AWS Lambda - 无法导入模块“main”：没有名为“psycopg2”的模块

Question

I'm trying to run my script on my local machine using this command sam local invoke MyFunction but I got this error message.

Invoking main.lambda_handler (python3.8)
Skip pulling image and use local one: amazon/aws-sam-cli-emulation-image-python3.8:rapid-1.22.0.
START RequestId: 56f2ad8a-ff9b-49cb-87f0-fda8723627ac Version: $LATEST
Traceback (most recent call last): Unable to import module 'main': No module named 'psycopg2'
END RequestId: 56f2ad8a-ff9b-49cb-87f0-fda8723627ac
REPORT RequestId: 56f2ad8a-ff9b-49cb-87f0-fda8723627ac  Init Duration: 0.23 ms Duration: 91.34 ms                                                   Billed Duration: 100 ms  Memory Size: 128 MB     Max Memory Used: 128 MB        
{"errorMessage": "Unable to import module 'main': No module named 'psycopg2'", "errorType": "Runtime.ImportModuleError", "stackTrace": []}

I already cpied and put the library into the AWS Lambda project folder.

Answer 1

You need to copy the psycopg2 library in Lambda project folder under .aws-sam/build directory.

Although, the best way would be to provide requirements.txt file in your lambda project folder and mention your dependencies in there. Then the sam build command will download and copy the dependencies in .aws-sam/build directory for you.

Without the entry in requirements.txt file, you will loose manually copied files uder .aws-sam/build directory on running subsequent sam build command.