Hello World, Unable to import module 'app': No module named 'app'

[sidsamant]

Description

Trying to follow the tutorial at https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/serverless-getting-started-hello-world.html#serverless-getting-started-hello-world-troubleshooting

Steps to reproduce

sam init --runtime python3.6

cd sam-app
sam build
sam local start-api

Observed result

In chrome, opening http://127.0.0.1:3000/hello
no data

In console,

Fetching lambci/lambda:python3.6 Docker container image......
2019-08-18 04:22:31 Mounting C:\Users\XXXX\sam-app\.aws-sam\build\HelloWorldFunction as /var/task:ro inside runtime container
START RequestId: 3ba1f0e5-fd1a-448d-86f2-c69f2927dbfe Version: $LATEST
Unable to import module 'app': No module named 'app'
END RequestId: 3ba1f0e5-fd1a-448d-86f2-c69f2927dbfe
REPORT RequestId: 3ba1f0e5-fd1a-448d-86f2-c69f2927dbfe Duration: 1 ms Billed Duration: 100 ms Memory Size: 128 MB Max Memory Used: 19 MB
2019-08-18 04:22:32 No Content-Type given. Defaulting to 'application/json'.
2019-08-18 04:22:32 127.0.0.1 - - [18/Aug/2019 04:22:32] "GET /hello HTTP/1.1" 200 -
2019-08-18 04:22:32 127.0.0.1 - - [18/Aug/2019 04:22:32] "GET /favicon.ico HTTP/1.1" 403 

Please provide command output with --debug flag set.

