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Converted sticky session balancers into separate classes.

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This commit is contained in:
Alexander Maret-Huskinson 2019-08-30 18:07:24 +02:00
parent 9170591185
commit 881e352d68
6 changed files with 174 additions and 177 deletions
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12
rootfs/etc/nginx/lua/balancer.lua
View file

@ -6,7 +6,8 @@ local configuration = require("configuration")
local round_robin = require("balancer.round_robin")
local chash = require("balancer.chash")
local chashsubset = require("balancer.chashsubset")
local sticky = require("balancer.sticky")
local sticky_balanced = require("balancer.sticky_balanced")
local sticky_persistent = require("balancer.sticky_persistent")
local ewma = require("balancer.ewma")
-- measured in seconds
@ -19,7 +20,8 @@ local IMPLEMENTATIONS = {
round_robin = round_robin,
chash = chash,
chashsubset = chashsubset,
sticky = sticky,
sticky_balanced = sticky_balanced,
sticky_persistent = sticky_persistent,
ewma = ewma,
}
@ -30,7 +32,11 @@ local function get_implementation(backend)
local name = backend["load-balance"] or DEFAULT_LB_ALG
if backend["sessionAffinityConfig"] and backend["sessionAffinityConfig"]["name"] == "cookie" then
name = "sticky"
if backend["sessionAffinityConfig"]["mode"] == 'persistent' then
name = "sticky_persistent"
else
name = "sticky_balanced"
end
elseif backend["upstreamHashByConfig"] and backend["upstreamHashByConfig"]["upstream-hash-by"] then
if backend["upstreamHashByConfig"]["upstream-hash-by-subset"] then
name = "chashsubset"

80
rootfs/etc/nginx/lua/balancer/sticky.lua
View file

@ -1,5 +1,3 @@
local affinity_balanced = require("affinity.balanced")
local affinity_persistent = require("affinity.persistent")
local balancer_resty = require("balancer.resty")
local util = require("util")
local ck = require("resty.cookie")
@ -10,48 +8,24 @@ local string_format = string.format
local ngx_log = ngx.log
local INFO = ngx.INFO
local _M = balancer_resty:new({ name = "sticky" })
local _M = balancer_resty:new()
local DEFAULT_COOKIE_NAME = "route"
function _M.cookie_name(self)
return self.cookie_session_affinity.name or DEFAULT_COOKIE_NAME
end
local function init_affinity_mode(self, backend)
local mode = backend["sessionAffinityConfig"]["mode"] or 'balanced'
-- set default mode to 'balanced' for backwards compatibility
if mode == nil or mode == '' then
mode = 'balanced'
end
self.affinity_mode = mode
if mode == 'persistent' then
return affinity_persistent:new(self, backend)
end
-- default is 'balanced' for backwards compatibility
if mode ~= 'balanced' then
ngx.log(ngx.WARN, string.format("Invalid affinity mode '%s'! Using 'balanced' as a default.", mode))
end
return affinity_balanced:new(self, backend)
end
function _M.new(self, backend)
function _M.new(self)
local o = {
instance = nil,
affinity_mode = nil,
traffic_shaping_policy = backend.trafficShapingPolicy,
alternative_backends = backend.alternativeBackends,
cookie_session_affinity = backend["sessionAffinityConfig"]["cookieSessionAffinity"]
alternative_backends = nil,
cookie_session_affinity = nil,
traffic_shaping_policy = nil
}
setmetatable(o, self)
self.__index = self
return init_affinity_mode(o, backend)
return o
end
function _M.get_cookie(self)
@ -112,34 +86,8 @@ local function get_failed_upstreams()
return indexed_upstream_addrs
end
--- get_routing_key gets the current routing key from the cookie
-- @treturn string, string The routing key and an error message if an error occured.
function _M.get_routing_key(self)
-- interface method to get the routing key from the cookie
-- has to be overridden by an affinity mode
ngx.log(ngx.ERR, "[BUG] Failed to get routing key as no implementation has been provided!")
return nil, nil
end
--- set_routing_key sets the current routing key on the cookie
-- @tparam string key The routing key to set on the cookie.
function _M.set_routing_key(self, key)
-- interface method to set the routing key on the cookie
-- has to be overridden by an affinity mode
ngx.log(ngx.ERR, "[BUG] Failed to set routing key as no implementation has been provided!")
end
--- pick_new_upstream picks a new upstream while ignoring the given failed upstreams.
-- @tparam {[string]=boolean} A table of upstreams to ignore where the key is the endpoint and the value a boolean.
-- @treturn string, string The endpoint and its key.
function _M.pick_new_upstream(self, failed_upstreams)
-- interface method to get a new upstream
-- has to be overridden by an affinity mode
ngx.log(ngx.ERR, "[BUG] Failed to pick new upstream as no implementation has been provided!")
return nil, nil
end
local function should_set_cookie(self)
if self.cookie_session_affinity.locations and ngx.var.host then
local locs = self.cookie_session_affinity.locations[ngx.var.host]
if locs == nil then
@ -193,19 +141,11 @@ function _M.balance(self)
end
function _M.sync(self, backend)
local changed = false
-- check and reinit affinity mode before syncing the balancer which will reinit the nodes
if self.affinity_mode ~= backend.sessionAffinityConfig.mode then
changed = true
init_affinity_mode(self, backend)
end
-- reload balancer nodes
balancer_resty.sync(self, backend)
-- Reload the balancer if any of the annotations have changed.
changed = changed or not util.deep_compare(
local changed = not util.deep_compare(
self.cookie_session_affinity,
backend.sessionAffinityConfig.cookieSessionAffinity
)
@ -216,6 +156,8 @@ function _M.sync(self, backend)
ngx_log(INFO, string_format("[%s] nodes have changed for backend %s", self.name, backend.name))
self.traffic_shaping_policy = backend.trafficShapingPolicy
self.alternative_backends = backend.alternativeBackends
self.cookie_session_affinity = backend.sessionAffinityConfig.cookieSessionAffinity
end

