From 41c925f390e4b572ea633e5f39cd6fee81a3a2bf Mon Sep 17 00:00:00 2001
From: Elvin Efendi <elvin.efendiyev@gmail.com>
Date: Tue, 13 Nov 2018 15:44:57 +0400
Subject: [PATCH 1/2] bugfix: set canary attributes when initializing balancer

---
 rootfs/etc/nginx/lua/balancer/chash.lua       | 2 ++
 rootfs/etc/nginx/lua/balancer/ewma.lua        | 2 ++
 rootfs/etc/nginx/lua/balancer/round_robin.lua | 2 ++
 rootfs/etc/nginx/lua/balancer/sticky.lua      | 2 ++
 4 files changed, 8 insertions(+)

diff --git a/rootfs/etc/nginx/lua/balancer/chash.lua b/rootfs/etc/nginx/lua/balancer/chash.lua
index d9108a8b3..ffd9f54e0 100644
--- a/rootfs/etc/nginx/lua/balancer/chash.lua
+++ b/rootfs/etc/nginx/lua/balancer/chash.lua
@@ -9,6 +9,8 @@ function _M.new(self, backend)
   local o = {
     instance = self.factory:new(nodes),
     hash_by = backend["upstream-hash-by"],
+    traffic_shaping_policy = backend.trafficShapingPolicy,
+    alternative_backends = backend.alternativeBackends,
   }
   setmetatable(o, self)
   self.__index = self
diff --git a/rootfs/etc/nginx/lua/balancer/ewma.lua b/rootfs/etc/nginx/lua/balancer/ewma.lua
index 8e4512000..0ab4e6544 100644
--- a/rootfs/etc/nginx/lua/balancer/ewma.lua
+++ b/rootfs/etc/nginx/lua/balancer/ewma.lua
@@ -120,6 +120,8 @@ end
 function _M.new(self, backend)
   local o = {
     peers = backend.endpoints,
+    traffic_shaping_policy = backend.trafficShapingPolicy,
+    alternative_backends = backend.alternativeBackends,
   }
   setmetatable(o, self)
   self.__index = self
diff --git a/rootfs/etc/nginx/lua/balancer/round_robin.lua b/rootfs/etc/nginx/lua/balancer/round_robin.lua
index db6c8e7dd..46641363e 100644
--- a/rootfs/etc/nginx/lua/balancer/round_robin.lua
+++ b/rootfs/etc/nginx/lua/balancer/round_robin.lua
@@ -8,6 +8,8 @@ function _M.new(self, backend)
   local nodes = util.get_nodes(backend.endpoints)
   local o = {
     instance = self.factory:new(nodes),
+    traffic_shaping_policy = backend.trafficShapingPolicy,
+    alternative_backends = backend.alternativeBackends,
   }
   setmetatable(o, self)
   self.__index = self
diff --git a/rootfs/etc/nginx/lua/balancer/sticky.lua b/rootfs/etc/nginx/lua/balancer/sticky.lua
index c61cef446..de9a557bc 100644
--- a/rootfs/etc/nginx/lua/balancer/sticky.lua
+++ b/rootfs/etc/nginx/lua/balancer/sticky.lua
@@ -18,6 +18,8 @@ function _M.new(self, backend)
     cookie_expires = backend["sessionAffinityConfig"]["cookieSessionAffinity"]["expires"],
     cookie_max_age = backend["sessionAffinityConfig"]["cookieSessionAffinity"]["maxage"],
     digest_func = digest_func,
+    traffic_shaping_policy = backend.trafficShapingPolicy,
+    alternative_backends = backend.alternativeBackends,
   }
   setmetatable(o, self)
   self.__index = self

From 764740a09afb108200f82813be80aa8e394ace1b Mon Sep 17 00:00:00 2001
From: Elvin Efendi <elvin.efendiyev@gmail.com>
Date: Tue, 13 Nov 2018 16:03:26 +0400
Subject: [PATCH 2/2] be more defensive when deciding alternative balancer

---
 rootfs/etc/nginx/lua/balancer.lua | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/rootfs/etc/nginx/lua/balancer.lua b/rootfs/etc/nginx/lua/balancer.lua
index 2d88f8f79..4fcf035ff 100644
--- a/rootfs/etc/nginx/lua/balancer.lua
+++ b/rootfs/etc/nginx/lua/balancer.lua
@@ -133,9 +133,25 @@ local function route_to_alternative_balancer(balancer)
   end
 
   -- TODO: support traffic shaping for n > 1 alternative backends
-  local alternative_balancer = balancers[balancer.alternative_backends[1]]
+  local backend_name = balancer.alternative_backends[1]
+  if not backend_name then
+    ngx.log(ngx.ERR, "empty alternative backend")
+    return false
+  end
 
-  local clean_target_header = util.replace_special_char(alternative_balancer.traffic_shaping_policy.header, "-", "_")
+  local alternative_balancer = balancers[backend_name]
+  if not alternative_balancer then
+    ngx.log(ngx.ERR, "no alternative balancer for backend: " .. tostring(backend_name))
+    return false
+  end
+
+  local traffic_shaping_policy =  alternative_balancer.traffic_shaping_policy
+  if not traffic_shaping_policy then
+    ngx.log(ngx.ERR, "traffic shaping policy is not set for balanacer of backend: " .. tostring(backend_name))
+    return false
+  end
+
+  local clean_target_header = util.replace_special_char(traffic_shaping_policy.header, "-", "_")
 
   local header = ngx.var["http_" .. clean_target_header]
   if header then
@@ -146,7 +162,7 @@ local function route_to_alternative_balancer(balancer)
     end
   end
 
-  local clean_target_cookie = util.replace_special_char(alternative_balancer.traffic_shaping_policy.cookie, "-", "_")
+  local clean_target_cookie = util.replace_special_char(traffic_shaping_policy.cookie, "-", "_")
 
   local cookie = ngx.var["cookie_" .. clean_target_cookie]
   if cookie then
@@ -157,7 +173,7 @@ local function route_to_alternative_balancer(balancer)
     end
   end
 
-  if math.random(100) <= alternative_balancer.traffic_shaping_policy.weight then
+  if math.random(100) <= traffic_shaping_policy.weight then
     return true
   end