2019-08-18 03:52:40 Using SAM Template at C:\Users\XXXX\sam-app\.aws-sam\build\template.yaml
2019-08-18 03:52:40 Changing event name from creating-client-class.iot-data to creating-client-class.iot-data-plane
2019-08-18 03:52:40 Changing event name from before-call.apigateway to before-call.api-gateway
2019-08-18 03:52:40 Changing event name from request-created.machinelearning.Predict to request-created.machine-learning.Predict
2019-08-18 03:52:40 Changing event name from before-parameter-build.autoscaling.CreateLaunchConfiguration to before-parameter-build.auto-scaling.CreateLaunchConfiguration
2019-08-18 03:52:40 Changing event name from before-parameter-build.route53 to before-parameter-build.route-53
2019-08-18 03:52:40 Changing event name from request-created.cloudsearchdomain.Search to request-created.cloudsearch-domain.Search
2019-08-18 03:52:40 Changing event name from docs.*.autoscaling.CreateLaunchConfiguration.complete-section to docs.*.auto-scaling.CreateLaunchConfiguration.complete-section
2019-08-18 03:52:40 Changing event name from before-parameter-build.logs.CreateExportTask to before-parameter-build.cloudwatch-logs.CreateExportTask
2019-08-18 03:52:40 Changing event name from docs.*.logs.CreateExportTask.complete-section to docs.*.cloudwatch-logs.CreateExportTask.complete-section
2019-08-18 03:52:40 Changing event name from before-parameter-build.cloudsearchdomain.Search to before-parameter-build.cloudsearch-domain.Search
2019-08-18 03:52:40 Changing event name from docs.*.cloudsearchdomain.Search.complete-section to docs.*.cloudsearch-domain.Search.complete-section
2019-08-18 03:52:40 Changing event name from creating-client-class.iot-data to creating-client-class.iot-data-plane
2019-08-18 03:52:40 Changing event name from before-call.apigateway to before-call.api-gateway
2019-08-18 03:52:40 Changing event name from request-created.machinelearning.Predict to request-created.machine-learning.Predict
2019-08-18 03:52:40 Changing event name from before-parameter-build.autoscaling.CreateLaunchConfiguration to before-parameter-build.auto-scaling.CreateLaunchConfiguration
2019-08-18 03:52:40 Changing event name from before-parameter-build.route53 to before-parameter-build.route-53
2019-08-18 03:52:40 Changing event name from request-created.cloudsearchdomain.Search to request-created.cloudsearch-domain.Search
2019-08-18 03:52:40 Changing event name from docs.*.autoscaling.CreateLaunchConfiguration.complete-section to docs.*.auto-scaling.CreateLaunchConfiguration.complete-section
2019-08-18 03:52:40 Changing event name from before-parameter-build.logs.CreateExportTask to before-parameter-build.cloudwatch-logs.CreateExportTask
2019-08-18 03:52:40 Changing event name from docs.*.logs.CreateExportTask.complete-section to docs.*.cloudwatch-logs.CreateExportTask.complete-section
2019-08-18 03:52:40 Changing event name from before-parameter-build.cloudsearchdomain.Search to before-parameter-build.cloudsearch-domain.Search
2019-08-18 03:52:40 Changing event name from docs.*.cloudsearchdomain.Search.complete-section to docs.*.cloudsearch-domain.Search.complete-section
2019-08-18 03:52:40 local start-api command is called
2019-08-18 03:52:40 Looking for credentials via: env
2019-08-18 03:52:40 Looking for credentials via: assume-role
2019-08-18 03:52:40 Looking for credentials via: shared-credentials-file
2019-08-18 03:52:40 Found credentials in shared credentials file: ~/.aws/credentials
2019-08-18 03:52:40 Loading JSON file: D:\Program Files\Amazon\AWSSAMCLI\runtime\lib\site-packages\botocore\data\endpoints.json
2019-08-18 03:52:40 Event choose-service-name: calling handler <function handle_service_name_alias at 0x000001706550F620>
2019-08-18 03:52:40 Loading JSON file: D:\Program Files\Amazon\AWSSAMCLI\runtime\lib\site-packages\botocore\data\serverlessrepo\2017-09-08\service-2.json
2019-08-18 03:52:40 Event creating-client-class.serverlessapplicationrepository: calling handler <function add_generate_presigned_url at 0x00000170654CD8C8>
2019-08-18 03:52:40 The s3 config key is not a dictionary type, ignoring its value of: None
2019-08-18 03:52:40 Setting serverlessrepo timeout as (60, 60)
2019-08-18 03:52:40 Loading JSON file: D:\Program Files\Amazon\AWSSAMCLI\runtime\lib\site-packages\botocore\data\_retry.json
2019-08-18 03:52:40 Registering retry handlers for service: serverlessrepo
2019-08-18 03:52:40 No Parameters detected in the template
2019-08-18 03:52:40 2 resources found in the template
2019-08-18 03:52:40 Found Serverless function with name='HelloWorldFunction' and CodeUri='HelloWorldFunction'
2019-08-18 03:52:40 Trying paths: ['C:\\Users\\XXXX\\.docker\\config.json', 'C:\\Users\\XXXX\\.dockercfg']
2019-08-18 03:52:40 No config file found
2019-08-18 03:52:40 Trying paths: ['C:\\Users\\XXXX\\.docker\\config.json', 'C:\\Users\\XXXX\\.dockercfg']
2019-08-18 03:52:40 No config file found
2019-08-18 03:52:40 Starting new HTTPS connection (1): 192.168.99.100:2376
2019-08-18 03:52:40 https://192.168.99.100:2376 "GET /v1.35/_ping HTTP/1.1" 200 2
2019-08-18 03:52:40 Event choose-service-name: calling handler <function handle_service_name_alias at 0x000001706550F620>