42
rootfs/etc/nginx/lua/affinity/balanced.lua → rootfs/etc/nginx/lua/balancer/sticky_balanced.lua
View file

@ -4,13 +4,12 @@
-- will lose their session, where c is the current number of pods and n is the new number of
-- pods.
--
-- This class extends/implements the abstract class balancer.sticky.
--
local balancer_sticky = require("balancer.sticky")
local math = require("math")
local resty_chash = require("resty.chash")
local util = require("util")
local _M = {}
local _M = balancer_sticky:new()
-- Consider the situation of N upstreams one of which is failing.
-- Then the probability to obtain failing upstream after M iterations would be close to (1/N)**M.
@ -18,18 +17,33 @@ local _M = {}
-- which is much better then ~10**(-3) for 10 iterations.
local MAX_UPSTREAM_CHECKS_COUNT = 20
local function get_routing_key(self)
function _M.new(self, backend)
local nodes = util.get_nodes(backend.endpoints)
local o = {
name = "sticky_balanced",
instance = resty_chash:new(nodes)
}
setmetatable(o, self)
self.__index = self
balancer_sticky.sync(o, backend)
return o
end
function _M.get_routing_key(self)
return self:get_cookie(), nil
end
local function set_routing_key(self, key)
function _M.set_routing_key(self, key)
self:set_cookie(key)
end
local function pick_new_upstream(self, failed_upstreams)
function _M.pick_new_upstream(self, failed_upstreams)
for i = 1, MAX_UPSTREAM_CHECKS_COUNT do
local key = string.format("%s.%s.%s", ngx.now() + i, ngx.worker.pid(), math.random(999999))
local new_upstream = self.instance:find(key)
if not failed_upstreams[new_upstream] then
@ -40,18 +54,4 @@ local function pick_new_upstream(self, failed_upstreams)
return nil, nil
end
function _M.new(self, sticky_balancer, backend)
local o = sticky_balancer or {}
local nodes = util.get_nodes(backend.endpoints)
-- override sticky.balancer methods
o.instance = resty_chash:new(nodes)
o.get_routing_key = get_routing_key
o.set_routing_key = set_routing_key
o.pick_new_upstream = pick_new_upstream
return sticky_balancer
end
return _M

41
rootfs/etc/nginx/lua/affinity/persistent.lua → rootfs/etc/nginx/lua/balancer/sticky_persistent.lua
View file

