fix: HAWNG-475 - Limits access to the cluster API using a whitelist

[phantomjinx]

• nginx-gateway.conf.template

  • Changes the master location to first send it through a javascript guard function that determines if the URI is acceptable. Thereby disallowing requests such as secrets and configmaps.

• nginx.js

  • proxyMasterGuard function that checks the given uri against a set of accepted patterns.
  • If pattern not found then return a 502 and error message.
  • If found then internally redirect to the masterinternal location

• test.js

  • Adds tests to check syntax and exercise proxyMasterGuard

[phantomjinx]

Trying to access the cluster secrets through the proxy API from external app returns a 502 error and a 'not allowed' message: