Create a Serverless .NET Core 2.1 Web API with AWS Lambda

In this video, we look at how we can build a .NET Core 2.1 WebAPI before deploying our application up to AWS Lambda and verying we can each our endpoints.
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[@johnalexander2003]

Hi Daniel, I have to say your tutorials are perhaps the best I've found on these topics. I'm a seasoned mobile/desktop developer, but I've always avoided "web" stuff. Now I want to get into it, and your tutorials using net core and aws are amazing! Thank you. One suggestion would be to expand this tutorial to include creating a serverless lambda api that accesses an aws rds (such as mysql) as well as storage for file uploading/downloading. Show how to create a simple CRUD controller/service for the database and another for simple file uploads/downloads. With that framework, a developer can really do pretty much anything and build from there. Again, thank you for the wonderful tutorials!

[@DanielDonbavand]

Thanks John, I will hopefully find some time this year to get more videos out around what you have suggested. Thanks again, these comments certainly put a smile on my face.

[@gauravkothari1919]

Thanks Daniel for the great tutorials you make and all the hard work you put in for making the videos. Really appreciable.

[@OlegWin355]

Wow! Thank you so much!!! In 17min you were able to cover so much, unbelievable. The best educational video I have ever seen. I am definitely subscribing to your channel.

[@DanielDonbavand]

Awesome, really pleased to hear.

[@tiagopala707]

Nice video Daniel, you've helped me a lot!

[@DanielDonbavand]

Awesome, glad to hear.

[@shivawahi4489]

This is exactly what I was looking for. Thank you so much

[@davidrobison899]

Thanks big time Daniel. Terrific tutorial. I hope you'll keep making similar videos.

[@shrinivaskottawar4872]

Thank you so much Daniel excellent explanation.

[@foggzie3502]

Can you add a full list of policy permissions needed for the account profile used to publish? I had to repeatedly attempt to publish, wait for a permissions failure, then update my permissions until the deployment was successful. I figured it'd be straight-forward but ended up needing different Lambda, IAM, Cloudformation, and Apigateway, permissions. Otherwise, this video was great and exactly what I was looking for; I'm slowly migrating away from my old LAMP stack ways and this was a huge first step. Thank you!

[@persephione]

Awesome! Very informative video. Got mine to work! Thanks so much!

[@anikdas7434]

Thank you so much for your wonderful tutorial.

[@danzaverdk]

Wow!!!! Thanks!!! I needed this kind of this tutorials

[@DanielDonbavand]

Awesome, I'm glad it helps. Thanks for watching.

[@danzaverdk]

If i may suggest for future video consideration, i think it would be awesome to continue this as a series like creating a razor page and then consuming the api you have created now to the razor page and then deploying it also in aws.

[@kirankalvagadda3075]

What is performance hit of loading asp.net core for every request.

[@akshayrb8410]

great job mate, worked superb on first try. thanks... it helped a lot.

[@cnikolov]

Quick Question, you've made 3 requests to your application. Adding 2 products and then displaying them. I thought everytime you invoke lambda function it would be. spinning a new instance of your application. but looking at this obvously it doesnt. Could you explain a bit more how the lifetime of the application works? Does that means that the function is constantly running like EC2 machine ? Also what is your opinion for a simple web api application like yours, in terms of cost between EC2 and Lambda? I am a huge fan and spent hours in your SQS Course.

[@kirtibhardwaj609]

Thank you!...Great learning from this video!!

[@rajkumar-oy3ni]

you are awesome, with clear example

[@mariodiaz4355]

Great explanation

[@OlegKosmakov]

Correct me if I'm wrong. Doesn't AWS start new environment for each lambda execution? How is it stateful then? As far as I understand it may reuse the same environment if you make consequent requests fast. Is it what's going on in your demo?

[@bradwebber]

I was wondering the same thing. I think what we are seeing here is Lambda's container reuse (aws.amazon.com/blogs/compute/container-reuse-in-lambda/).

[@hkshambesh88]

top guy!! thanks for the quick workthrough

[@alainelemia9925]

How do you state the stage of the project when publishing to lambda? And how to just update and republish?

[@JesusLopez-es4to]

Thanks Daniel Very helpful tutorial

[@chitrapatel3164]

Many thanks, Amazing work.