@ -3,12 +3,30 @@
-- The drawback of this mode is that when scaling up a deployment, sessions will not
-- be rebalanced.
--
local balancer_sticky = require("balancer.sticky")
local util = require("util")
local util_nodemap = require("util.nodemap")
local _M = {}
local _M = balancer_sticky:new()
local function get_routing_key(self)
function _M.new(self, backend)
local nodes = util.get_nodes(backend.endpoints)
local hash_salt = backend["name"]
local o = {
name = "sticky_persistent",
instance = util_nodemap:new(nodes, hash_salt)
}
setmetatable(o, self)
self.__index = self
balancer_sticky.sync(o, backend)
return o
end
function _M.get_routing_key(self)
local cookie_value = self:get_cookie()
if cookie_value then
@ -26,28 +44,13 @@ local function get_routing_key(self)
return nil, nil
end
local function set_routing_key(self, key)
function _M.set_routing_key(self, key)
local value = string.format("%s.%s.%s", ngx.now(), ngx.worker.pid(), key)
self:set_cookie(value);
end
local function pick_new_upstream(self, failed_upstreams)
function _M.pick_new_upstream(self, failed_upstreams)
return self.instance:random_except(failed_upstreams)
end
function _M.new(self, sticky_balancer, backend)
local o = sticky_balancer or {}
local nodes = util.get_nodes(backend.endpoints)
local hash_salt = backend["name"]
-- override sticky.balancer methods
o.instance = util_nodemap:new(nodes, hash_salt)
o.get_routing_key = get_routing_key
o.set_routing_key = set_routing_key
o.pick_new_upstream = pick_new_upstream
return sticky_balancer
end
return _M

