Developing AWS Lambda Functions Locally in VS Code

n this video, I want to share the approach I use regularly to develop AWS Lambda functions (and other serverless projects) locally in VS Code using the benefits of AWS's secret sauce, SAM.
AWS SAM, or Serverless Application Model, is a framework that makes managing your serverless AWS service easy. Using the CLI was can create Lambda functions locally, test them, update them, and deploy them, all from our favorite code editor (mine being VS Code).
In this video, we'll create a simple AWS Lambda function locally and I'll show you how to manage it all from your local dev environment.
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[@viniciushenrique8211]

Now this is just amazing. I'll use AWS SAM a lot now, thanks! Only thing missing from this tutorial I think would be a small intro on managing Lambda Layers with AWS SAM too.

[@TravisMedia]

Noted

[@ramonpaolomaran2253]

19:02 and 19:58 You probably know now, but, for the people seeing that now, the AWS SAM CLI, have the command "delete" that delete all resources in the stack that you created. example: "$ sam delete "

[@TravisMedia]

Thanks Ramon!

[@Usernamesareoutdated]

thank you! I was dreading a new uphill battle, but you turned learning SAM into a water slide :D

[@veganlife9190]

Hey Travis, best sam tutorial I've came across. deserves the sub

[@TravisMedia]

Thanks!

[@sod16]

Awesome instructional video. This way of working helps cut out so much nonsense when it comes to working with lambdas!

[@asifrasool573]

Travis, you are just awesome. I had the issue with importing different python dependencies, mainly snowflake and sql alchemy, I tried a lot with layers and didn't want to shift to linux. I watched this video 3 days ago. But I was stuck in installing Docker, SAM CLI, and also I had Federated AWS Account. I fixed everything and came back to this video. You have saved me. Great tutorial and complete explanation. Thank you so much for this great content..

[@chrismacswan4766]

Oh my god thank you so much for that MFA script. You are a life saver.

[@thelonious-dx9vi]

Cheers, this is by far the best available explanation of this. But I really wish there was a more straightforward means of escape from the horrorshow browser IDE -- i.e. without SAM, CloudFormation, etc. I guess there's manually building and pushing zip files, but that's no bed of roses either. I seem to keep landing back in the console IDE when I just need to get something done with Lambda.

[@kofio7581]

Thanks Travis, Great Video! BTW - To delete the stack is: sam delete sam-app This was probably added post your video.

[@shantisagargebise2883]

Very well explained. Easy to understand and grasp.

[@raghavgautam3379]

Great man! Thank you so much! You are a great instructor.

[@TheMrbird123]

Thanks, this video was very helpful!

[@waldojams]

That's a neat and modern workflow! Wondering how debugging would work though. Cool thing about a fully functional approach is that it isolates dependencies and work with arguments, which generally make debugging easier. But I have no experience of working with this in a big environment. Looking forward to commit to use in in a bigger project.

[@waldojams]

Also interesting to think while I'm doing the research, for the cases where we'd like state coming from RDS (e.g. Postgres), testing locally might become a bit harder. Plus, there's the lambda high concurrency problem when it comes to opening/closing DB connections. At first glance, Lambda might look great for big projects, but when putting all elements on paper, things are not that simple :( I might stick to EC2 and sprinkle some Lambda functions to support it.

[@Imperfectwow]

cool video, one suggestion making more real world scenario lambda. for instance connecting to rds instance and running some query on db. or updating some paramter in paramer group. when you need to pack depedencis as well like boto3 or pymssql

[@szemeibon6258]

Thanks Travis for your great tutorial😃

[@adityatulsyan1359]

It was really helpful, please release more such videos. Thank You.

[@demiann4160]

This was just what I needed. Thanks!

[@TallMeDO]

game changer! thank you for this sir

[@kalmabrooks978]

Awesome tutorial, Which extension are you using on vs code for AWS auto complete and suggestions?

[@bordsUK]

Great tutorial. I am wondering what if you want to export existing lambda function and debug it locally in vscode. Would love to see that. Keep up the good work 👍

[@briandines]

Nicely done. Good clean explanation.

[@rugeneus]

Great! It is very clear explanation and very helpful!

[@fabiofusco6944]

Hi Travis, thanks a lot. Great tutorial. I have a question if you don't mind: how can I import dependencies in the local environment? Right now I use Layers, but they seem to not be imported locally. Thanks a lot!

[@RohitSharma-x3n]

That was very helpful

[@steveyoo9342]

travis, this was very helpful!

[@kaidobit6954]

the aws configure step + your script to get sts generating a token for you could be easily replaced using aws-vault, have a look at that

[@apartha77]

sam has cli command "sam delete"

[@ev_casey]

a quick sam -h shows can you can do a "sam delete" to remove all resources auto deployed :D .. Thanks for the video!

[@MegaJagveer]

Amazing tutorial! Very helpful

[@megalordification]

solid video - thank you

[@RandyL86]

Great tutorial! You were super clear and informative. Question for you: how do you get your terminal command line to bring up the past commands you've entered? That seems super useful. I searched but can't find how to enable it.

[@TravisMedia]

Thanks! Zsh autosuggestions. Check out the video I did a couple months back about the Oh My Zsh plug-ins, should be install instructions there. Actual here’s the link kzbin.info/www/bejne/gnayopyvrd1kbMU

[@shauncs]

spot on!