2019-08-18 03:52:40 Event creating-client-class.serverlessapplicationrepository: calling handler <function add_generate_presigned_url at 0x00000170654CD8C8>
2019-08-18 03:52:40 The s3 config key is not a dictionary type, ignoring its value of: None
2019-08-18 03:52:40 Setting serverlessrepo timeout as (60, 60)
2019-08-18 03:52:40 Registering retry handlers for service: serverlessrepo
2019-08-18 03:52:40 No Parameters detected in the template
2019-08-18 03:52:40 2 resources found in the template
2019-08-18 03:52:40 Found '1' API Events in Serverless function with name 'HelloWorldFunction'
2019-08-18 03:52:40 Detected Inline Swagger definition
2019-08-18 03:52:40 Lambda function integration not found in Swagger document at path='/hello' method='get'
2019-08-18 03:52:40 Found '0' APIs in resource 'ServerlessRestApi'
2019-08-18 03:52:40 Removed duplicates from '0' Explicit APIs and '1' Implicit APIs to produce '1' APIs
2019-08-18 03:52:40 1 APIs found in the template
2019-08-18 03:52:40 Event choose-service-name: calling handler <function handle_service_name_alias at 0x000001706550F620>
2019-08-18 03:52:40 Loading JSON file: D:\Program Files\Amazon\AWSSAMCLI\runtime\lib\site-packages\botocore\data\lambda\2015-03-31\service-2.json
2019-08-18 03:52:40 Event creating-client-class.lambda: calling handler <function add_generate_presigned_url at 0x00000170654CD8C8>
2019-08-18 03:52:40 The s3 config key is not a dictionary type, ignoring its value of: None
2019-08-18 03:52:40 Setting lambda timeout as (60, 60)
2019-08-18 03:52:40 Registering retry handlers for service: lambda
2019-08-18 03:52:40 Trying paths: ['C:\\Users\\XXXX\\.docker\\config.json', 'C:\\Users\\XXXX\\.dockercfg']
2019-08-18 03:52:40 No config file found
2019-08-18 03:52:40 Trying paths: ['C:\\Users\\XXXX\\.docker\\config.json', 'C:\\Users\\XXXX\\.dockercfg']
2019-08-18 03:52:41 No config file found
2019-08-18 03:52:41 Mounting HelloWorldFunction at http://127.0.0.1:3000/hello [GET]
2019-08-18 03:52:41 You can now browse to the above endpoints to invoke your functions. You do not need to restart/reload SAM CLI while working on your functions changes will be reflected instantly/automatically. You only need to restart SAM CLI if you update your AWS SAM template
2019-08-18 03:52:41 Localhost server is starting up. Multi-threading = True
2019-08-18 03:52:41  * Running on http://127.0.0.1:3000/ (Press CTRL+C to quit)
2019-08-18 03:54:44 Constructed String representation of Event to invoke Lambda. Event: {"httpMethod": "GET", "body": null, "resource": "/hello", "requestContext": {"resourceId": "123456", "apiId": "1234567890", "resourcePath": "/hello", "httpMethod": "GET", "requestId": "c6af9ac6-7b61-11e6-9a41-93e8deadbeef", "accountId": "123456789012", "stage": "prod", "identity": {"apiKey": null, "userArn": null, "cognitoAuthenticationType": null, "caller": null, "userAgent": "Custom User Agent String", "user": null, "cognitoIdentityPoolId": null, "cognitoAuthenticationProvider": null, "sourceIp": "127.0.0.1", "accountId": null}, "extendedRequestId": null, "path": "/hello"}, "queryStringParameters": null, "headers": {"Host": "127.0.0.1:3000", "Connection": "keep-alive", "Cache-Control": "max-age=0", "Upgrade-Insecure-Requests": "1", "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.100 Safari/537.36", "Sec-Fetch-Mode": "navigate", "Sec-Fetch-User": "?1", "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3", "Sec-Fetch-Site": "none", "Accept-Encoding": "gzip, deflate, br", "Accept-Language": "en-US,en;q=0.9", "X-Forwarded-Proto": "http", "X-Forwarded-Port": "3000"}, "pathParameters": null, "stageVariables": null, "path": "/hello", "isBase64Encoded": false}
2019-08-18 03:55:06 Found one Lambda function with name 'HelloWorldFunction'
2019-08-18 03:55:06 Invoking app.lambda_handler (python3.6)
2019-08-18 03:55:06 Environment variables overrides data is standard format
2019-08-18 03:55:06 Loading AWS credentials from session with profile 'default'
2019-08-18 03:55:06 Resolving code path. Cwd=C:\Users\XXXX\sam-app\.aws-sam\build, CodeUri=HelloWorldFunction
2019-08-18 03:55:06 Resolved absolute path to code is C:\Users\XXXX\sam-app\.aws-sam\build\HelloWorldFunction
2019-08-18 03:55:06 Code C:\Users\XXXX\sam-app\.aws-sam\build\HelloWorldFunction is not a zip/jar file
2019-08-18 03:55:06 Skipping building an image since no layers were defined
2019-08-18 03:55:06 Trying paths: ['C:\\Users\\XXXX\\.docker\\config.json', 'C:\\Users\\XXXX\\.dockercfg']
2019-08-18 03:55:06 No config file found
2019-08-18 03:55:06 Trying paths: ['C:\\Users\\XXXX\\.docker\\config.json', 'C:\\Users\\XXXX\\.dockercfg']
2019-08-18 03:55:06 No config file found
2019-08-18 03:55:06 https://192.168.99.100:2376 "GET /v1.35/images/lambci/lambda:python3.6/json HTTP/1.1" 200 None
2019-08-18 03:55:06 Looking for auth config
2019-08-18 03:55:06 No auth config in memory - loading from filesystem
2019-08-18 03:55:06 Trying paths: ['C:\\Users\\XXXX\\.docker\\config.json', 'C:\\Users\\XXXX\\.dockercfg']
2019-08-18 03:55:06 No config file found
2019-08-18 03:55:06 Looking for auth entry for 'docker.io'
2019-08-18 03:55:06 No entry found
2019-08-18 03:55:06 No auth config found
2019-08-18 03:55:10 https://192.168.99.100:2376 "POST /v1.35/images/create?tag=python3.6&fromImage=lambci%2Flambda HTTP/1.1" 200 None

