Serverless Framework - useDotenv is not loading env file in AWS

Question

I'm using the useDotenv property on my serverless.yml but it is not loading in AWS:

org: xyz
app: route-learner
service: route-learner-cron
frameworkVersion: '3'

useDotenv: true

provider:
  name: aws
  runtime: python3.8
  stage: ${opt:stage, 'dev'}

functions:
  extract_route:
    handler: src.functions.extract_route.run
    events:
      # Invoke Lambda function at every 5th minute.
      - schedule:
          rate: cron(5,15,25,35,45,55 * * * ? *)
    vpc:
      securityGroupIds:
        - ...
      subnetIds:
        - ...

plugins:
  - serverless-python-requirements

custom:
  pythonRequirements:
    dockerizePip: true

I have in the root directory a.env.prod file with the following:

DB_URI=my_db_url
DB_VERBOSE=True

I'm deploying the function with the command:

serverless deploy --stage prod --verbose

Once the function is called, I see the following error:

[ERROR] KeyError: 'DB_URI'
Traceback (most recent call last):
  File "/var/task/serverless_sdk/__init__.py", line 144, in wrapped_handler
    return user_handler(event, context)
  File "/var/task/s_extract_route.py", line 25, in error_handler
    raise e
  File "/var/task/s_extract_route.py", line 20, in <module>
    user_handler = serverless_sdk.get_user_handler('src.functions.extract_route.run')
  File "/var/task/serverless_sdk/__init__.py", line 56, in get_user_handler
    user_module = import_module(user_module_name)
  File "/var/lang/lib/python3.8/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 961, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 843, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/var/task/src/functions/__init__.py", line 8, in <module>
    from src.db import engine
  File "/var/task/src/db.py", line 4, in <module>
    DATABASE_URI = os.environ['DB_URI']
  File "/var/lang/lib/python3.8/os.py", line 675, in __getitem__
    raise KeyError(key) from None
[ERROR] KeyError: 'DB_URI' Traceback (most recent call last):   File "/var/task/serverless_sdk/__init__.py", line 144, in wrapped_handler     return user_handler(event, context)   File "/var/task/s_extract_route.py", line 25, in error_handler     raise e   File "/var/task/s_extract_route.py", line 20, in <module>     user_handler = serverless_sdk.get_user_handler('src.functions.extract_route.run')   File "/var/task/serverless_sdk/__init__.py", line 56, in get_user_handler     user_module = import_module(user_module_name)   File "/var/lang/lib/python3.8/importlib/__init__.py", line 127, in import_module     return _bootstrap._gcd_import(name[level:], package, level)   File "<frozen importlib._bootstrap>", line 1014, in _gcd_import   File "<frozen importlib._bootstrap>", line 991, in _find_and_load   File "<frozen importlib._bootstrap>", line 961, in _find_and_load_unlocked   File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed   File "<frozen importlib._bootstrap>", line 1014, in _gcd_import   File "<frozen importlib._bootstrap>", line 991, in _find_and_load   File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked   File "<frozen importlib._bootstrap>", line 671, in _load_unlocked   File "<frozen importlib._bootstrap_external>", line 843, in exec_module   File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed   File "/var/task/src/functions/__init__.py", line 8, in <module>     from src.db import engine   File "/var/task/src/db.py", line 4, in <module>     DATABASE_URI = os.environ['DB_URI']   File "/var/lang/lib/python3.8/os.py", line 675, in __getitem__     raise KeyError(key) from None

What is missing in my serverless configuration?

Answer 1

I have found the issue, the useDotenv attribute simply includes the content of .env file to the serverless.yml file. So, I still need to declare the environment variable inside the template:

environment:
    DB_URI: ${env:DB_URI}
    DB_VERBOSE: ${env:DB_VERBOSE}

The .env file is not included in the final package deployed to AWS.