Role permission for invoking a lambda function"

Lambda Function A --> Lambda Function B

We have a lambda function A invokes another lambda function B. There was a permission error where we were getting AccessDeniedException: User is not authorized to perform lambda:InvokeFunction. We have added lambda:InvokeFunction to the role permission but it didn't fix the issue. Under Policies we had to add additional permissions to get this fixed.

Here is a part of SAM template with correct permission.

  - Statement:
      - Action:
          - lambda:Invoke
      - lambda:InvokeFunction
      - lambda:ListFunction
        Effect: Allow
    Resource: !GetAtt FunctionB