Cannot import Python modules while using a SAM image.

[devmuch]

I am unable to import modules in Python.

Steps to reproduce:

1. Launch sam init
2. Enter the following choices:

1 - AWS Quick Start Templates

1 - Hello World Example

Use the most popular runtime and package type? (Python and zip) [y/N]: N

Which runtime would you like to use?
  16 - python3.9

What package type would you like to use?
  2 - Image

(defaults for remaining prompts)

Create a ./sam-app/modules/my_module.py with the following contents:

def create_message():
    return "Hello World"

Modify ./sam-app/app.py to contain the following:

from modules import my_module

def lambda_handler(event, context):
    return {
        "statusCode": 200,
        "body": my_module.hello_world()
    }

Build the function with sam build

Run sam local invoke

Results in:

{"errorMessage": "Unable to import module 'app': No module named 'modules'", "errorType": "Runtime.ImportModuleError", "requestId": "7eac3ff7-f94a-469e-9fa4-96d42b99eaea", "stackTrace": []}

Observed result:

2024-01-22 12:09:26,770 | Config file location: C:\Users\interim\Desktop\sam-app\samconfig.toml
2024-01-22 12:09:26,773 | Loading configuration values from [default.['local', 'invoke'].parameters] (env.command_name.section) in config file at   
'C:\Users\interim\Desktop\sam-app\samconfig.toml'...
2024-01-22 12:09:26,774 | Configuration values successfully loaded.
2024-01-22 12:09:26,774 | Configuration values are: {'stack_name': 'sam-app'}
2024-01-22 12:09:26,779 | Using SAM Template at C:\Users\interim\Desktop\sam-app\.aws-sam\build\template.yaml
2024-01-22 12:09:26,797 | Using config file: samconfig.toml, config environment: default
2024-01-22 12:09:26,798 | Expand command line arguments to:
2024-01-22 12:09:26,799 | --template_file=C:\Users\interim\Desktop\sam-app\.aws-sam\build\template.yaml --no_event
--layer_cache_basedir=C:\Users\interim\AppData\Roaming\AWS SAM\layers-pkg --container_host=localhost --container_host_interface=127.0.0.1
2024-01-22 12:09:26,801 | local invoke command is called
2024-01-22 12:09:26,804 | No Parameters detected in the template
2024-01-22 12:09:26,828 | Sam customer defined id is more priority than other IDs. Customer defined id for resource HelloWorldFunction is
HelloWorldFunction
2024-01-22 12:09:26,830 | There is no customer defined id or cdk path defined for resource ServerlessRestApi, so we will use the resource logical id
as the resource id
2024-01-22 12:09:26,832 | 0 stacks found in the template
2024-01-22 12:09:26,833 | No Parameters detected in the template
2024-01-22 12:09:26,849 | Sam customer defined id is more priority than other IDs. Customer defined id for resource HelloWorldFunction is
HelloWorldFunction
2024-01-22 12:09:26,850 | There is no customer defined id or cdk path defined for resource ServerlessRestApi, so we will use the resource logical id
as the resource id
2024-01-22 12:09:26,852 | 2 resources found in the stack
2024-01-22 12:09:26,853 | Found Serverless function with name='HelloWorldFunction' and ImageUri='helloworldfunction:python3.9-v1'
2024-01-22 12:09:26,855 | --base-dir is not presented, adjusting uri C:\Users\interim\Desktop\sam-app\hello_world relative to
C:\Users\interim\Desktop\sam-app\.aws-sam\build\template.yaml
2024-01-22 12:09:26,856 | --base-dir is not presented, adjusting uri . relative to C:\Users\interim\Desktop\sam-app\.aws-sam\build\template.yaml    
2024-01-22 12:09:26,870 | Found one Lambda function with name 'HelloWorldFunction'
2024-01-22 12:09:26,871 | Invoking Container created from helloworldfunction:python3.9-v1
2024-01-22 12:09:26,872 | No environment variables found for function 'HelloWorldFunction'
2024-01-22 12:09:26,873 | Loading AWS credentials from session with profile 'None'
2024-01-22 12:09:26,882 | Code None is not a zip/jar file
Building image.................
2024-01-22 12:09:27,273 | Checking free port on 127.0.0.1:7543
2024-01-22 12:09:27,279 | Using local image: helloworldfunction:rapid-x86_64.

