Cache the GHES instance check across organizations

enterprise? queried the meta endpoint on every call, and pending_members
calls it once per organization. Whether an instance is GHES cannot vary
between orgs on that instance, so this was one request per org for a
constant answer.

Caches against the address rather than the org signature. Checks for the
key rather than using ||= because false is a valid cached answer, and is
the answer github.com gives.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: d95a67cd-ec62-497a-99fc-cf447ee1d49b

Author: john7doe

lib/entitlements/service/github.rb

@@ -52,6 +52,7 @@ def initialize(addr: nil, org:, token:, ou:, ignore_not_found: false)
         # need to be obtained only one time per organization, but might be used multiple times.
         Entitlements.cache[:github_pending_members] ||= {}
         Entitlements.cache[:github_org_members] ||= {}
+        Entitlements.cache[:github_enterprise] ||= {}
       end
 
       # Return the identifier, either the address specified or otherwise "github.com".
@@ -97,13 +98,23 @@ def org_members
       end
 
       # Returns true if the github instance is an enterprise server instance
+      #
+      # Whether an instance is GHES is a property of the instance and not of any one organization,
+      # so this is cached against the address rather than the org signature. Without this the meta
+      # endpoint is queried once per organization, which is a request per org for an answer that
+      # cannot vary between them. Note this caches false as well as true, so it checks for the key
+      # rather than using ||=, since github.com correctly answers false here.
       Contract C::None => C::Bool
       def enterprise?
+        instance_signature = addr || ""
+        cache = Entitlements.cache[:github_enterprise]
+        return cache[instance_signature] if cache.key?(instance_signature)
+
         meta = Retryable.with_context(:default) do
           octokit.github_meta
         end
 
-        meta.key? :installed_version
+        cache[instance_signature] = meta.key?(:installed_version)
       end
 
       # Read the members of an organization who are in a "pending" role. These users should

spec/unit/entitlements/service/github_spec.rb

@@ -70,6 +70,28 @@
                   })
       expect(subject.enterprise?).to eq(true)
     end
+
+    it "queries the API only once per instance across multiple organizations" do
+      stub = stub_request(:get, "https://github.fake/api/v3/meta").
+        to_return({
+                    body: JSON.dump({ verifiable_password_authentication: true }),
+                    headers: {
+                      content_type: "application/json; charset=utf-8"
+                    }
+                  })
+
+      other_org = described_class.new(
+        addr: "https://github.fake/api/v3",
+        org: "puppiesinc",
+        token: "GoPackGo",
+        ou: "ou=puppiesinc,ou=GitHub,dc=github,dc=fake",
+        ignore_not_found: false
+      )
+
+      expect(subject.enterprise?).to eq(false)
+      expect(other_org.enterprise?).to eq(false)
+      expect(stub).to have_been_requested.once
+    end
   end
 
   describe "#pending_members" do