add support for lambda env vars in invoke local

[eahefnawy]

What did you implement:

Add support for lambda env vars in invoke local. Any env vars that you set in serverless.yml will be available when you run sls invoke local without having to load them manually.

How did you implement it:

Added a new loadEnvVars() method to invoke local that runs before running the function.

How can we verify it:

serverless.yml

service: serverless-local-env-vars

provider:
  name: aws
  cfLogs: true
  environment:
    hello: world

functions:
  hello:
    environment:
      hello2: world2
      hello: worldOverwritten
    handler: handler.hello

handler.js:

module.exports.hello = (event, context, callback) => {
  console.log(process.env.hello)
  console.log(process.env.hello2)
  const body = {
    message: 'Go Serverless v1.0! Your function executed successfully!',
    input: event,
  };

  const response = {
    statusCode: 200,
    headers: {
      'custom-header': 'Custom header value',
    },
    body: JSON.stringify(event),
  };

  return  callback(null, event);
};

run serverless invoke local -f hello and see the env vars values in the console

Todos:

• Write tests
• Write documentation
• Fix linting errors
• Make sure code coverage hasn't dropped
• Provide verification config/commands/resources
• Enable "Allow edits from maintainers" for this PR
• Change ready for review message below

Is this ready for review?: YES

[nikgraf]

Reviewing now …

[nikgraf]

@eahefnawy just tested it with new examples and works like a charm

[jeremydaly]

I have ARNs from Cloudformation outputs populating my environment variables in my Serverless.yml config. Running invoke local loads the environment variable, but populates it with the static JSON instead of the correct output.

  environment:
    NOTIFICATION_TOPIC: { "Ref": "notifications" }

[pmuens]

@jeremydaly thanks for reporting 👍

Could you open up a new issue for that?

/cc @eahefnawy

[mrowles]

Lovely work :)