you want to talk about and here about the app settings go again to the video on the App Service Plan and App Service in general and you will see how this binding is done because this is also one of the features coming from the app service so we're gonna grab this connection string which means in the local development we're gonna use local storage in the portal we're gonna use the storage attached to our functions so let's hit save here let's do one more thing let's do a demo where since we're gonna be processing this file and we can already do something about it like I don't know. . .

grab the length of this file like var len equals this right so this is gonna grab the length of the file from our stream and put it in the length variable so if you want to output something into Blob again we need to go here the easiest is just copy this line and change few things about it so let's remove trigger because this is no longer trigger it's gonna be output lets outputs. . .

lets output something in two different container maybe call that container output let's leave the name as the same as the name of the file we started processing and let's change the variable to outputBlob so what do we do right now let's do most simple example where I'm gonna grab my blob type copyTo and let's copy it to outputBlob one thing that we're missing here is file access because for all the outputs and inputs besides the trigger we need to specify what is the file access that we're accessing in this case we want to write to the blob therefore we need file access write. . .

this should be fine and we should be able now to run this function I can run it locally or quickly deploy this to Azure, so let's hit a comment "dotnet build" after our function function is built we can quickly deploy this to Azure I'm pretty confident this will work so let's try it. . .

we go to our Azure extension we right-click on our application click deploy to function app it will say if you are sure that you want to override existing functions. . .

well I am sure. . .

so let's go for that and the first deployment takes about a minute or two so let's speed this up looks like we're done if this works we can probably go back to the portal and test it I'm gonna open my storage account into the blob service if you don't know storage accounts I have a great video on storage account introduction that also will be linked down in the comment section so feel free to check it out for now I'm gonna create two containers as we specified one for the input which is called demo and one for the outputs called output so if my function is working fine I can go to demo hit upload a file select one of that files maybe my file with my code now back to the blobs go to the output container hit refresh and then just couple of seconds we will gonna get our file here even before I stopped talking we already processed our file and I can open this file here and check that we have entire content of our file copied successfully to another container it was this easy to bind two blobs process something with them and output back to the blob storage and believe me it's as easy to bind. . .