Bug: sam local invoke - Failed to load

[f1-f12-projects]

Description: Created new sam project and replaced lambda_handler with flask_lambda. Unable to start the server due to various dependency issues.

Steps to reproduce:

1. Create new project with command:
   sam init —name xxxx
   Note: I can build and start the api.

2. Replace lambda_handler with flask_handler. Below is the code of app.py:

from flask_lambda import FlaskLambda
from flask import request, app

app = FlaskLambda(__name__)

@app.route('/hello')
def hello():
    print (request.args.get('name'))
    return "Hello World"

3. Downgraded version of werkzeug to 2.0.3 due to dependency issues (BaseRequest).
4. Update Requirements.txt as below:

requests
flask_lambda
flask==3.0.3
Werkzeug==2.0.3

4. start build —> Successful
5. start local invoke - Out of sam local invoke:

Invoking app.app (python3.12)                                                                                                                                                             
Local image is up-to-date                                                                                                                                                                 
Using local image: public.ecr.aws/lambda/python:3.12-rapid-x86_64.                                                                                                                        
                                                                                                                                                                                          
Mounting ProjectFolder/aws/vk-aws-flask-testing/.aws-sam/build/HelloWorldFunction as /var/task:ro,delegated, inside runtime  
container                                                                                                                                                                                 
START RequestId: 3ce5e5c2-4b90-410c-b117-c20db0700ec8 Version: $LATEST
{"timestamp": "2025-01-10T23:20:02Z", "log_level": "ERROR", "errorMessage": "Unable to import module 'app': No module named 'flask_lambda'", "errorType": "Runtime.ImportModuleError", "requestId": "", "stackTrace": []}
10 Jan 2025 23:20:02,509 [ERROR] (rapid) Init failed error=Runtime exited with error: exit status 1 InvokeID=
10 Jan 2025 23:20:02,514 [ERROR] (rapid) Invoke failed error=Runtime exited with error: exit status 1 InvokeID=2c5f0794-306b-4c16-baaa-7ed4411562b8
10 Jan 2025 23:20:02,515 [ERROR] (rapid) Invoke DONE failed: Sandbox.Failure
{"errorMessage": "Unable to import module 'app': No module named 'flask_lambda'", "errorType": "Runtime.ImportModuleError", "requestId": "", "stackTrace": []}
koteswarvijay@Vijays-MacBook-Air vk-aws-flask-testing % 

sam -info output:
{
  "version": "1.132.0",
  "system": {
    "python": "3.12.4",
    "os": "macOS-12.7.6-x86_64-i386-64bit"
  },
  "additional_dependencies": {
    "docker_engine": "27.4.0",
    "aws_cdk": "Not available",
    "terraform": "Not available"
  },
  "available_beta_feature_env_vars": [
    "SAM_CLI_BETA_FEATURES",
    "SAM_CLI_BETA_BUILD_PERFORMANCE",
    "SAM_CLI_BETA_TERRAFORM_SUPPORT",
    "SAM_CLI_BETA_RUST_CARGO_LAMBDA"
  ]
}

Updated templates.yaml:

Resources:
  HelloWorldFunction:
    Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
    Properties:
      CodeUri: hello_world/
      Handler: app.app
      Runtime: python3.12
      Architectures:
      - x86_64
      Events:
        HelloWorld:
          Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
          Properties:
            Path: /hello
            Method: get

[roger-zhangg]

Not sure if this helps, could you check if the following handler code works?

from flask import request
from flask_lambda import FlaskLambda

app = FlaskLambda(__name__)

@app.route('/hello')
def hello():
    print (request.args.get('name'))
    return "Hello World"