Add support for --profile for selecting IAM credentials

[doIIarplus]

Related Issue: #27

Adds --profile as a new flag for start-api and invoke to allow user to specify specific profiles if needed, instead of always using the default profile

[resios]

Why not set the AWS_PROFILE environment variable as instructed by: http://docs.aws.amazon.com/sdk-for-java/v1/developer-guide/credentials.html#credentials-default

This way no change to aws-sam-local is required.

[sanathkr]

--profile is also the standard AWS CLI way of specifying profile. Tools other than AWS CLI that source creds have generally exposed this flag to customers in addition to AWS_PROFILE. It is a good to have

[sanathkr]

Notes for future: common options like profile must be abstracted into an args object and passed down to Invoke/StartApi for processing.

[sanathkr]

Thanks for doing it!

[cam8001]

Is this flag in the current version of sam-cli? It doesn't seem to show up in 0.15 from Brew:

$ sam --version                                                                                                                                                                
SAM CLI, version 0.15.0

$ sam --profile datalake                                                                                                                                                        
Error: no such option: --profile

[Zanndorin]

@cam8001 It is but at the end of the command
sam local start-api --profile devAdmin

https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/sam-cli-command-reference-sam-local-invoke.html