2024-01-22 12:09:28,107 | Starting a timer for 3 seconds for function 'HelloWorldFunction'
START RequestId: 3a445e67-259f-41b0-a6a8-e2d3f9b8d579 Version: $LATEST
[ERROR] Runtime.ImportModuleError: Unable to import module 'app': No module named 'modules'
Traceback (most recent call last):
END RequestId: ff9d8eed-5ce7-44af-ac2b-27bbeb3fa574
REPORT RequestId: ff9d8eed-5ce7-44af-ac2b-27bbeb3fa574  Init Duration: 0.46 ms  Duration: 63.04 ms      Billed Duration: 64 ms  Memory Size: 128 MBMax Memory Used: 128 MB
{"errorMessage": "Unable to import module 'app': No module named 'modules'", "errorType": "Runtime.ImportModuleError", "requestId": "ff9d8eed-5ce7-44af-ac2b-27bbeb3fa574", "stackTrace": []}
2024-01-22 12:09:29,190 | [Container state] OOMKilled False
2024-01-22 12:09:29,425 | Cleaning all decompressed code dirs
2024-01-22 12:09:29,427 | Telemetry endpoint configured to be https://aws-serverless-tools-telemetry.us-west-2.amazonaws.com/metrics
2024-01-22 12:09:29,429 | Telemetry endpoint configured to be https://aws-serverless-tools-telemetry.us-west-2.amazonaws.com/metrics
2024-01-22 12:09:29,429 | Unable to find Click Context for getting session_id.
2024-01-22 12:09:29,431 | Telemetry endpoint configured to be https://aws-serverless-tools-telemetry.us-west-2.amazonaws.com/metrics

Expected result:

The function will run.

Additional environment details (Ex: Windows, Mac, Amazon Linux etc)

# Paste the output of `sam --info` here
{
  "version": "1.107.0",
  "system": {
    "python": "3.11.7",
    "os": "Windows-10-10.0.22631-SP0"
  },
  "additional_dependencies": {
    "docker_engine": "24.0.7",
    "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"
  ]
}

[hnnasit]

Hi @devmuch, thanks for opening the issue. The modules folder needs to be copied to the image as well. Here is a simple project that I have created based on the details you provided:
template.yaml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: >
  python3.9

  Sample SAM Template for sam-app-6592

# More info about Globals: https://github.com/awslabs/serverless-application-model/blob/master/docs/globals.rst
Globals:
  Function:
    Timeout: 3
    MemorySize: 128

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:
      PackageType: Image
      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
    Metadata:
      Dockerfile: ./hello_world/Dockerfile
      DockerContext: .
      DockerTag: python3.9-v1

app.py

from modules.my_module import create_message

def lambda_handler(event, context):
    return {
        "statusCode": 200,
        "body": create_message()
    }

Dockerfile

FROM public.ecr.aws/lambda/python:3.9

COPY ./hello_world/requirements.txt ./
RUN python3.9 -m pip install -r requirements.txt -t .

COPY ./hello_world/app.py ./
ADD ./modules ./modules

# Command can be overwritten by providing a different command in the template directly.
CMD ["app.lambda_handler"]

directory structure

.
├── README.md
├── __init__.py
├── events
│   └── event.json
├── hello_world
│   ├── Dockerfile
│   ├── __init__.py
│   ├── app.py
│   └── requirements.txt
├── modules
│   └── my_module.py
├── samconfig.toml
├── template.yaml

Let us know if you still have questions.

[devmuch]

Thanks for this. I naively assumed it copy the folder contents, but RTFM proves me wrong. :-)

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