Fetching lambci/lambda:python3.6 Docker container image......
2019-08-18 03:55:10 Mounting C:\Users\XXXX\sam-app\.aws-sam\build\HelloWorldFunction as /var/task:ro inside runtime container
2019-08-18 03:55:10 Starting new HTTPS connection (1): 192.168.99.100:2376
2019-08-18 03:55:10 https://192.168.99.100:2376 "POST /v1.35/containers/create HTTP/1.1" 201 88
2019-08-18 03:55:10 https://192.168.99.100:2376 "GET /v1.35/containers/a157d80f0d79e848331551551f431b7efb5f70f0abcdd38c872ad0acc32e5c4d/json HTTP/1.1" 200 None
2019-08-18 03:55:10 https://192.168.99.100:2376 "GET /v1.35/containers/a157d80f0d79e848331551551f431b7efb5f70f0abcdd38c872ad0acc32e5c4d/json HTTP/1.1" 200 None
2019-08-18 03:55:11 https://192.168.99.100:2376 "POST /v1.35/containers/a157d80f0d79e848331551551f431b7efb5f70f0abcdd38c872ad0acc32e5c4d/start HTTP/1.1" 204 0
2019-08-18 03:55:11 Starting a timer for 3 seconds for function 'HelloWorldFunction'
2019-08-18 03:55:11 https://192.168.99.100:2376 "GET /v1.35/containers/a157d80f0d79e848331551551f431b7efb5f70f0abcdd38c872ad0acc32e5c4d/json HTTP/1.1" 200 None
2019-08-18 03:55:11 https://192.168.99.100:2376 "POST /containers/a157d80f0d79e848331551551f431b7efb5f70f0abcdd38c872ad0acc32e5c4d/attach?stdout=1&stderr=1&logs=1&stream=1&stdin=0 HTTP/1.1" 101 0
START RequestId: 806dd433-da87-4c33-a5d9-9953372d5a30 Version: $LATEST
Unable to import module 'app': No module named 'app'
END RequestId: 806dd433-da87-4c33-a5d9-9953372d5a30
REPORT RequestId: 806dd433-da87-4c33-a5d9-9953372d5a30 Duration: 1 ms Billed Duration: 100 ms Memory Size: 128 MB Max Memory Used: 19 MB
2019-08-18 03:55:11 Starting new HTTPS connection (2): 192.168.99.100:2376
2019-08-18 03:55:11 https://192.168.99.100:2376 "GET /v1.35/containers/a157d80f0d79e848331551551f431b7efb5f70f0abcdd38c872ad0acc32e5c4d/json HTTP/1.1" 200 None
2019-08-18 03:55:11 https://192.168.99.100:2376 "DELETE /v1.35/containers/a157d80f0d79e848331551551f431b7efb5f70f0abcdd38c872ad0acc32e5c4d?v=False&link=False&force=True HTTP/1.1" 204 0
2019-08-18 03:55:11 No Content-Type given. Defaulting to 'application/json'.
2019-08-18 03:55:11 127.0.0.1 - - [18/Aug/2019 03:55:11] "GET /hello HTTP/1.1" 200 -
2019-08-18 03:55:11 127.0.0.1 - - [18/Aug/2019 03:55:11] "GET /favicon.ico HTTP/1.1" 403 -