130
rootfs/etc/nginx/lua/test/balancer/sticky_test.lua
View file

@ -1,4 +1,5 @@
local sticky = require("balancer.sticky")
local sticky_balanced = require("balancer.sticky_balanced")
local sticky_persistent = require("balancer.sticky_persistent")
local cookie = require("resty.cookie")
local util = require("util")
@ -57,21 +58,27 @@ describe("Sticky", function()
describe("new(backend)", function()
context("when backend specifies cookie name", function()
it("returns an instance containing the corresponding cookie name", function()
local function test(sticky)
local sticky_balancer_instance = sticky:new(test_backend)
local test_backend_cookie_name = test_backend.sessionAffinityConfig.cookieSessionAffinity.name
assert.equal(sticky_balancer_instance:cookie_name(), test_backend_cookie_name)
end)
end
it("returns an instance containing the corresponding cookie name", function() test(sticky_balanced) end)
it("returns an instance containing the corresponding cookie name", function() test(sticky_persistent) end)
end)
context("when backend does not specify cookie name", function()
it("returns an instance with 'route' as cookie name", function()
local function test(sticky)
local temp_backend = util.deepcopy(test_backend)
temp_backend.sessionAffinityConfig.cookieSessionAffinity.name = nil
local sticky_balancer_instance = sticky:new(temp_backend)
local default_cookie_name = "route"
assert.equal(sticky_balancer_instance:cookie_name(), default_cookie_name)
end)
end
it("returns an instance with 'route' as cookie name", function() test(sticky_balanced) end)
it("returns an instance with 'route' as cookie name", function() test(sticky_persistent) end)
end)
end)
@ -79,8 +86,10 @@ describe("Sticky", function()
local mocked_cookie_new = cookie.new
before_each(function()
package.loaded["balancer.sticky"] = nil
sticky = require("balancer.sticky")
package.loaded["balancer.sticky_balanced"] = nil
package.loaded["balancer.sticky_persistent"] = nil
sticky_balanced = require("balancer.sticky_balanced")
sticky_persistent = require("balancer.sticky_persistent")
end)
after_each(function()
@ -88,13 +97,17 @@ describe("Sticky", function()
end)
context("when client doesn't have a cookie set and location is in cookie_locations", function()
it("picks an endpoint for the client", function()
local function test_pick_endpoint(sticky)
local sticky_balancer_instance = sticky:new(test_backend)
local peer = sticky_balancer_instance:balance()
assert.equal(peer, test_backend_endpoint)
end)
assert.equal(test_backend_endpoint, peer)
end
it("sets a cookie on the client", function()
it("picks an endpoint for the client", function() test_pick_endpoint(sticky_balanced) end)
it("picks an endpoint for the client", function() test_pick_endpoint(sticky_persistent) end)
local function test_set_cookie(sticky)
local s = {}
cookie.new = function(self)
local cookie_instance = {
@ -117,9 +130,12 @@ describe("Sticky", function()
local sticky_balancer_instance = sticky:new(b)
assert.has_no.errors(function() sticky_balancer_instance:balance() end)
assert.spy(s).was_called()
end)
end
it("sets a secure cookie on the client when being in ssl mode", function()
it("sets a cookie on the client", function() test_set_cookie(sticky_balanced) end)
it("sets a cookie on the client", function() test_set_cookie(sticky_persistent) end)
local function test_set_ssl_cookie(sticky)
ngx.var.https = "on"
local s = {}
cookie.new = function(self)
@ -143,10 +159,18 @@ describe("Sticky", function()
local sticky_balancer_instance = sticky:new(b)
assert.has_no.errors(function() sticky_balancer_instance:balance() end)
assert.spy(s).was_called()
end
it("sets a secure cookie on the client when being in ssl mode", function()
test_set_ssl_cookie(sticky_balanced)
end)
it("sets a secure cookie on the client when being in ssl mode", function()
test_set_ssl_cookie(sticky_persistent)
end)
end)
context("when client doesn't have a cookie set and cookie_locations contains a matching wildcard location", function()
context("when client doesn't have a cookie set and cookie_locations contains a matching wildcard location",
function()
before_each(function ()
ngx.var.host = "dev.test.com"
end)
@ -154,7 +178,7 @@ describe("Sticky", function()
ngx.var.host = "test.com"
end)
it("sets a cookie on the client", function()
local function test(sticky)
local s = {}
cookie.new = function(self)
local cookie_instance = {
@ -178,17 +202,24 @@ describe("Sticky", function()
local sticky_balancer_instance = sticky:new(b)
assert.has_no.errors(function() sticky_balancer_instance:balance() end)
assert.spy(s).was_called()
end)
end
it("sets a cookie on the client", function() test(sticky_balanced) end)
it("sets a cookie on the client", function() test(sticky_persistent) end)
end)
context("when client doesn't have a cookie set and location not in cookie_locations", function()
it("picks an endpoint for the client", function()
local function test_pick_endpoint(sticky)
local sticky_balancer_instance = sticky:new(test_backend)
local peer = sticky_balancer_instance:balance()
assert.equal(peer, test_backend_endpoint)
end)
end
it("does not set a cookie on the client", function()
it("picks an endpoint for the client", function() test_pick_endpoint(sticky_balanced) end)
it("picks an endpoint for the client", function() test_pick_endpoint(sticky_persistent) end)
