Add description about common configuration file and environment variables

[yumaoka]

GP SDKs and tools should support common configuration file (JSON file which store credentials and options) and/or environment variables. We should have a page explaining these configuration file/variables in this repository, so GP SDKs/tools can link to the page.

[srl295]

format for gp-config.json -

{
 "credentials": { … } 
}

[srl295]

Perhaps mention that cf csk and related could be used from the command line to work with credentials.

cf csk mygp mykey
cf service-key mygp mykey | tail +2 > creds.json

[srl295]

also the credentials url should end in /rest per IBM-Cloud/gp-js-client#33

[yumaoka]

Bluemix console "Credentials" tab for a service shows -

{
  "url": "https://gp-rest.ng.bluemix.net/translate/rest",
  "userId": "2ba50aeb88e61a371c9906e569a950f3",
  "password": "3UTlbuS/igbWn1MshQ66GEn4LNMIMDw2",
  "instanceId": "49c520f1208e6c27388e9ac4ec0358ec"
}

Connections - view credentials in App page shows -

{
  "gp-test": [
    {
      "credentials": {
        "url": "https://gp-rest.ng.bluemix.net/translate/rest",
        "userId": "c5bd4c4a6c578f9c835fa57b7981915d",
        "password": "ImhQN0xKIGZCaRDpA/b3QLY62akqzKjz",
        "instanceId": "1581368afcb8e40c0b10f889f3a32662"
      },
      "syslog_drain_url": null,
      "label": "gp-test",
      "provider": null,
      "plan": "standard",
      "name": "yoshito-gp-test",
      "tags": [
        "dev_ops",
        "ibm_created",
        "ibm_dedicated_public",
        "ibm_release"
      ]
    }
  ]
}

My preference is to use the first one as the primary format when credentials are provided in a JSON format for client SDK and tools.