add ?flakey=pct param to make the app return 500 errors intermittently

app.rb

@@ -23,6 +23,7 @@ require "config"
 CHUNK_SIZE = 1024**2
 SESSION_SECRET_HEX_LENGTH = 64
 JWT_SECRET_HEX_LENGTH = 64
+DEFAULT_FLAKEY = 50
 
 ENV_PREFIX = "KUBERNAUT"
 
@@ -207,6 +208,13 @@ Health.instance.up
 Ready.instance.up
 Sleep.instance.wake
 
+def flaky(pct = DEFAULT_FLAKEY)
+  r = Random.rand(0..100)
+  unless r < (100 - pct)
+    halt 500, "so unreliable"
+  end
+end
+
 enable :sessions
 
 configure do
@@ -218,6 +226,17 @@ before do
   sleep(1) while Sleep.instance.asleep? && request.path_info != "/livez/sleep"
   content_type :text if request.path_info.start_with? "/_cat"
   request.session_options[:skip] = !request.path_info.start_with?("/session")
+
+  if params.has_key? :flaky
+    begin
+      pct = Integer(params[:flaky])
+      pct = pct.clamp(0, 100)
+    rescue => e
+      logger.warn "#{e.message}: falling back to default flaky percentage of #{DEFAULT_FLAKEY}"
+      pct = DEFAULT_FLAKEY
+    end
+    flaky(pct)
+  end
 end
 
 helpers do