How do I specify template parameters when running AWS SAM Local?

Question

Using AWS SAM Local I can test my serverless application locally, which is awesome.

I can also deploy to AWS, which apparently takes the same flags as aws cloudformation deploy, so I can pass a parameters file with e.g. application secrets (API keys and such).

However, I can't find anything in aws local start-api --help or in the docs on Github about how to use a parameter file when testing locally.

How do I point to a parameters file to use with my template when running sam local start-api?

Answer 1

You can use the --parameter-overrides switch. The syntax is quite long winded, as below:

sam local start-api --parameter-overrides ParameterKey=Key1,ParameterValue=value1 ParameterKey=Key2,ParameterValue=value2

That is, you need to specify the key and value of each pair with comma separation.

And then each pair is separated with a space.

---

From sam local start-api --help:

  --parameter-overrides       Optional. A string that contains
                              CloudFormation parameter overrides encoded
                              as key=value pairs. Use the same format as
                              the AWS CLI, e.g. 'ParameterKey=KeyPairName,
                              ParameterValue=MyKey ParameterKey=InstanceTy
                              pe,ParameterValue=t1.micro'