This ensures the metrics proxy endpoint is ACL protected behind a
wildcard `service:read` and `node:read` set of rules. For Consul
Enterprise these will need to span all namespaces:
```
service_prefix "" { policy = "read" }
node_prefix "" { policy = "read" }
namespace_prefix "" {
service_prefix "" { policy = "read" }
node_prefix "" { policy = "read" }
}
```
This PR contains just the backend changes. The frontend changes to
actually pass the consul token header to the proxy through the JS plugin
will come in another PR.
* ACL Authorizer overhaul
To account for upcoming features every Authorization function can now take an extra *acl.EnterpriseAuthorizerContext. These are unused in OSS and will always be nil.
Additionally the acl package has received some thorough refactoring to enable all of the extra Consul Enterprise specific authorizations including moving sentinel enforcement into the stubbed structs. The Authorizer funcs now return an acl.EnforcementDecision instead of a boolean. This improves the overall interface as it makes multiple Authorizers easily chainable as they now indicate whether they had an authoritative decision or should use some other defaults. A ChainedAuthorizer was added to handle this Authorizer enforcement chain and will never itself return a non-authoritative decision.
* Include stub for extra enterprise rules in the global management policy
* Allow for an upgrade of the global-management policy
R.B. Boyer