[@aviahh]

Great video it helps a ton. one question: if I want to do that with some Python libraries, where should I install those libraries, locally in the same folder (in your example "aws-sam")? something like pip install "library name" -t . ?

[@natarajpurudappa882]

sam delete --stack-name is to delete the stack

[@saeeduchiha5537]

In my environment, were devops team locks every thing and use TerraForm for deployment, is there a way to ONLY handle development/testing locally? Without needing the permission to create lambda

[@sushantasamantaray7140]

Amazing tutorial

[@alialouane7709]

Thanks man !

[@ksikluks]

Looks like aws-sam-cli doesn't provide an `aws` cli anymore. Only one called `sam` - which however doesn't come with a `configure` command. So stuck at the very beginning. Trying to follow along and see when it breaks…

[@ksikluks]

Ok, hasn't been mentioned in the video, but you need `brew install awscli` to get it.

[@miguellaurente5937]

Nice video, but what's about debuging. How can I do it?

[@karlang2637]

If you delete the stack, would the lambda functions get deleted too?

[@ganeshkharad]

what if there is an existing Lambda function and we want to import it to the local environment to work?? I don't see template.yml getting downloaded for that. there should be a way to generate it even if lambda is not created with SAM. if you know the answer do share it.

[@siddharthshukla3557]

we dont have access to AWS SAM CLI, is there any other way to develop and test on local?

[@mohammedbanabila8515]

thanks for video but i have question , can be use boto3 in sam app

[@josemadrid4343]

Can I test a CommonLayer locally using the same steps?

[@二一-g4p]

sam local invoke error:failed to deserialize response from rie. Help ❤❤❤❤

[@susmitdey9829]

I get this error while running sam local invoke, looks like an issue with the sam cli REPORT RequestId: eeaadf52-4164-4a85-b63e-8f2a69812e06 Init Duration: 0.80 ms Duration: 205.34 ms Billed Duration: 206 ms Memory Size: 128 MB Max Memory Used: 128 MB {"statusCode":200,"body":"{\"message\":\"hello world\"}"}Exception in thread Thread-2: Traceback (most recent call last): File "threading.py", line 932, in _bootstrap_inner File "threading.py", line 870, in run File "C:\Program Files\Amazon\AWSSAMCLI untime\lib\site-packages\samcli\local\docker\container.py", line 335, in wait_for_logs self._write_container_output(logs_itr, stdout=stdout, stderr=stderr) File "C:\Program Files\Amazon\AWSSAMCLI untime\lib\site-packages\samcli\local\docker\container.py", line 400, in _write_container_output for stdout_data, stderr_data in output_itr: File "C:\Program Files\Amazon\AWSSAMCLI untime\lib\site-packages\docker\types\daemon.py", line 32, in __next__ return next(self._stream) ... err, data = win32file.ReadFile(self._handle, bufsize) pywintypes.error: (109, 'ReadFile', 'The pipe has been ended.')

[@CommonSense11111]

How do you set a breakpoint?

[@hhjdkdnchidnd]

hi, how to debug the code?

[@musilicks]

a good developer doesn’t need to debug. they are 100% sure they’re code works. i don’t run or test my code, as I know it will work 100% flawlessly when deployed

[@BitBard302]

This content has my full endorsement! If you're interested, there’s a book I’d recommend. "AWS Unleashed: Mastering Amazon Web Services for Software Engineers" by Harrison Quill

[@wtf1379]

Do i have to run "sam build" every time i make any change to the app.py file? i mean when i run that it creates the entire image from scractch rigth? like it installs all my dependencies and such

[@TravisMedia]

Yes but only run it when you’re ready to push changes, not on every change.

[@wtf1379]

@@TravisMedia so to test locally I can just save app.py and test it with "sam local invoke" without having to rebuild every time? Thank you for the super quick answer btw ahah

[@TravisMedia]

@@wtf1379 sorry misread, yes I would build it again each time before invoking locally as well.

[@TravisMedia]

Build before invoking locally and build before deploying.

[@ksikluks]

`sam delete` to delete the whole stack

[@damiandanev9271]

A mock service... a waste of time really. Apart from a hardcoded hello-world, SAM is useless. You can't access any databases or any other service for that matter. Define your lambdas as docker containers and use AWS CDK, have your databases running in containers as well. I wonder how long will it take for SAM to be deprecated.

[@arianhojat9660]

Just curious how do you add env vars to VSCode to debug Lambdas? i have nonprod and prod AWS profiles i can switch in VSCcode to (my aws key/secret pairs). but lets say a nonprod lambda func has other env vars for dev vs qa vs stg env. I want to have a JSON file for each env to use in the nonProd account. Right now when debugging locally, I paste the env key/values under relevant launch.json area: "configurations": [ { "lambda": { "environmentVariables": { ...my Lambda function's key and values here... } } }] Is there a way to specify a file instead of hardcoding the env vars in there? i saw something about "payload": "json" option to use in the environmentVariables area , but not sure if its 100% related to the env params: docs.aws.amazon.com/toolkit-for-vscode/latest/userguide/serverless-apps-run-debug-config-ref.html