feat(log) add balancer tries and failure information

The number of tries will be logged in the basic serializer.
If any retries occurred, then failure information will be added
as well.

CHANGELOG.md

@@ -31,6 +31,8 @@
   configured log target-url includes credentials. Thanks to
   [Amir M. Saeid](https://github.com/amir) for the contribution.
   [#2430](https://github.com/Mashape/kong/pull/2430)
+- Logging retries and failure information.
+  [#2429](https://github.com/Mashape/kong/pull/2429).
 - Plugins:
   - :fireworks: **New Request termination plugin**. This plugin allows to
     temporarily disable an API and return a pre-configured response status and

kong/kong.lua

@@ -215,9 +215,14 @@ function Kong.balancer()
     -- where the retries are executed
 
     -- record failure data
-    addr.failures = addr.failures or {}
     local state, code = get_last_failure()
-    addr.failures[addr.tries-1] = { name = state, code = code }
+    addr.failures = addr.failures or {}
+    addr.failures[addr.tries-1] = {
+      state = state,
+      code  = code,
+      ip    = addr.ip,
+      port  = addr.port,
+    }
 
     local ok, err = balancer_execute(addr)
     if not ok then

kong/plugins/log-serializers/basic.lua

@@ -8,6 +8,10 @@ function _M.serialize(ngx)
       consumer_id = ngx.ctx.authenticated_credential.consumer_id
     }
   end
+
+  local addr = ngx.ctx.balancer_address
+  local tries = addr.failures or {}
+  tries.count = addr.tries
 
   return {
     request = {
@@ -23,6 +27,7 @@ function _M.serialize(ngx)
       headers = ngx.resp.get_headers(),
       size = ngx.var.bytes_sent
     },
+    tries = tries,
     latencies = {
       kong = (ngx.ctx.KONG_ACCESS_TIME or 0) +
              (ngx.ctx.KONG_RECEIVE_TIME or 0),

spec/01-unit/13-log_serializer_spec.lua

@@ -5,7 +5,11 @@ describe("Log Serializer", function()
 
   before_each(function()
     ngx = {
-      ctx = {},
+      ctx = {
+        balancer_address = {
+          tries = 1,
+        },
+      },
       var = {
         request_uri = "/request_uri",
         scheme = "http",
@@ -60,6 +64,10 @@ describe("Log Serializer", function()
       assert.is_nil(res.api)
       assert.is_nil(res.consumer)
       assert.is_nil(res.authenticated_entity)
+
+      -- Tries
+      assert.is_table(res.tries)
+      assert.equal(1, res.tries.count)
     end)
 
     it("serializes the API object", function()
@@ -96,5 +104,30 @@ describe("Log Serializer", function()
       assert.is_nil(res.consumer)
       assert.is_nil(res.api)
     end)
+
+    it("serializes the tries and failure information", function()
+      ngx.ctx.balancer_address.tries = 3
+      ngx.ctx.balancer_address.failures = {
+        { state = "next",   code = 502, ip = "127.0.0.1", port = 1234 },
+        { state = "failed", code = nil, ip = "127.0.0.1", port = 1234 },
+      }
+
+      local res = basic.serialize(ngx)
+      assert.is_table(res)
+
+      assert.same({
+          count = 3,
+          {
+            code  = 502,
+            ip    = '127.0.0.1',
+            port  = 1234,
+            state = 'next',
+          }, {
+            ip    = '127.0.0.1',
+            port  = 1234,
+            state = 'failed',
+          }
+        }, res.tries)
+    end)
   end)
 end)