Expected result

In console, as per tutorial

 Fetching lambci/lambda:python3.6 Docker container image......
 2019-07-12 15:29:58 Mounting /<working-development-path>/sam-app/.aws-sam/build/HelloWorldFunction as /var/task:ro,delegated inside runtime container
 START RequestId: 52fdfc07-2182-154f-163f-5f0f9a621d72 Version: $LATEST
 END RequestId: 52fdfc07-2182-154f-163f-5f0f9a621d72
 REPORT RequestId: 52fdfc07-2182-154f-163f-5f0f9a621d72  Duration: 7.92 ms       Billed Duration: 100 ms Memory Size: 128 MB     Max Memory Used: 22 MB
 {"statusCode":200,"body":"{\"message\": \"hello world\"}"}

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

1. OS: Windows 10
2. sam --version: SAM CLI, version 0.10.0

Add --debug flag to command you are running

[sanathkr]

Have you shared the C:\ drive with Docker? This usually happens because the container mount failed.

[sidsamant]

I did share the drives but the mounts failed. Its a docker - VM issue as there are mount errors. Thanks for the tip.

[jpbelang]

I'm was having pretty much the same problem on MacOS using docker-toolbox.

Docker version 19.03.1, build 74b1e89
SAM CLI, version 0.21.0

The directories seemed to mount because they appeared in my virtualbox. However, the contents of the directory were empty.

I logged into my vm and hand mounted my home directory:

sudo mount -t vboxsf -o ro /Users /Users

And everything seemed to start working.

[sriram-mv]

Closing this issue as it looks be docker related mounting issues.

[srisaithilak]

I know this is old thread, but since I could not find much help online or understand what is explained in above thread, putting my two cents.
You have to create your project folder in C:\Users<username>...... so that docker toolbox has access to it. Else it will fail. Otherwise, you can follow the tutorial on http://support.divio.com/en/articles/646695-how-to-use-a-directory-outside-c-users-with-docker-toolbox-docker-for-windows to mount the project folder on the docker container.
Hope it helps.

[dominusmi]

To add to this, same thing on linux - if the code is in, for example, /tmp, it won't work. Needs to be in /home/{user}

[crwgregory]

I was having this same issue on macos.
I was able to get around it by adding the --not-cached flag to the aws build command.
sam build --no-cached

My use case is that I'm listening to changes to python and yaml files and rebuild the app on changes to have a "live reload" type of functionality. My make file is as such:

run:
	@sam build --no-cached
	sam local start-api --force-image-build

run-debug:
	@sam build --no-cached
	sam local start-api --debug

watch-build: # npm i -g nodemon    https://github.com/aws/aws-sam-cli/issues/921#issuecomment-613710539
	@nodemon -d 1 -e "py yaml" --exec sam build --no-cached

[OSIVZ]

Dear folks,

I read through this thread. There is a reference to the fact that on Linux (WSL falls into the detention) , a code must be in /home/{user} and in my case it is, yet the issue persists.
Running environment:
Windows 11, WSL 1
SAM CLI, version 1.97.0
Docker desktop version 4.21.1 (114176

The code is located in /home/{user}/sam-app

command:
sam local invoke HelloWorldFunction -e events/event.json --debug

2023-09-15 13:05:01,864 | Code /home/{user}/sam-app/.aws-sam/build/HelloWorldFunction is not a zip/jar file
2023-09-15 13:05:03,864 | Local image is up-to-date
2023-09-15 13:05:03,879 | Using local image: public.ecr.aws/lambda/python:3.10-rapid-x86_64.

2023-09-15 13:05:03,880 | Mounting /home/{user}/sam-app/.aws-sam/build/HelloWorldFunction as /var/task:ro,delegated, inside runtime container
2023-09-15 13:05:04,414 | Starting a timer for 3 seconds for function 'HelloWorldFunction'
START RequestId: e2fbc965-09e9-4b65-a6f5-663807520578 Version: $LATEST
Traceback (most recent call last): Unable to import module 'app': No module named 'app'
END RequestId: e2fbc965-09e9-4b65-a6f5-663807520578
REPORT RequestId: e2fbc965-09e9-4b65-a6f5-663807520578 Init Duration: 0.28 ms Duration: 79.13 ms Billed Duration: 80 ms Memory Size: 128 MB Max Memory Used: 128 MB
{"errorMessage": "Unable to import module 'app': No module named 'app'", "errorType": "Runtime.ImportModuleError", "requestId": "e2fbc965-09e9-4b65-a6f5-663807520578", "stackTrace": []}2023-09-15 13:05:05,953 | Cleaning all decompressed code dirs

Any suggestion?
Thank you