majorcoder majorcoder - 11 months ago 132
Python Question

Using boto to invoke lambda functions how do I do so asynchronously?

SO I'm using boto to invoke my lambda functions and test my backend. I want to invoke them asynchronously. I have noted that "invoke_async" is deprecated and should not be used. Instead you should use "invoke" with an InvocationType of "Event" to do the function asynchronously.

I can't seem to figure out how to get the responses from the functions when they return though. I have tried the following:

"latitude": 39.5732160891,
"longitude": -119.672918997,
"radius": 100

client = boto3.client('lambda')
for x in range (0, 5):
response = client.invoke(

Even though I tell the code to sleep for 15 seconds, the response variable is still empty when I try and print it. If I change the invokation InvokationType to "RequestResponse" it all works fine and response variable prints, but this is synchronous. Am I missing something easy? How do i execute some code, for example print out the result, when the async invokation returns??


Answer Source

An asynchronously executed AWS Lambda function doesn't return the result of execution. If an asynchronous invocation request is successful (i.e. there were no errors due to permissions, etc), AWS Lambda immediately returns the HTTP status code 202 ACCEPTED and bears no further responsibility for communicating any information about the outcome of this asynchronous invocation.

From the documentation of AWS Lambda Invoke action:

Response Syntax

HTTP/1.1 StatusCode
X-Amz-Function-Error: FunctionError
X-Amz-Log-Result: LogResult


Response Elements

If the action is successful, the service sends back the following HTTP response.


The HTTP status code will be in the 200 range for successful request. For the RequestResonse invocation type this status code will be 200. For the Event invocation type this status code will be 202. For the DryRun invocation type the status code will be 204.


The response returns the following as the HTTP body.


It is the JSON representation of the object returned by the Lambda function. This is present only if the invocation type is RequestResponse.