Refactor GCP session token exchange scheme

app/controllers/projects/clusters/gcp_controller.rb

@@ -65,11 +65,7 @@ class Projects::Clusters::GcpController < Projects::ApplicationController
   end
   def authorize_google_project_billing
-    redis_token_key = CheckGcpProjectBillingWorker.generate_redis_token_key
-    Gitlab::Redis::SharedState.with do |redis|
-      redis.set(redis_token_key, token_in_session, ex: 5.minutes)
-    end
-
+    redis_token_key = CheckGcpProjectBillingWorker.store_session_token(token_in_session)
     CheckGcpProjectBillingWorker.perform_async(redis_token_key)
   end

app/workers/check_gcp_project_billing_worker.rb

@@ -5,9 +5,20 @@ class CheckGcpProjectBillingWorker
   include ClusterQueue
   LEASE_TIMEOUT = 15.seconds.to_i
-  def self.generate_redis_token_key
-    SecureRandom.uuid
+  SESSION_KEY_TIMEOUT = 5.minutes
+  def self.get_session_token(token_key)
+    Gitlab::Redis::SharedState.with do |redis|
+      redis.get(get_redis_session_key(token_key))
+    end
+  end
+
+  def self.store_session_token(token)
+    generate_token_key.tap do |token_key|
+      Gitlab::Redis::SharedState.with do |redis|
+        redis.set(get_redis_session_key(token_key), token, ex: SESSION_KEY_TIMEOUT)
+      end
+    end
   end
   def self.redis_shared_state_key_for(token)
@@ -17,7 +28,7 @@ class CheckGcpProjectBillingWorker
   def perform(token_key)
     return unless token_key
-    token = get_token(token_key)
+    token = self.get_session_token(token_key)
     return unless token
     return unless try_obtain_lease_for(token)
@@ -29,8 +40,12 @@ class CheckGcpProjectBillingWorker
   private
-  def get_token(token_key)
-    Gitlab::Redis::SharedState.with { |redis| redis.get(token_key) }
+  def self.generate_token_key
+    SecureRandom.uuid
+  end
+
+  def self.get_redis_session_key(token_key)
+    "gitlab:gcp:session:#{token_key}"
   end
   def try_obtain_lease_for(token)

spec/workers/check_gcp_project_billing_worker_spec.rb

@@ -8,7 +8,7 @@ describe CheckGcpProjectBillingWorker do
     context 'when there is a token in redis' do
       before do
-        allow_any_instance_of(described_class).to receive(:get_token).and_return(token)
+        allow_any_instance_of(described_class).to receive(:get_session_token).and_return(token)
       end
       context 'when there is no lease' do
@@ -48,7 +48,7 @@ describe CheckGcpProjectBillingWorker do
     context 'when there is no token in redis' do
       before do
-        allow_any_instance_of(described_class).to receive(:get_token).and_return(nil)
+        allow_any_instance_of(described_class).to receive(:get_session_token).and_return(nil)
       end
       it 'does not call the service' do