Proxy pillar ID targetting

Issue

I was adding hundreds of proxy minion pillars for a cluster. During which, I realized that the proxy pillar format doesn't follow the regular pillar convention of descriptor-ID: key: value seen with regular pillars. This is a feature loss seeing as with regular pillars many can be listed in the same pillar sls file.

Instead, the "descriptor" is taken from the hard coded target ID in the /srv/pillar/top.sls file, with a proxy pillar file indent underneath. That pillar file contains a single pillar who's highest key is proxy:
This convention has the added loss of not being able to use wildcards * in the top file to break down minion targeting into groupings.

/srv/pillar/$ ls
net-device1.sls top.sls

/srv/pillar/$ cat top.sls
base:
  'target':
    - net-device1

/srv/pillar/$ cat net-device1.sls
proxy:
  proxytype: networkswitch
  host: 172.23.23.5
  username: root
  passwd: letmein

/srv/pillar/$ salt-proxy --proxyid=target -d 

This is unwieldy at scale, if I am adding hundreds of proxy pillars I'd prefer to segregate proxy pillars into files with a grouping convention rather than each proxy pillar getting its own file, and slot in the top.sls file.

Solution

Two part:

1. The salt-proxy --proxyid=[ID] targeting logic needs to be rewritten to allow the same minion ID targeting in the /srv/pillar/top.sls file as it is with /srv/salt/top.sls file for salt states.

2. Further the --proxyid should look for a proxy pillar indented key:value for its ID, or take it from the proxy pillar's descriptor-ID above proxy: like normal pillars.

/srv/pillar/$ ls
top.sls groupABC.sls group123.sls

/srv/pillar/$ cat top.sls
base:
  'switch*':
    - groupABC
  'router*':
    - group123

/srv/pillar/$ cat groupABC.sls
switch1:
  proxy:
    proxytype: networkswitch
    host: 172.23.23.5
    username: root
    passwd: letmein

switch2:
  proxy:
    proxytype: networkswitch
    host: 172.23.23.6
    username: root
    passwd: letmein

proxy:
  id: switch3
  proxytype: networkswitch
  host: 172.23.23.7
  username: root
  passwd: letmein

/srv/pillar/$ salt-proxy --proxyid=switch3 -d 
/srv/pillar/$ salt-proxy --proxyid=switch2 -d 

Please note that both proxy pillar structures would be valid for spinning up proxy switch2 & switch3 with this change.

Start by tracing the implementation behind salt-proxy --proxyid and how /srv/pillar/top.sls selects pillar files. Use the two YAML examples as behavioral requirements; done means proxy IDs can be targeted through grouped or wildcard top-file entries and both shown pillar structures are accepted.