AWS lambda get http method with Python

Question

I am having difficulty getting http method used in a call to aws lambda via api gateway. I created a REST api in api gateway, which makes a call to a lambda function. In the lambda function I want to have two functions, one for POST requests and one for GET requests. I am unable to get the method from event. In other threads answers are usually for javascript or java only.

I run the following curl command from my terminal: curl "https://myurl/endpoint" I also try to send a GET request via advanced rest client.

Here's what I'm trying to do:

def lambda_handler(event, context):

method = event['httpMethod']
if method == "GET":
    return get_function()
if method == "POST":
    return post_function()

Running the above code results in a keyError. I have tried this as well:

method = event['requestContext']['http']['method']

I tried printing out the event itself like this method = event. All I get from this is {}, both in the response and in cloudwatch.

How can I read the http method in a request

Can you add to your code `print(event)` and check in cloudwatch logs what is the actual structure of your event object? — Marcin, Feb 24 '21 at 08:10
I added print(event) and in cloudwatch logs I get {} only, nothing else — davidb, Feb 24 '21 at 08:13
You have to provide exact details of how are you using curl and how did you expose your function to the internet? Is it API gateway, REST API, HTTP API, exact settings? — Marcin, Feb 24 '21 at 08:14
Yes. Its the easiest and most common way of using rest api with lambda function. — Marcin, Feb 24 '21 at 08:39
I got it to work, had to change the response a bit but it is working now. Thank you for your input @Marcin — davidb, Feb 25 '21 at 01:22

score 1 · Answer 1 · answered Feb 24 '21 at 21:50

Below code should work in Python 3.7 runtime. Of course, you can improve the code but, it will give you what you are looking for.

    reqcontxt = event.get("requestContext")
    httpprtcl = reqcontxt.get("http")
    methodname = httpprtcl.get("method")
    print('### http method name ###' + str(methodname))

Thanks.

Hiren

score 1 · Answer 2 · answered Feb 25 '21 at 01:29

With help from @Marcin I understood that I had to tick 'Use Lambda Proxy Integration' option in integration request. Without it my request did not pass any method or headers data to lambda. It was either this or I would need to add some more code in my application to define the method but as I was using curl for testing I didn't add -X GET nor anything like that to the request.

AWS lambda get http method with Python

2 Answers2