Disable mirror workers for Geo secondaries

Customers using remote mirrors would see errors in their Sidekiq logs after
the worker attempted to update its database.  We should disable this until we
have a better way of synching the mirror workers.

See #1598

app/models/remote_mirror.rb

@@ -75,6 +75,7 @@ class RemoteMirror < ActiveRecord::Base
 
   def sync
     return unless project && enabled
+    return if Gitlab::Geo.secondary?
 
     RepositoryUpdateRemoteMirrorWorker.perform_in(BACKOFF_DELAY, self.id, Time.now) if project&.repository_exists?
   end

app/workers/update_all_mirrors_worker.rb

@@ -5,6 +5,9 @@ class UpdateAllMirrorsWorker
   LEASE_TIMEOUT = 840
 
   def perform
+    # This worker requires updating the database state, which we can't
+    # do on a Geo secondary
+    return if Gitlab::Geo.secondary?
     return unless try_obtain_lease
 
     fail_stuck_mirrors!

changelogs/unreleased-ee/sh-test.yml

+---
+title: Disable mirror workers for Geo secondaries
+merge_request:
+author:

lib/gitlab/mirror.rb

@@ -41,11 +41,23 @@ module Gitlab
         sync_times
       end
 
+      def update_all_mirrors_cron_job
+        Sidekiq::Cron::Job.find("update_all_mirrors_worker")
+      end
+
+      def destroy_cron_job!
+        update_all_mirrors_cron_job&.destroy
+      end
+
       def configure_cron_job!
+        if Gitlab::Geo.secondary?
+          destroy_cron_job!
+          return
+        end
+
         minimum_mirror_sync_time = current_application_settings.minimum_mirror_sync_time rescue FIFTEEN
         sync_time = SYNC_TIME_TO_CRON[minimum_mirror_sync_time]
-
-        Sidekiq::Cron::Job.find("update_all_mirrors_worker")&.destroy
+        destroy_cron_job!
 
         Sidekiq::Cron::Job.create(
           name: 'update_all_mirrors_worker',

spec/lib/gitlab/mirror_spec.rb

@@ -191,6 +191,19 @@ describe Gitlab::Mirror do
           expect(Sidekiq::Cron::Job.find("update_all_mirrors_worker").cron).to eq(fifteen_cron)
         end
       end
+
+      describe 'when Geo is enabled' do
+        it 'disables mirror cron job' do
+          described_class.configure_cron_job!
+
+          expect(described_class.update_all_mirrors_cron_job).to be_enabled
+
+          allow(Gitlab::Geo).to receive(:secondary?).and_return(true)
+          described_class.configure_cron_job!
+
+          expect(described_class.update_all_mirrors_cron_job).to be_nil
+        end
+      end
     end
   end
 

spec/models/remote_mirror_spec.rb

@@ -115,6 +115,14 @@ describe RemoteMirror do
         expect(remote_mirror.sync).to be_nil
       end
     end
+
+    context 'as a Geo secondary' do
+      it 'returns nil' do
+        allow(Gitlab::Geo).to receive(:secondary?).and_return(true)
+
+        expect(remote_mirror.sync).to be_nil
+      end
+    end
   end
 
   context '#updated_since?' do