Merge pull request #2511 from Shopify/bug-fix

force backend sync when worker starts

rootfs/etc/nginx/lua/balancer.lua

@@ -28,6 +28,7 @@ local function get_current_backend()
   local backend = backends:get(backend_name)
 
   if not backend then
+    -- TODO(elvinefendi) maybe force backend sync here?
     ngx.log(ngx.WARN, "no backend configuration found for " .. tostring(backend_name))
   end
 
@@ -139,6 +140,7 @@ local function after_balance()
 end
 
 function _M.init_worker()
+  sync_backends() -- when worker starts, sync backends without delay
   _, err = ngx.timer.every(BACKENDS_SYNC_INTERVAL, sync_backends)
   if err then
     ngx.log(ngx.ERR, string.format("error when setting up timer.every for sync_backends: %s", tostring(err)))
@@ -155,14 +157,14 @@ function _M.call()
     return error("must be called in balancer or log, but was called in: " .. phase)
   end
 
-  ngx_balancer.set_more_tries(1)
-
   local host, port = balance()
   if not host then
     ngx.status = ngx.HTTP_SERVICE_UNAVAILABLE
-    return
+    return ngx.exit(ngx.status)
   end
 
+  ngx_balancer.set_more_tries(1)
+
   local ok
   ok, err = ngx_balancer.set_current_peer(host, port)
   if ok then

rootfs/etc/nginx/lua/test/balancer_test.lua

@@ -71,7 +71,8 @@ local function init()
     WARN = "warn",
     INFO = "info",
     ERR = "err",
-    HTTP_SERVICE_UNAVAILABLE = 503
+    HTTP_SERVICE_UNAVAILABLE = 503,
+    exit = function(status) return end,
   }
   package.loaded["ngx.balancer"] = mock_ngx_balancer
   package.loaded["resty.lrucache"] = mock_lrucache
@@ -218,13 +219,11 @@ describe("[balancer_test]", function()
         mock_backends._vals = {}
 
         local backend_get_spy = spy.on(mock_backends, "get")
-        local set_more_tries_spy = spy.on(mock_ngx_balancer, "set_more_tries")
         local set_current_peer_spy = spy.on(mock_ngx_balancer, "set_current_peer")
 
         assert.has_no_errors(balancer.call)
         assert.are_equal(ngx.status, 503)
         assert.spy(backend_get_spy).was_called_with(match.is_table(), "mock_rr_backend")
-        assert.spy(set_more_tries_spy).was_called_with(1)
         assert.spy(set_current_peer_spy).was_not_called()
       end)
     end)