hotfix(upstream) display active targets based on proper definition

Previously we defined active upstream targets as any target with
a nonzero weight. This definition was properly implemented, but
caused confusion. As such, we redfine 'active targets' to be the most
recent entry of each nonzero target. This presents a more accurate
picture of the targets currently in use by the balancer.

kong/api/routes/upstreams.lua

@@ -148,15 +148,27 @@ return {
         if not found[entry.target] and not ignored[entry.target] then
           if entry.weight ~= 0 then
             entry.order = nil -- dont show our order key to the client
+
+            -- add what we want to send to the client in our array
             found_n = found_n + 1
             found[found_n] = entry
 
+            -- track that we found this host:port so we only show
+            -- the most recent one (kinda)
+            found[entry.target] = true
+
           else
             ignored[entry.target] = true
           end
         end
       end
 
+      -- get rid of the hash elements we tracked
+      -- so we can send this to the client
+      for i = 1, found_n do
+        found[found[i].target] = nil
+      end
+
       -- for now lets not worry about rolling our own pagination
       -- we also end up returning a "backwards" list of targets because
       -- of how we sorted- do we care?

spec/02-integration/03-admin_api/09-targets_routes_spec.lua

@@ -261,8 +261,9 @@ describe("Admin API", function()
   end)
 
   describe("/upstreams/{upstream}/targets/active/", function()
-    describe("only shows active targets", function()
+    describe("GET", function()
       local upstream_name3 = "example.com"
+      local api4
 
       before_each(function()
         local upstream3 = assert(helpers.dao.upstreams:insert {
@@ -298,12 +299,24 @@ describe("Admin API", function()
           upstream_id = upstream3.id,
         })
 
-        -- and an insert of a separate active target
+        -- an insert of a separate active target
         assert(helpers.dao.targets:insert {
           target = "api-3:80",
           weight = 10,
           upstream_id = upstream3.id,
         })
+
+        -- two target inserts (we should only see the last one)
+        assert(helpers.dao.targets:insert {
+          target = "api-4:80",
+          weight = 10,
+          upstream_id = upstream3.id,
+        })
+        api4 = assert(helpers.dao.targets:insert {
+          target = "api-4:80",
+          weight = 10,
+          upstream_id = upstream3.id,
+        })
       end)
 
       it("only shows active targets", function()
@@ -313,10 +326,11 @@ describe("Admin API", function()
         })
         assert.response(res).has.status(200)
         local json = assert.response(res).has.jsonbody()
-        assert.equal(2, #json.data)
-        assert.equal(2, json.total)
-        assert.equal("api-3:80", json.data[1].target)
-        assert.equal("api-2:80", json.data[2].target)
+        assert.equal(3, #json.data)
+        assert.equal(3, json.total)
+        assert.equal(api4.id, json.data[1].id)
+        assert.equal("api-3:80", json.data[2].target)
+        assert.equal("api-2:80", json.data[3].target)
       end)
     end)
   end)