local function test_no_cookie(sticky)
local s = {}
cookie.new = function(self)
local cookie_instance = {
@ -207,11 +238,15 @@ describe("Sticky", function()
local sticky_balancer_instance = sticky:new(get_test_backend())
assert.has_no.errors(function() sticky_balancer_instance:balance() end)
assert.spy(s).was_not_called()
end)
end
it("does not set a cookie on the client", function() test_no_cookie(sticky_balanced) end)
it("does not set a cookie on the client", function() test_no_cookie(sticky_persistent) end)
end)
context("when client has a cookie set", function()
it("does not set a cookie", function()
local function test_no_cookie(sticky)
local s = {}
cookie.new = function(self)
local return_obj = {
@ -224,17 +259,23 @@ describe("Sticky", function()
local sticky_balancer_instance = sticky:new(test_backend)
assert.has_no.errors(function() sticky_balancer_instance:balance() end)
assert.spy(s).was_not_called()
end)
end
it("returns the correct endpoint for the client", function()
it("does not set a cookie", test_no_cookie(sticky_balanced))
it("does not set a cookie", test_no_cookie(sticky_persistent))
local function test_correct_endpoint(sticky)
local sticky_balancer_instance = sticky:new(test_backend)
local peer = sticky_balancer_instance:balance()
assert.equal(peer, test_backend_endpoint)
end)
end
it("returns the correct endpoint for the client", function() test_correct_endpoint(sticky_balanced) end)
it("returns the correct endpoint for the client", function() test_correct_endpoint(sticky_persistent) end)
end)
end)
local function get_several_test_backends(option)
local function get_several_test_backends(change_on_failure)
return {
name = "access-router-production-web-80",
endpoints = {
@ -243,11 +284,10 @@ describe("Sticky", function()
},
sessionAffinityConfig = {
name = "cookie",
mode = option["mode"],
cookieSessionAffinity = {
name = "test_name",
hash = "sha1",
change_on_failure = option["change_on_failure"],
change_on_failure = change_on_failure,
locations = { ['test.com'] = {'/'} }
}
},
@ -258,27 +298,21 @@ describe("Sticky", function()
local mocked_cookie_new = cookie.new
before_each(function()
package.loaded["balancer.sticky"] = nil
sticky = require("balancer.sticky")
package.loaded["balancer.sticky_balanced"] = nil
package.loaded["balancer.sticky_persistent"] = nil
sticky_balanced = require("balancer.sticky_balanced")
sticky_persistent = require("balancer.sticky_persistent")
mock_ngx({ var = { location_path = "/", host = "test.com" } })
end)
after_each(function()
cookie.new = mocked_cookie_new
reset_ngx()
end)
context("when request to upstream fails", function()
it("changes upstream when change_on_failure option is true", function()
local options = {
{["change_on_failure"] = false, ["mode"] = nil},
{["change_on_failure"] = false, ["mode"] = 'balanced'},
{["change_on_failure"] = false, ["mode"] = 'persistent'},
{["change_on_failure"] = true, ["mode"] = nil},
{["change_on_failure"] = true, ["mode"] = 'balanced'},
{["change_on_failure"] = true, ["mode"] = 'persistent'}
}
for _, option in ipairs(options) do
local sticky_balancer_instance = sticky:new(get_several_test_backends(option))
local function test(sticky, change_on_failure)
local sticky_balancer_instance = sticky:new(get_several_test_backends(change_on_failure))
local old_upstream = sticky_balancer_instance:balance()
assert.is.Not.Nil(old_upstream)
@ -295,7 +329,7 @@ describe("Sticky", function()
for _ = 1, 100 do
local new_upstream = sticky_balancer_instance:balance()
if option["change_on_failure"] == false then
if change_on_failure == false then
-- upstream should be the same inspite of error, if change_on_failure option is false
assert.equal(new_upstream, old_upstream)
else
@ -304,6 +338,18 @@ describe("Sticky", function()
end
end
end
it("changes upstream when change_on_failure option is true", function()
test(sticky_balanced, 'balanced', true)
end)
it("changes upstream when change_on_failure option is true", function()
test(sticky_balanced, 'balanced', false)
end)
it("changes upstream when change_on_failure option is true", function()
test(sticky_persistent, 'balanced', true)
end)
it("changes upstream when change_on_failure option is true", function()
test(sticky_persistent, 'balanced', false)
end)
end)
end)

6
rootfs/etc/nginx/lua/test/balancer_test.lua
View file

@ -23,9 +23,9 @@ local function reset_expected_implementations()
["access-router-production-web-80"] = package.loaded["balancer.round_robin"],
["my-dummy-app-1"] = package.loaded["balancer.round_robin"],
["my-dummy-app-2"] = package.loaded["balancer.chash"],
["my-dummy-app-3"] = package.loaded["balancer.sticky"],
["my-dummy-app-3"] = package.loaded["balancer.sticky_persistent"],
["my-dummy-app-4"] = package.loaded["balancer.ewma"],
["my-dummy-app-5"] = package.loaded["balancer.sticky"],
["my-dummy-app-5"] = package.loaded["balancer.sticky_balanced"]
}
end
@ -55,7 +55,7 @@ local function reset_backends()
},
{
name = "my-dummy-app-3", ["load-balance"] = "ewma",
sessionAffinityConfig = { name = "cookie", cookieSessionAffinity = { name = "route" } }
sessionAffinityConfig = { name = "cookie", mode = 'persistent', cookieSessionAffinity = { name = "route" } }
},
{ name = "my-dummy-app-4", ["load-balance"] = "ewma", },
{