Broker does not log nor panic on listener setup errors

[sgnn7]

Our connectors do not exit when there’s a problem with them starting and on top of it, on some errors we don’t log what the problem is.

Example problematic config (though others can apply fine):

version: 2
services:
  some-connector:
    connector: generic_http
    listenOn: tcp://0.0.0.0:8080
    credentials:
      jwtToken:
        from: literal
        get: some-value
    config:
      headers:
        ClientID: "12345678"
        ClientSecret: "{{ .jwtToken }}"
      forceSSL: true
      match:
        - ^http

AC:

• Add fatal exit on any connector errors
• Log all startup errors

[sgnn7]

CC: @izgeri

[sgnn7]

Draft PR that may need tests for it: #1059

[sgnn7]

CR ready: #1059

[izgeri]

This was released in v1.4.2

Note that before this change was released, if you ran Secretless with the config above Secretless would hang on startup at the following line:

2020/01/09 13:42:54 Secretless v1.4.1-dev starting up...
2020/01/09 13:42:54 Initializing health check on :5335...
2020/01/09 13:42:54 Initialization of health check done. You can access the endpoint at `/live` and `/ready`.
2020/01/09 13:42:54 [WARN]  Plugin hashes were not provided - tampering will not be detectable!
2020/01/09 13:42:54 Trying to load configuration file: ../secretless-other/test.yml
2020/01/09 13:42:54 Registering reload signal listeners...

with these changes, however, Secretless dies and shares an error message related to the problem:

2020/01/09 13:54:19 Secretless v1.4.2-dev starting up...
2020/01/09 13:54:19 Initializing health check on :5335...
2020/01/09 13:54:19 Initialization of health check done. You can access the endpoint at `/live` and `/ready`.
2020/01/09 13:54:19 [WARN]  Plugin hashes were not provided - tampering will not be detectable!
2020/01/09 13:54:19 Trying to load configuration file: ../secretless-other/test.yml
2020/01/09 13:54:19 Registering reload signal listeners...
2020/01/09 13:54:19 [WARN]  Starting HTTP listener on 0.0.0.0:8080...
2020/01/09 13:54:19 [ERROR] configuration parsing of 'generic_http' failed: 'authenticateURLsMatching' key has incorrect type, must be a string or list of strings
2020/01/09 13:54:19 [ERROR] Fatal error in 'HTTP Proxy on tcp://0.0.0.0:8080': unable to create HTTP proxy service on 'tcp://0.0.0.0:8080': 'authenticateURLsMatching' key has incorrect type, must be a string or list of strings