SAM deploy doesn't set environment variables

Description

When using AWS SAM for local development, I can introduce environment variables by setting them in the template with no value, and then defining them in my environment. However, when I go to deploy, the environment variables do not appear to be inserted by sam package or sam deploy, and I get the following error on deploy:

Failed to create the changeset: Waiter ChangeSetCreateComplete failed: Waiter encountered a terminal failure state Status: FAILED. Reason: [/Resources/GeneratePlan/Type/Environment/Variables/SECRET_ACCESS_KEY] 'null' values are not allowed in templates

Where SECRET_ACCESS_KEY is one of my environment variables. I cannot find any documentation detailing how to deploy projects with environment variables, either by having them defined in my environment or providing them in an alternate config.

I don’t want to add the environment variables to my template.yml directly because this is stored in Git, and I don’t want to edit them manually into the packaged.yml file each time between the package and deploy steps as that’s cumbersome.

I haven’t seen any steps in the documentation or similar issues, so I presume this is either an edge case bug or I am just missing something simple (in which case I might file this as a documentation bug) 😄

Steps to reproduce

The following config is a minimal excerpt from mine:

AWSTemplateFormatVersion: '2010-09-09'

Transform: AWS::Serverless-2016-10-31

Globals:

  Function:
    Environment:
      Variables:
        SECRET_ACCESS_KEY:

Resources:

  AnswerChallenge:
    Type: "AWS::Serverless::Function"
    Properties:
      Runtime: nodejs8.10
      Handler: build/functions/answerChallenge.default
      CodeUri: ./
      Policies: AmazonDynamoDBFullAccess
      Events:
        GetRequest:
          Type: Api
          Properties:
            Path: /event
            Method: get

Observed result

When I run sam start-api with SECRET_ACCESS_KEY defined, the lambda works as expected. When I attempt to deploy with sam package and sam deploy, I receive an error about undefined variables.

Additional environment details (Ex: Windows, Mac, Amazon Linux etc)

1. OS: MacOS
2. sam --version: 0.11

[chrisfosterelli]

Yeah the sam local start-api also uses the mismatched format in --parameter-overrides, which is frustrating! Having to use two different config formats between local dev and prod deploy is not great… I had tried the --env-vars solution but had issues with the different cases expected between uppercase and snake case. This is what I had to do to get some resemblance of consistency:

I store my config file as a JSON file, such as config.json:

{
  "Region": "us-west-1",
  "Secret": "my-real-secret",
  [...]
}

And define them as parameters in the template.yaml:

Parameters:
  Secret:
    Type: String
  [...]

[... later ...]

Globals:
  Function:
    Environment:
      Variables:
        SECRET: !Ref Secret
        [...]

Then for development I have the following in package.json:

"scripts": {
  "api": "sam local start-api --region us-west-2 --parameter-overrides \"$(jq -r -j 'to_entries[] | \"ParameterKey=\\(.key),ParameterValue=\\(.value) \"' config.json)\"",
}

So I can run npm run api to get the api server going with the config file.

Then for deployment our CI runs:

> sam package --template-file ./template.yaml --s3-bucket bucketname --output-template-file ./packaged.yaml
> sam deploy --template-file ./packaged.yaml --stack-name stackname --capabilities CAPABILITY_IAM --parameter-overrides $(jq -r 'to_entries[] | "\(.key)=\(.value)"' config.json)

Surprising amount of work to get sane environment variables in SAM… I think this needs some developer experience TLC or maybe I’m missing something blatantly obvious 😅

[jsonmaur]

Same issue here. sam package/sam deploy should accept the --env-vars flag.

My current workaround is to use CF parameters, since sam package/sam deploy are aliases for cloudformation package/cloudformation deploy.

template.yml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Resources:
  SomeFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: some-function/
      Handler: index.handler
      Runtime: nodejs8.10
      Environment:
        Variables:
          SOME_VAR: !Ref SomeVar
Parameters:
  SomeVar:
    Type: String

$ sam package --template-file template.yml --s3-bucket BUCKET_NAME --output-template-file packaged.yml

$ sam deploy --template-file packaged.yml --stack-name STACK_NAME --capabilities CAPABILITY_IAM --parameter-overrides SomeVar=123