gistfile1.txt

$ cat t.lua 
local c = require "cjson"
local d = c.decode
local e = c.encode

local j1 = [[
[
    {
      "weight": 0,
      "id": "38b4ab34-f6da-4f88-9e03-aa53f75ed9f7",
      "target": "1.2.3.4:8000",
      "created_at": 1490116516932,
      "upstream_id": "413ea7ee-2740-445d-9c2e-d042e2c7a798"
    },
    {
      "weight": 20,
      "id": "8676ddb9-cd96-40ed-a537-7cc714faac44",
      "target": "1.2.3.4:8000",
      "created_at": 1490116516932,
      "upstream_id": "413ea7ee-2740-445d-9c2e-d042e2c7a798"
    }
]
]]

local j2 = [[
[
    {
      "weight": 0,
      "id": "38b4ab34-f6da-4f88-9e03-aa53f75ed9f7",
      "target": "1.2.3.4:8000",
      "created_at": 1490116516932,
      "upstream_id": "413ea7ee-2740-445d-9c2e-d042e2c7a798"
    },
    {
      "weight": 20,
      "id": "196be764-8fbe-4332-a1d4-c192c7cd6bb5",
      "target": "1.2.3.4:8000",
      "created_at": 1490116516932,
      "upstream_id": "413ea7ee-2740-445d-9c2e-d042e2c7a798"
    }
]
]]

local t1 = d(j1)
for _, target in ipairs(t1) do
  target.order = target.target..":"..target.created_at..":"..target.id
end
table.sort(t1, function(a, b) return a.order > b.order end)

for _, target in ipairs(t1) do
  print(e(target))
end

print("\n")

local t2 = d(j2)
for _, target in ipairs(t2) do
  target.order = target.target..":"..target.created_at..":"..target.id
end
table.sort(t2, function(a, b) return a.order > b.order end)

for _, target in ipairs(t2) do
  print(e(target))
end


$ resty ./t.lua 
{"order":"1.2.3.4:8000:1490116516932:8676ddb9-cd96-40ed-a537-7cc714faac44","target":"1.2.3.4:8000","id":"8676ddb9-cd96-40ed-a537-7cc714faac44","weight":20,"created_at":1490116516932,"upstream_id":"413ea7ee-2740-445d-9c2e-d042e2c7a798"}
{"order":"1.2.3.4:8000:1490116516932:38b4ab34-f6da-4f88-9e03-aa53f75ed9f7","target":"1.2.3.4:8000","id":"38b4ab34-f6da-4f88-9e03-aa53f75ed9f7","weight":0,"created_at":1490116516932,"upstream_id":"413ea7ee-2740-445d-9c2e-d042e2c7a798"}


{"order":"1.2.3.4:8000:1490116516932:38b4ab34-f6da-4f88-9e03-aa53f75ed9f7","target":"1.2.3.4:8000","id":"38b4ab34-f6da-4f88-9e03-aa53f75ed9f7","weight":0,"created_at":1490116516932,"upstream_id":"413ea7ee-2740-445d-9c2e-d042e2c7a798"}
{"order":"1.2.3.4:8000:1490116516932:196be764-8fbe-4332-a1d4-c192c7cd6bb5","target":"1.2.3.4:8000","id":"196be764-8fbe-4332-a1d4-c192c7cd6bb5","weight":20,"created_at":1490116516932,"upstream_id":"413ea7ee-2740-445d-9c2e-d042e2c7a798"}