Feature: generate public/private key-pair for use with queue-worker callbacks

[alexellis]

Expected Behaviour

Installation process for OpenFaaS should generate private / public key-pair that can be used by the system for non-repudiation of async function invocation during the callback phase

Tasks

General

• Pick up old PRs rebase and re-test whole solution
• Agree on definition of done for the feature. @alexellis any other tasks you see missing here?

Installation

• Kubernetes Yaml installation. PR Enable non-repudiation for function callbacks faas-netes#389
• Kubernetes Helm installation. PR Enable non-repudiation for function callbacks faas-netes#389
• Swarm installation via deploy_stack.sh. PR http signatures: add support for RSA message signing #1101

Functionality

• Gateway expose system end-point to read public key. PR http signatures: add support for RSA message signing #1101
• Message signing in queue worker. Adds http signatures to callbacks nats-queue-worker#56

Testing

• Instruction on how to test the entire feature. Adds http signatures to callbacks nats-queue-worker#56

Documentation

• Document how to use this feature in swarm, kubernetes yaml and helm.

PR merge order

• Gatway changes
• Queue worker
• Documentation

Design

Below is the conceptual flow showing how this works:

[ewilde]

Derek assign: ewilde

[alexellis]

I think this should cover the connector-sdk too, which invokes functions in almost the same way as the queue worker.