[@l2hetoric]

Great video, but the tricky part (at least for me) is resolving cors issues when accessing from a website (hosted through S3 and Cloudfront) Could you share how to resolve the no allow origin access headers error from a cors request? (More specifically a post request to the API)

[@gowthamanprabhu4869]

I believe you need to setup CORS in starup.cs and use include [EnableCors("CORS")] below [ApiController] and also for each controller function...

[@shaleenshuklass]

Getting error " Severity Code Description Project File Line Suppression State Error CS0246 The type or namespace name 'Amazon' could not be found (are you missing a using directive or an assembly reference?) LambdaShoppingListWebAPI C:\Users\user\source epos\LambdaShoppingListWebAPI\LambdaShoppingListWebAPI\LambdaEntryPoint.cs 28 Active"

[@abidshaik9614]

Daniel, In AWS's API Gateway portal we have a way to TEST. How can we invoke a single method out of /{proxy+} from our .NET Core API ? Like test ControllerName/ActionName/Param

[@divyatirthadas]

Excellent & thorough one

[@shomagujjar7471]

Great tutorial!

[@jagadeeshwargunda8739]

This is very helpful, thank you.

[@zaccharles]

Great video, thanks :)

[@eams]

How did the shopping list item get stored? Wouldn't the dictionary be empty on the subsequent get request since the lambda is stateless?

[@kirankalvagadda3075]

Thanks, IT was very helpful.

[@josecalvo6707]

Thank you for your informative and helpful video Daniel. What I don´t understand here is why are you using an Interface for the ShoppingListService?

[@ervinarucaj548]

Very good job. Can you do another tutorial? Create a .net core web with just an index page. The index can have a Name TextBox, a Quantity Textbox (TextMode="Number")., an "Add" button where you are calling this WebApi AWS, and showing the values into a gridview? I want to see how you can call an aws webservice via .net core. Best regards and thanks :)

[@davidwright2153]

Hi, is there a way to configure CORS in the serverless.template file?

[@MITHUNROYabir]

Awesome. Be like that. I want to learn industry standard norms of Rest API project architecture in CORE. If you have any suggestion to how I should structure my projects files..

[@nbl23]

Would have been nice to have some information on the s3 bucket creation - like whats the need for it and how its part of the lambda function call.

[@DanielDonbavand]

Yip, fair, thanks for your comment, I'll try include these types of things in up and coming videos.

[@smithasencios9918]

Thanks Daniel, what permissions the users needs?

[@VimalKumar-rk3pw]

While pushing to Aws lambda at the time am getting error nuget.target(144,15) error. There is no host name for nuget.target file.

[@CoskunCaner]

that was very helpfull, thanx for your all efforts. i am wondering about AWS Cognito usage in this workflow. how can we accept only cognito authenticated users on our controller-methods? pls make a video about that. also an EF example on AWS would be helpful, too

[@FuzzPiAndFacial]

From Postman im getting 415 Unsupported Media Type, i thought it was related to the conent-typeheader and set it to application/json which is missing in postman. but now im facing another error, when i call the post the AddItemsToShoppingList receives a null.

[@muertaqueen]

thanks for the superb tutorial. Just a question, to the data is stored in the program memory (as it was in the dictionary), and not database right? But in a real life situation, data should be fetch from a database right?

[@DanielDonbavand]

100% this was only meant to be used as a demo.

[@bndnetworks1951]

whats the difference between using Lambda vs ElasticBeanstalk

[@AnshCollections]

Can you please explain , how can i deploy lambda if I dont have Window Visual Studio which has a advantage of AWS toolkit. How to do it on mac?

[@felipefreire665]

Good Morning Daniel Donbavand; Did you use the default serverless.template from Visual Studio project template aws? If not used could make the template available? Because mine didn't create the default url in the post, so I don't know how to test in aws.

[@jejejeueuue]

Nice one...better if you could add link to the downloadable source code of this example

[@johnnguyen1655]

Thanks Daniel for great video, BTW could you please let me know if you have any video about load balancer for serverless application in order to avoid down time when redeploying. Thanks!.

[@leandrobarros4682]

Hi! Don't you make more videos?

[@ankitshah2270]

Hi Daniel, I'm not able to see the methods in Amazon API Gateway --> Resource section. Basically, it should show the methods of the controller in Resources section. Do I need to add something else in this case?

