How to use aws-lambda-python docker image with example in VSCode for local development

Docker image: https://hub.docker.com/r/amazon/aws-lambda-python

This docker image lacks working example on how to use.

If you just want to test your lambda with this image locally, please read on.

Let's assume the following:

  • Your script is called `my_python.py`
  • The function in this file that you want to execute is called `lambda_handler`
Here is the docker command (I'm using windows):

docker run --rm \
-p 9000:8080 \
--mount type=bind,src=/c/projects/my_lovely_proj,target=/var/task \
amazon/aws-lambda-python \
my_python.lambda_handler

Brief explanation on above:
  • --rm : Remove the container after terminating the script (i.e. Ctrl + C in command line).  So you don't need to run `docker stop <container_id>` and `docker rm <container_id>`
  • -p 9000:8080: map the port of local machine 9000 to container port 8080.  This is super important and will be explained later.
  • --mount: Mount the dir to /var/task in container.  All lambda script will be executed in this /var/task dir
  • amazon/aws-lambda-python: the docker image name
  • my_python.lambda_handler: It is very confusing at first glance.  The format of this string is actually: <script_file_name>.<function_name_to_be_executed>.  By default your lambda function is called `lambda_handler`.  Which means if your function name is called `my_func`, this string will be `my_python.my_func`

Then you would see something like this:

23 Jan 2024 03:28:43,852 [INFO] (rapid) exec '/var/runtime/bootstrap' (cwd=/var/task, handler=)

And nothing return...

You don't know if this is working, you have no idea what is executed, and just simply nothing.


This docker image is actually provide a server-like instance, which means, you need to "call" its API in order to trigger the execution.

In other words, this is not "run a script in a mapped container and finish when done", but "run a server that host your script and you need to call it to execute it".

So what is the API?  The answer is in the above article.

Since I am using Windows + PowerShell in VSCode, here is how to call an API (similar to curl) in a separated shell (PowerShell or terminal):
  • Windows
    • Invoke-WebRequest -Uri "http://localhost:9000/2015-03-31/functions/function/invocations" -Method Post -Body '{}' -ContentType "application/json"
  • Linux
    • curl "http://localhost:9000/2015-03-31/functions/function/invocations" -d '{}'
As you can see, in order to execute your lambda script in the container, you need to "call" it as a REST API (In AWS terms, it is called "Invoke").  So if you see the word "invoke"/"invocation" or similar, it simply means "calling lambda API".

Then you would see result:

Now you know that your script is triggered/invoke/called successfully.

Then start your development now.

Hope it helps someone.

Comments

Post a Comment

Popular posts from this blog

TCPDF How to show/display Chinese Character?

Thanks to this article (in Simplified Chinese, updated new link), there is a way to embed a TTF that can display Chinese (Traditional and Simplify, and possibly Japanese). Environment:  TCPDF 6.0.020 PHP 5.3.8 Windows 7 The problem: If you follow this post that said: using cid0cs or cid0ct to display Chinese, it can display the character correctly, only to the extend that user installed a correct font package.  However, chances are other users who didn't install that package cannot view that PDF since there are several packages and versions of PDF viewer (mainly Adobe).  And even worse: even if user installed certain CJK font package, the PDF still not displayed correctly (show empty page). And according to the official TCPDF documentation about font : The fonts that could be not embedded are only the standard core fonts and CID-0 fonts . The solution: Again, thanks to the post above (in simplified Chinese), now developer can use a font that: Can display Chines
Read more

How to fix fancy box/Easy Fancybox scroll not work in mobile

Hi The Problem: If you are working on EasyFancybox or just normal fancybox JS , and you have this problem: In your iOS device when a popup is opened, if the page is too wide and your pop up cannot show all, when user taps and drag the screen, the background will be dragged instead of the pop-up content. To fix, add this in your CSS: -webkit-overflow-scrolling: touch !important; So which element should you apply it to? In Easy Fancybox, you will see these 2 lines: <div id="fancybox-content"........>         <iframe id="fancybox-frame" name............... Apply to fancybox-content, not fancybox-frame So in your CSS, it should be: #fancybox-content{         overflow: scroll !important;         -webkit-overflow-scrolling: touch !important; } It works for me, and I hope it helps someone also.
Read more

Wordpress Load balancing: 2 web servers 1 MySQL without any Cloud services

Image
This is the exact config that I need to configure a load balancing without other cloud services like Amazon, rackspace or GoGrid, completely customized. I put my question on stackoverflow.com but no luck, so I put it on Quora.com and immediately I got response: My Notes: The load balancer is done by my colleagues so I am not sure what is the config of it.  But one thing to note: Your LB should enable "session stickiness" so that the session will follow visitor.  By the way, I am using Round-robins. Session: Actually I did not use session, but it seems that other plugins (like WPML) will use it.  If I use Apache load balancer, when I go to wp-admin through load balancing IP, I will not able to login, given the username and password is the same.  I will be redirected to login page.  So ask your load balancer providers or check your load balancer config and see how to manage the "Session Stickiness" issue. Shared folder: your wp-content/uploads folder mus
Read more