Default envvar value required to run?

[michaelwooley]

I'm seeing that I must provide a default value for environment variables in order for my commands to run.

In short:

${env:MY_ENV}      # FAILS

${evn:MY_ENV, ''}  # OK

Command results

Without default environment variable value

If I run without a default value (i.e. ${env:MY_ENV}) I get:

❯ serverless package
Running "serverless" from node_modules
Environment: linux, node 16.16.0, framework 3.36.0 (local) 3.36.0v (global), plugin 7.1.0, SDK 4.4.0
Docs:        docs.serverless.com
Support:     forum.serverless.com
Bugs:        github.com/serverless/serverless/issues

Error:
Cannot resolve serverless.yml: Variables resolution errored with:
  - Cannot resolve variable at "provider.environment.MY_ENV": Value not found at "env" source

With default environment variable value

If I add a default value (i.e. ${env:MY_ENV, ''}) I get:

❯ serverless package
Running "serverless" from node_modules
DOTENV: Loading environment variables from .env:
         - MY_ENV

Packaging aws-python-http-api-project for stage dev (us-east-1)

Example serverless.yaml file

(Modified version of the boilerplate project. Similar to serverless/examples/aws-python-http-api.)

service: aws-python-http-api-project

provider:
  name: aws
  runtime: python3.9
  environment:
    MY_ENV: ${env:MY_ENV, ''} # Must include default!

functions:
  hello:
    handler: handler.hello
    events:
      - httpApi:
          path: /
          method: get

plugins:
  - serverless-dotenv-plugin

custom:
  dotenv:
    logging: true

Version info

❯ sls --version
Running "serverless" from node_modules
Framework Core: 3.36.0 (local) 3.36.0 (global)
Plugin: 7.1.0
SDK: 4.4.0