[@irisgroup]

Awesome tutorial. Thanks a lot =) Can we use EF like as usual ? no problem right ?

[@maha2818]

Thanks daniel. Can we read data from S3 excel file in .net core WebAPI. If can please add videos. Thanks

[@zoran123456]

thank you. So why do I get 2 endpoints, essentialy the same but one with {proxy} suffix? What's the point in that?

[@gowthamanprabhu4869]

This is a stateless application yes? How come data (bread and milk) is perpetual across multiple API calls i.e POST and then GET? Each API call will spawn a new instance of this ASP.NET Core API build yes?

[@DanielDonbavand]

The dictionary I've used to store the shopping items is only for demonstration purposes. If you were creating a production application, you would need to use something like dynamodb, SQL. Each api call might or might not spin up a new instance, depending on how many requests are being made or how long ago the request where made I.e the previous app might have spun down.

[@ronanduffy303]

Hi Daniel, would it be easy to make a basic form on a web app to use to API?

[@sharathkumarputta9112]

This is nice Video. Thank you!!!

[@РусланСайфуллин-у4л]

hello, please take a short video, or describe, how to publication the WEB API on IIS to asp.net core 2.1-2.2.

[@irisgroup]

I got forbidden I tried a lot but couldnt find a solution {"message":"Forbidden"} Any idea

[@Siipe]

VERY USEFUL tutorial dude.. but I honestly think you should consider improving your accent.. :/ for non-native english speakers like me, it was very hard to understand..

[@Siipe]

@@laikaboss8494 silence yourself mate.. non native speakers, like me, are often saying sorry for our "bad english", but we are actually doing 95% of the job to keep the conversation up.. while most people like you don't give a shit about learning other languages nor about speaking a little slower to help

[@rp962]

good one buddy

[@vikasgargcs]

Can you please let me know what database you are using to store data and how you connect with that database Thank you

[@DanielDonbavand]

Hi Vikas, this video doesn't cover connecting to an actual database.

[@VanFS3K]

Hmmm, but will lambda services handle the view as well? I see you using the M and C from MVC. What about the view?

[@DanielDonbavand]

Hi VanFS3K, it can but I haven't added it in this tutorial.

[@VanFS3K]

@@DanielDonbavand I think thats where I'm the most lost. We have a MVC asp net core 3.0 site working, and we are thinking about porting it over to serverless, but I'm still trying to figure out how to split the site up into micro services, or if that's even the best way to go about it.

[@DanielDonbavand]

@@VanFS3K that's such a tough question for me to answer without knowing a lot more details about the solution, project etc. I'd suggest having a good read around about positives and negatives of using lambda for and MVC app.

[@VanFS3K]

@@DanielDonbavand I'll keep researching, thanks for the replies. Have a great holiday.

[@brockastis]

Thanks mate

[@jonathancg2161]

Daniel, I am developing an AI program right now, but I have one problem and I'm not sure how I should handle it: I am using 1 SQLite database and I'm loading the data manually (SELECT * FROM ...) into public static variables that are Dictionaries. Then I use those Dictionaries in a multi-threaded environment in read-only mode (so it's correct since I don't modify the data). But now I want to migrate this process to Amazon Lambda. The thing is, I'm not sure how static variables are handled here? Loading the whole database into the dictionaries takes around 30 secs, and I can't afford to wait this amount of time every time I call a lambda function (I can afford it at the beginning of the start of the web app, but after that, I cannot). I would need to load the database as soon as the ASP Net Core app is opened and keep it somewhere in "persistent" memory. I never modify the data, it's read-only 100% of the time. So I thought about doing it like this: - Load database from Amazon S3 - Take every data from database and load it into the dictionaries (already done) - Use the dictionaries (that are public static variables) into my functions (already done, I'm just not sure about memory management in Amazon lambda...) My program will call around 1k lambda function, if that can be useful to you. But liek I said, I'm not sure if using the public static variables are persistent here... Any tips on where to get this kind of information? Or if you know the answer... It could be very appreciated since I have been searching for hours now lol Btw, I thought about using Redis, but Redis is 1 vCPU and as you can see I call around 1k lambda function, so I really doubt 1vCPU will help me to obtain a result in less than 10 seconds (for every function call, there is around 1k iteration * around 50 states, so 50k look up in dictionary * 1k lambda functions). Plus my database is only 238 MB, using Redis for this use case seems overkill (and expensive...)

