151 lines
5.5 KiB
Lua
151 lines
5.5 KiB
Lua
local util = require("util")
|
|
|
|
local original_ngx = ngx
|
|
local function reset_ngx()
|
|
_G.ngx = original_ngx
|
|
end
|
|
|
|
local function mock_ngx(mock)
|
|
local _ngx = mock
|
|
setmetatable(_ngx, { __index = ngx })
|
|
_G.ngx = _ngx
|
|
end
|
|
|
|
local function flush_all_ewma_stats()
|
|
ngx.shared.balancer_ewma:flush_all()
|
|
ngx.shared.balancer_ewma_last_touched_at:flush_all()
|
|
end
|
|
|
|
local function store_ewma_stats(endpoint_string, ewma, touched_at)
|
|
ngx.shared.balancer_ewma:set(endpoint_string, ewma)
|
|
ngx.shared.balancer_ewma_last_touched_at:set(endpoint_string, touched_at)
|
|
end
|
|
|
|
local function assert_ewma_stats(endpoint_string, ewma, touched_at)
|
|
assert.are.equals(ewma, ngx.shared.balancer_ewma:get(endpoint_string))
|
|
assert.are.equals(touched_at, ngx.shared.balancer_ewma_last_touched_at:get(endpoint_string))
|
|
end
|
|
|
|
|
|
describe("Balancer ewma", function()
|
|
local balancer_ewma = require("balancer.ewma")
|
|
local ngx_now = 1543238266
|
|
local backend, instance
|
|
|
|
before_each(function()
|
|
mock_ngx({ now = function() return ngx_now end, var = { balancer_ewma_score = -1 } })
|
|
|
|
backend = {
|
|
name = "namespace-service-port", ["load-balance"] = "ewma",
|
|
endpoints = {
|
|
{ address = "10.10.10.1", port = "8080", maxFails = 0, failTimeout = 0 },
|
|
{ address = "10.10.10.2", port = "8080", maxFails = 0, failTimeout = 0 },
|
|
{ address = "10.10.10.3", port = "8080", maxFails = 0, failTimeout = 0 },
|
|
}
|
|
}
|
|
store_ewma_stats("10.10.10.1:8080", 0.2, ngx_now - 1)
|
|
store_ewma_stats("10.10.10.2:8080", 0.3, ngx_now - 5)
|
|
store_ewma_stats("10.10.10.3:8080", 1.2, ngx_now - 20)
|
|
|
|
instance = balancer_ewma:new(backend)
|
|
end)
|
|
|
|
after_each(function()
|
|
reset_ngx()
|
|
flush_all_ewma_stats()
|
|
end)
|
|
|
|
describe("after_balance()", function()
|
|
it("updates EWMA stats", function()
|
|
ngx.var = { upstream_addr = "10.10.10.2:8080", upstream_connect_time = "0.02", upstream_response_time = "0.1" }
|
|
|
|
instance:after_balance()
|
|
|
|
local weight = math.exp(-5 / 10)
|
|
local expected_ewma = 0.3 * weight + 0.12 * (1.0 - weight)
|
|
|
|
assert.are.equals(expected_ewma, ngx.shared.balancer_ewma:get(ngx.var.upstream_addr))
|
|
assert.are.equals(ngx_now, ngx.shared.balancer_ewma_last_touched_at:get(ngx.var.upstream_addr))
|
|
end)
|
|
end)
|
|
|
|
describe("balance()", function()
|
|
it("returns single endpoint when the given backend has only one endpoint", function()
|
|
local single_endpoint_backend = util.deepcopy(backend)
|
|
table.remove(single_endpoint_backend.endpoints, 3)
|
|
table.remove(single_endpoint_backend.endpoints, 2)
|
|
local single_endpoint_instance = balancer_ewma:new(single_endpoint_backend)
|
|
|
|
local peer = single_endpoint_instance:balance()
|
|
|
|
assert.are.equals("10.10.10.1:8080", peer)
|
|
assert.are.equals(-1, ngx.var.balancer_ewma_score)
|
|
end)
|
|
|
|
it("picks the endpoint with lowest decayed score", function()
|
|
local two_endpoints_backend = util.deepcopy(backend)
|
|
table.remove(two_endpoints_backend.endpoints, 2)
|
|
local two_endpoints_instance = balancer_ewma:new(two_endpoints_backend)
|
|
|
|
local peer = two_endpoints_instance:balance()
|
|
|
|
-- even though 10.10.10.1:8080 has a lower ewma score
|
|
-- algorithm picks 10.10.10.3:8080 because its decayed score is even lower
|
|
assert.equal("10.10.10.3:8080", peer)
|
|
assert.are.equals(0.16240233988393523723, ngx.var.balancer_ewma_score)
|
|
end)
|
|
end)
|
|
|
|
describe("sync()", function()
|
|
it("does not reset stats when endpoints do not change", function()
|
|
local new_backend = util.deepcopy(backend)
|
|
|
|
instance:sync(new_backend)
|
|
|
|
assert.are.same(new_backend.endpoints, instance.peers)
|
|
|
|
assert_ewma_stats("10.10.10.1:8080", 0.2, ngx_now - 1)
|
|
assert_ewma_stats("10.10.10.2:8080", 0.3, ngx_now - 5)
|
|
assert_ewma_stats("10.10.10.3:8080", 1.2, ngx_now - 20)
|
|
end)
|
|
|
|
it("updates peers, deletes stats for old endpoints and sets average ewma score to new ones", function()
|
|
local new_backend = util.deepcopy(backend)
|
|
|
|
-- existing endpoint 10.10.10.2 got deleted
|
|
-- and replaced with 10.10.10.4
|
|
new_backend.endpoints[2].address = "10.10.10.4"
|
|
-- and there's one new extra endpoint
|
|
table.insert(new_backend.endpoints, { address = "10.10.10.5", port = "8080", maxFails = 0, failTimeout = 0 })
|
|
|
|
instance:sync(new_backend)
|
|
|
|
assert.are.same(new_backend.endpoints, instance.peers)
|
|
|
|
assert_ewma_stats("10.10.10.1:8080", 0.2, ngx_now - 1)
|
|
assert_ewma_stats("10.10.10.2:8080", nil, nil)
|
|
assert_ewma_stats("10.10.10.3:8080", 1.2, ngx_now - 20)
|
|
|
|
local slow_start_ewma = (0.2 + 1.2) / 2
|
|
assert_ewma_stats("10.10.10.4:8080", slow_start_ewma, ngx_now)
|
|
assert_ewma_stats("10.10.10.5:8080", slow_start_ewma, ngx_now)
|
|
end)
|
|
|
|
it("does not set slow_start_ewma when there is no existing ewma", function()
|
|
local new_backend = util.deepcopy(backend)
|
|
table.insert(new_backend.endpoints, { address = "10.10.10.4", port = "8080", maxFails = 0, failTimeout = 0 })
|
|
|
|
-- when the LB algorithm instance is just instantiated it won't have any
|
|
-- ewma value set for the initial endpoints (because it has not processed any request yet),
|
|
-- this test is trying to simulate that by flushing existing ewma values
|
|
flush_all_ewma_stats()
|
|
|
|
instance:sync(new_backend)
|
|
|
|
assert_ewma_stats("10.10.10.1:8080", nil, nil)
|
|
assert_ewma_stats("10.10.10.2:8080", nil, nil)
|
|
assert_ewma_stats("10.10.10.3:8080", nil, nil)
|
|
assert_ewma_stats("10.10.10.4:8080", nil, nil)
|
|
end)
|
|
end)
|
|
end)
|