Extract EachShardWorker into a concern

app/workers/concerns/each_shard_worker.rb

+module EachShardWorker
+  extend ActiveSupport::Concern
+  include ::Gitlab::Utils::StrongMemoize
+
+  HEALTHY_SHARD_CHECKS = [
+    Gitlab::HealthChecks::GitalyCheck
+  ].freeze
+
+  def each_shard
+    eligible_shard_names.each do |shard_name|
+      yield shard_name
+    end
+  end
+
+  # override when you want to filter out some shards
+  def eligible_shard_names
+    healthy_shard_names
+  end
+
+  def healthy_shard_names
+    strong_memoize(:healthy_shard_names) do
+      # For now, we need to perform both Gitaly and direct filesystem checks to ensure
+      # the shard is healthy. We take the intersection of the successful checks
+      # as the healthy shards.
+      healthy_ready_shards.map { |result| result.labels[:shard] }.compact.uniq
+    end
+  end
+
+  def healthy_ready_shards
+    ready_shards.map { |result| result.select(&:success) }.inject(:&)
+  end
+
+  def ready_shards
+    HEALTHY_SHARD_CHECKS.map(&:readiness)
+  end
+end

ee/app/workers/geo/scheduler/per_shard_scheduler_worker.rb

@@ -3,43 +3,18 @@ module Geo
     class PerShardSchedulerWorker
       include ApplicationWorker
       include CronjobQueue
-      include ::Gitlab::Utils::StrongMemoize
       include ::Gitlab::Geo::LogHelpers
-
-      HEALTHY_SHARD_CHECKS = [
-        Gitlab::HealthChecks::GitalyCheck
-      ].freeze
+      include ::EachShardWorker
 
       def perform
         Gitlab::Geo::ShardHealthCache.update(eligible_shard_names)
 
-        eligible_shard_names.each { |shard_name| schedule_job(shard_name) }
-      end
-
-      def eligible_shard_names
-        healthy_shard_names
+        each_shard { |shard_name| schedule_job(shard_name) }
       end
 
       def schedule_job(shard_name)
         raise NotImplementedError
       end
-
-      def healthy_shard_names
-        strong_memoize(:healthy_shard_names) do
-          # For now, we need to perform both Gitaly and direct filesystem checks to ensure
-          # the shard is healthy. We take the intersection of the successful checks
-          # as the healthy shards.
-          healthy_ready_shards.map { |result| result.labels[:shard] }.compact.uniq
-        end
-      end
-
-      def ready_shards
-        HEALTHY_SHARD_CHECKS.map(&:readiness)
-      end
-
-      def healthy_ready_shards
-        ready_shards.map { |result| result.select(&:success) }.inject(:&)
-      end
     end
   end
 end

ee/spec/workers/geo/scheduler/per_shard_scheduler_worker_spec.rb

@@ -17,12 +17,6 @@ describe Geo::Scheduler::PerShardSchedulerWorker do
     expect(described_class).to include_module(::Gitlab::Geo::LogHelpers)
   end
 
-  it 'includes Gitaly health checks' do
-    expect(described_class::HEALTHY_SHARD_CHECKS).to include(
-      Gitlab::HealthChecks::GitalyCheck
-    )
-  end
-
   describe 'instance methods' do
     subject(:per_shard_scheduler_worker) { described_class.new }
 
@@ -47,7 +41,7 @@ describe Geo::Scheduler::PerShardSchedulerWorker do
     end
 
     describe '#ready_shards' do
-      let(:ready_shards) { [[default_shard, other_shard, unhealthy_shard]] }
+      let(:ready_shards) { [default_shard, other_shard, unhealthy_shard] }
 
       it "returns an array of ready shards" do
         expect(per_shard_scheduler_worker.ready_shards).to eq(ready_shards)