[@jonathancg2161]

By the way, I didn't say it, but your tutorials are AWESOME! I hope you'll release your course on Udemy or something like this because I would honestly pay for this! And so many other developers... The learning curve is very hard at the beginning and the documentation is "messy"... There lots of stuff to understand especially in the architecture or in Asp DotNet framework specifically, so having tutorials like this is a big plus... Keep doing them :) Jonathan

[@jonathancg2161]

After thinking about it, maybe what I actually need is an EC2 and not Lambda...

[@DanielDonbavand]

Hey, sorry it's taken me a while to get back to you. I've replied through email since it's a pretty big question.

[@roccocastoro1]

@@DanielDonbavand I'm interested in how this is handled as I've created several Lambda Functions to store Alexa skills, and noticed sometimes my data is persisted in the lambda environment and sometimes it's gone. I've remedied this by using d.b. for persistence but still interested. great tutorial

[@ManUnitedTribe]

Thanks for the tutorial...!!! :) How do I configure my Visual Studio to work with AWS?

[@DanielDonbavand]

Hi Pratik, you should be able to install the relevant nuget packages that you need. You can also download and install the AWS Toolkit for Visual Studio aws.amazon.com/visualstudio/

[@BarrazaIvan]

I am getting a 400 Bad Request when performing a POST. The code seems identical to the video, but the results are not. { "Name": "Milk", "Quantity": 1 }. I placedbreakpoints on each of the public methods of the ShoppingListController but only the constructor one is hit. After that... nothing. When I do a GET, the breakpoint in the GetShoppingList method is hit. For grins, I performed a DELETE and the same thing happened as in the POST call. How can I debug this?

[@DanielDonbavand]

Hi Ivan, That does sound like the input you are trying to pass in, is not valid. Can you confirm you have two properties in the ShoppingListModel a string named Name and an int named Quantity. I know you have mentioned you added break points, can I confirm you have added a breakpoint on the first line in the method AdditemToShoppingList on the ShoppingListController class? The reason I ask is that I would expect a 404 - Not Found if the controller method can't be found, so it sounds like the method can be found, but the input that you are passing in isn't being picked up. If the you do hit the breakpoint then confirming that the parameter 'shoppingList' has the values populated would be good. Failing this, feel free to push your solution up to github and send me a link. :)

[@BarrazaIvan]

@@DanielDonbavand My ShoppingListModel has two public properties; string Name and int Quantity. I re-created the project a number of times and I still get the same error. I am not sure what I am missing. It must be something simple. What would be the best way to debug this?

[@BarrazaIvan]

@@DanielDonbavand By the way, I did have the breakpoint on the first line in the method AddItemToShoppingList. I will work on providing you a link to github.

[@DanielDonbavand]

@@BarrazaIvan want to push your code up to a Github repo, I'll pull it down and have a look for you :)

[@andyliu1210]

Hi, are there any specific settings which I need to configure before publishing to Lambda functions? I have followed exact steps in your tutorial, but there's no function created after successful deployment. Great video though. Thanks.

[@DanielDonbavand]

Are you getting any errors when trying to publish your application?

[@andyliu1210]

@@DanielDonbavand hi, I didn't get any errors. The screens are identical to your videos. When I log into aws console, I couldn't see any functions.

[@DanielDonbavand]

Can I confirm that you are in the correct AWS Region? I assume you only have one AWS account and that is the account you are publishing to?

[@andyliu1210]

That's correct. I'm only using EU(London) as my region for everything.

[@DanielDonbavand]

If you are able to push your code up to BitBucket or GitHub I can take a look, see if I can see anything going on from my end.

[@developertester722]

I was getting error when build the solution "Package Amazon.Lambda.Core 1.0.0 is not compatible with netcoreapp2.1 (.NETCoreApp,Version=v2.1). Package Amazon.Lambda.Core 1.0.0 does not support any target frameworks."

[@DanielDonbavand]

Hi, it sounds like you need to update the 'AWS Toolkit for Visual Studio 2017' inside visual studio, head along to the Tools - Extensions and Updates menu, then search for "AWS Toolkit for Visual Studio 2017", ensure this has been updated to the latest version

[@developertester722]

Thanks for you reply, But Latest version of AWS Toolkit is already updated.

