[Feature] completely separate stages #785

Prerequisites

• I am running the latest version. (up upgrade)
• I searched to see if the issue already exists.
• I inspected the verbose debug output with the -v, --verbose flag.
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Description

Essentially we need this

{
  "stages": {
    "staging": {
      "lambda": {
        "runtime": "nodejs10.x"
      }
    },
    "production": {
      "lambda": {
        "runtime": "nodejs8.10"
      }
    }
  }
}

Due to EOL of node 8 I upgraded several up deployments. nodejs10.x is the first runtime that runs on Amazon Linux 2.

This broke a deployment, because we had binaries that were compiled for Amazon Linux 1.

Now here's the feature request: Currently it's not possible to test a different runtime on staging while keeping production running as-is. It seems "lambda.runtime" is ignored inside the stages, at least the Version on the Lambda Dashboard doesn't change. This kind of makes sense because as far as I understand there's a Go proxy doing the "/production/" and "/staging/" routing inside the same runtime.

Assuming other runtimes (Python, Ruby, Java, Go, .NET) will eventually have versions running Amazon Linux 2 it would be really nice to be able to test in staging before changing production.

Edit: for anyone interested, this is related alixaxel/chrome-aws-lambda#37