Aws-toolkit-jetbrains: Cannot find handler .. in project when not using lambda_handler as a function

[Niggggggo]

Describe the bug
I cannot run my lambda function locally because the handler cannot be found.

To reproduce

1. Use example from here
2. Add run configuration (AWS Lambda -> Local)
3. Set runtime, Credentials and Region
4. Set Handler to "app.lambda_handler"
5. Error: Cannot find handler 'app.lambda_handler' in project.

Expected behavior
It should run the function specified in the lambda_handler variable, see second screenshot

Screenshots

Your Environment

• OS: Windows 10 Pro 1809
• JetBrains' Product: PyCharm Professional
• JetBrains' Product Version: PyCharm 2019.2.1 (Professional Edition), Build #PY-192.6262.63, built on August 22, 2019
• Toolkit Version: 1.5
• SAM CLI Version: 0.21.0
• Python Version: 3.7

Additional context

[OscarVanL]

Can you show your project's folder structure in the Project window?

[Niggggggo]

Can you show your project's folder structure in the Project window?

Of course, see here:

[abrooksv]

Is there a requirements.txt file somewhere?

[Niggggggo]

Is there a requirements.txt file somewhere?

Yup, if you look in the screenshot above it's in the hello_world folder

[OscarVanL]

I think the problem is that your local configuration's Handler isn't taking into account app.py is inside the project_directory/hello_world folder.

Essentially you're trying to run app.lambda_handler from the root project_directory rather than from inside hello_world.

Try changing it to hello_world/app.lambda_handler

[abrooksv]

It should be generating the code uri to be hello_world and handler is app.lambda_handle.

I thought I had a unit test for your setup. Will look into it.

[Niggggggo]

I think the problem is that your local configuration's Handler isn't taking into account app.py is inside the project_directory/hello_world folder.

Essentially you're trying to run app.lambda_handler from the root project_directory rather than from inside hello_world.

Try changing it to hello_world/app.lambda_handler

I'm not sure that is the issue, since it worked once I defined lambda_handler as a function

[abrooksv]

The handler should be relative to the requirements.txt

[hrabryi]

I also catch this error. Seems like a bug when try to use sb.lambda_handler() as lambda handler. I wrapped handler and it works for me:

def handler(*args, **kwargs):
    skill_handler = sb.lambda_handler()
    return skill_handler(*args, **kwargs)

[Niggggggo]

def handler(args, *kwargs):
skill_handler = sb.lambda_handler()
return skill_handler(args, *kwargs)

I can confirm that this works

Thanks a lot for the workaround!

[abrooksv]

We currently have the limitation that the handler has to be in your project's source.

[rstevens011]

I am trying to implement a custom resource for CFN and I am using this library https://github.com/ryansb/cfn-wrapper-python to wrap my create, update and delete handlers. The library expects you to set the handler like so:

import cfn_resource

# set `handler` as the entry point for Lambda
handler = cfn_resource.Resource()

@handler.create
def create_thing(event, context):
    # do some stuff
    return {"PhysicalResourceId": "arn:aws:fake:myID"}

@handler.update
def update_thing(event, context):
    # do some stuff
    return {"PhysicalResourceId": "arn:aws:fake:myID"}

The toolkit doesnt allow you to specify a handler this way.

[carltondickson]

In the process of trying to setup local debugging and seeing a similar error with nodejs

Error: Cannot find handler 'app.lambdaHandler' in project.

Initially I had used the following:

Runtime: nodejs12.x

Changed this to

Runtime: nodejs10.x

And it works fine now

SAM CLI, version 0.39.0

[cooper667]

In the process of trying to setup local debugging and seeing a similar error with nodejs

Error: Cannot find handler 'app.lambdaHandler' in project.

Initially I had used the following:

Runtime: nodejs12.x

Changed this to

Runtime: nodejs10.x

And it works fine now

SAM CLI, version 0.39.0

Same issue, and changing runtime also fixes it.

Project structure is:

 │   package.json
 │   index.js    
 │
 └───deploy
 │      │   sam.yml
 │   
 └───node_modules
        │   ...

[abrooksv]

Node 12 support is done in master but not yet released.

[InesCV]

It happened to me with my python3.7 project, turned out the python plugin for the community edition was blocking my Intellij Ultimate python plugin.

Solution:

• Uninstall PyCharm Community and Intellij IDEA Community
• Uninstall Python Community Plugin
• Restart Intellij

[snowe2010]

Node 12 support is done in master but not yet released.

Is node12 support done? I'm seeing the same issue, but changing to node10 doesn't work.

[plexus77]

@snowe2010 The problem for me ended up being the signature of the exports.handler function...

exports.handler = async (event, context, callback) => {

Doesn't work for me however when I change it to

exports.handler = async (event, context) => {

or

exports.handler = async event => {

I am able to run the function. I also have not marked any directories and in my template.yaml I have

Resources:
  ImageProcessFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: image-process
      Handler: app.handler

the function file relative to the project root is image-process/app.js

Hope this helps :)

[ivandjuricic]

I run into this too with python3.7 runtime! When specify lambda handler as a an object (lets call it obj) with implemented def __call__(event, context) I can't get valid run configuration.
Yet everything works if I just wrap that object into:

def lambda_handler(event, context):
    return obj(event, context)

[Ugbot]

Had this problem with the Hello world example on the python 3.8 runtime as well....
No changes to the generated source, it just can't find the handler...

[stedesDev]

Same for me very very frustrating... try every thing/path..
Also there is a in the configuration, if you have an error, even though you correct it, the create fuction still disabled
Regards

[abrooksv]

We current require being able to locate the Lambda handler in checked out source. This is a heuristic based system and does not cover all use cases.

We are slowly moving away from this hard requirement.

For run configurations using a template file, we no longer have this requirement.
For run configurations that specify a handler, this is still in place since we have not exposed a way for users to set the base directory we use to kick off a SAM build for.

[stedesDev]

I have folder/src/lambda_function.pyhttp://function.py

And the the lambda handler

What should I write in the config I have tried absolute/relative path...

Nothing work

Regards

Steph
Le 19 févr. 2021, à 4 h 41 p.m., Austin Brooks <[email protected][e-mail]> a écrit:

We current require being able to locate the Lambda handler in checked out source. This is a heuristic based system and does not cover all use cases.

We are slowly moving away from this hard requirement.

For run configurations using a template file, we no longer have this requirement.
For run configurations that specify a handler, this is still in place since we have not exposed a way for users to set the base directory we use to kick off a SAM build for.

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