Add support for deploying to multiple stages

[leftclickben]

Currently if deploying first to the default stage (as specified in the provider settings or by default) with sls deploy and then deploying to a different stage, e.g. sls deploy --stage production, an error occurs:

An error occurred while provisioning your stack: IamRoleApiGatewayCloudwatchLogRole
- project-name-ap-southeast-2-apiGatewayLogRole
already exists in stack arn:aws:cloudformation:ap-southeast-2:012345678910:stack/project-name-staging/41741b71-352e-11e7-b4ff-50fae94facba.

[leftclickben]

Complete output of second deployment, with -v option:

Serverless: Packaging service...
Serverless: Commencing API Gateway stage configuration
Serverless: API Gateway stage configuration complete
Serverless: Uploading CloudFormation file to S3...
Serverless: Uploading service .zip file to S3 (25.52 MB)...
Serverless: Updating Stack...
Serverless: Checking Stack update progress...
CloudFormation - UPDATE_IN_PROGRESS - AWS::CloudFormation::Stack - project-name
CloudFormation - CREATE_IN_PROGRESS - AWS::ApiGateway::RestApi - ApiGatewayRestApi
CloudFormation - CREATE_IN_PROGRESS - AWS::Logs::LogGroup - UpdateLogGroup
CloudFormation - CREATE_IN_PROGRESS - AWS::SQS::Queue - PrerenderQueue
CloudFormation - CREATE_IN_PROGRESS - AWS::Logs::LogGroup - LastUpdatedLogGroup
CloudFormation - CREATE_IN_PROGRESS - AWS::S3::Bucket - TargetBucket
CloudFormation - CREATE_IN_PROGRESS - AWS::Logs::LogGroup - GenerateLogGroup
CloudFormation - CREATE_IN_PROGRESS - AWS::Logs::LogGroup - PrerenderLogGroup
CloudFormation - CREATE_IN_PROGRESS - AWS::ApiGateway::RestApi - ApiGatewayRestApi
CloudFormation - CREATE_IN_PROGRESS - AWS::IAM::Role - IamRoleApiGatewayCloudwatchLogRole
CloudFormation - CREATE_COMPLETE - AWS::ApiGateway::RestApi - ApiGatewayRestApi
CloudFormation - CREATE_IN_PROGRESS - AWS::Logs::LogGroup - UpdateLogGroup
CloudFormation - CREATE_IN_PROGRESS - AWS::SQS::Queue - PrerenderQueue
CloudFormation - CREATE_IN_PROGRESS - AWS::Logs::LogGroup - LastUpdatedLogGroup
CloudFormation - CREATE_COMPLETE - AWS::SQS::Queue - PrerenderQueue
CloudFormation - CREATE_COMPLETE - AWS::Logs::LogGroup - LastUpdatedLogGroup
CloudFormation - CREATE_IN_PROGRESS - AWS::Logs::LogGroup - PrerenderLogGroup
CloudFormation - CREATE_IN_PROGRESS - AWS::Logs::LogGroup - GenerateLogGroup
CloudFormation - CREATE_FAILED - AWS::IAM::Role - IamRoleApiGatewayCloudwatchLogRole
CloudFormation - CREATE_COMPLETE - AWS::Logs::LogGroup - UpdateLogGroup
CloudFormation - CREATE_COMPLETE - AWS::Logs::LogGroup - GenerateLogGroup
CloudFormation - CREATE_COMPLETE - AWS::Logs::LogGroup - PrerenderLogGroup
CloudFormation - CREATE_FAILED - AWS::S3::Bucket - TargetBucket
CloudFormation - UPDATE_ROLLBACK_IN_PROGRESS - AWS::CloudFormation::Stack - project-name-production
CloudFormation - UPDATE_ROLLBACK_COMPLETE_CLEANUP_IN_PROGRESS - AWS::CloudFormation::Stack - project-name-production
CloudFormation - DELETE_IN_PROGRESS - AWS::Logs::LogGroup - PrerenderLogGroup
CloudFormation - DELETE_IN_PROGRESS - AWS::ApiGateway::RestApi - ApiGatewayRestApi
CloudFormation - DELETE_IN_PROGRESS - AWS::Logs::LogGroup - UpdateLogGroup
CloudFormation - DELETE_IN_PROGRESS - AWS::SQS::Queue - PrerenderQueue
CloudFormation - DELETE_COMPLETE - AWS::IAM::Role - IamRoleApiGatewayCloudwatchLogRole
CloudFormation - DELETE_IN_PROGRESS - AWS::Logs::LogGroup - GenerateLogGroup
CloudFormation - DELETE_IN_PROGRESS - AWS::Logs::LogGroup - LastUpdatedLogGroup
CloudFormation - DELETE_IN_PROGRESS - AWS::S3::Bucket - TargetBucket
CloudFormation - DELETE_COMPLETE - AWS::Logs::LogGroup - PrerenderLogGroup
CloudFormation - DELETE_COMPLETE - AWS::ApiGateway::RestApi - ApiGatewayRestApi
CloudFormation - DELETE_COMPLETE - AWS::Logs::LogGroup - UpdateLogGroup
CloudFormation - DELETE_COMPLETE - AWS::Logs::LogGroup - GenerateLogGroup
CloudFormation - DELETE_COMPLETE - AWS::Logs::LogGroup - LastUpdatedLogGroup
CloudFormation - DELETE_COMPLETE - AWS::S3::Bucket - TargetBucket
CloudFormation - DELETE_COMPLETE - AWS::SQS::Queue - PrerenderQueue
CloudFormation - UPDATE_ROLLBACK_COMPLETE - AWS::CloudFormation::Stack - project-name-production
Serverless: Deployment failed!
 
  Serverless Error ---------------------------------------
 
     An error occurred while provisioning your stack: IamRoleApiGatewayCloudwatchLogRole
     - project-name-ap-southeast-2-apiGatewayLogRole
     already exists in stack arn:aws:cloudformation:ap-southeast-2:012345678910:stack/project-name-staging/41741b71-352e-11e7-b4ff-50fae94facba.
 
  Get Support --------------------------------------------
     Docs:          docs.serverless.com
     Bugs:          github.com/serverless/serverless/issues
 
  Your Environment Information -----------------------------
     OS:                 linux
     Node Version:       7.7.2
     Serverless Version: 1.8.0

[lucasklaassen]

I've been searching through serverless AWS plugins to find one that supports multiple stages. Currently working through an issue on this plugin: https://github.com/amplify-education/serverless-vpc-discovery/issues/4

I will update you if I find a plugin that has support added for it. Maybe we can get a pull request up for both plugins!

The biggest issue I'm running into is how to evaluate custom variables within the serverless.yml config that gets pulled in.