[@DanielDonbavand]

If you are able to push your code to either BitBucket or Github I can take a look for you.

[@developertester722]

@@DanielDonbavand i am just creating new project and when i build got the error but when i tried on different machine it works after that i reinstall vs but got the same error

[@DanielDonbavand]

If it works fine on a different machine, it sounds like there might be a conflict between versions. You could try uninstall all .NET Core and AWS SDKs, search the internet to make sure you get rid of all versions completely, before reinstalling. Failing that, you might have to contact AWS themselves and raise and issue with them.

[@avinashprabhakar7367]

Hi I am getting {"message":"Missing Authentication Token"} when I try going to link/Prod on the browser. When I try link/Prod/v1/shoppingList I get a 500 error. What could be the cause of this? I followed all the steps in the tutorial.

[@DanielDonbavand]

Hi Avinash, it's really hard for me to tell what is going on without seeing your code or a full stack trace. You will need to try and debug the code to try and work out what area of the code the 500 is coming from. You could add some try/catch's around the code to give you some better exception messages.

[@avinashprabhakar7367]

Thanks Daniel! I have managed to resolve it. Great video btw.

[@AngeloCostanzo89]

@@avinashprabhakar7367 Hi Avinash, i have the same problem, how did you resolved it? Thanks ;)

[@avinashprabhakar7367]

@@AngeloCostanzo89 Hi Angelo. It has been a long time since I looked at it so I am not sure exactly what was wrong. The problem with the AWS Lambda is that it does not useful error messages. The {"message":"Missing Authentication Token"} error is not usually because of some authentication error. It could be due to some syntax error or compiling error in the code itself. To get proper error messages to see what went wrong, you have to check the cloudwatch logs

[@AngeloCostanzo89]

@@avinashprabhakar7367 Solved! The problem was relative to the framework version. ;)

[@MrSuperwalnut]

Hi Daniel, how do you turn on/off the authentications?

[@MrSuperwalnut]

i am getting {"message":"Missing Authentication Token"}

[@DanielDonbavand]

Have you checked the serverless.template file in your solution, confirm that you haven't got anything setup in there? i.e Polices for this example should be set to AWSLambdaFullAccess

[@shailendrarampal7165]

Error while publishing on AWS lambda: 14-02-2019 14:06:27 AWS::Lambda::Function AspNetCoreFunction shoppinglisttest-AspNetCoreFunction-1OG80SANPB81G Please help !! Using: Visual studio 2017, .Net Core 2.2, AWS toolkit for VS2017

[@DanielDonbavand]

Hey, sorry but I can't work out what the issue is from what you have shown me. I would need more information.

[@shailendrarampal7165]

@@DanielDonbavand Hi, The api is working perfect locally but when i tried to publish it on AWS Lambda, it fails on publishing.The error is : Function not found ! Function Name : Function AspNetCoreFunction shoppinglisttest-AspNetCoreFunction-1OG80SANPB81G I hope this help !

[@jonathancg2161]

@@shailendrarampal7165 .Net Core 2.2 is not supported in Amazon Lambda.

[@shailendrarampal7165]

@@jonathancg2161 Thanks , I uninstall .Net core 2.2 and install 2.1 But the same error !!

[@jonathancg2161]

@@shailendrarampal7165 You need to update your project version aswell. I would recommend you to just create a whole new project in dotnet core 2.1. I'm guessing your project is very small, so I would do that if I were you instead of modifying it directly. It will be easier for you imo.

[@SukhrajMohammad]

For AWS with .net core, you can find series on my channel...

[@shailendrarampal7165]

HI, Can i change the name of webapi URL ?

[@DanielDonbavand]

This youtube video might help kzbin.info/www/bejne/hn7XhZ5-mtmUnZI

[@HumbertoPereira1994]

yes you can... you can set this up in the configurations inside your aws account in the ApiGateway section

[@BarrazaIvan]

The actual response I get is { "": [ "The input was not valid." ] }

[@DanielDonbavand]

It sounds like something isn't right with what you are passing into the service. As mentioned below, if you push your code up to a GitHub repo, then I can take a look for you.