Redis connect always takes 20 seconds

Enabled the redis in pongo. Tested the following simple code. Redis connect always takes 20 seconds.

local helpers = require "spec.helpers"
local redis = require "resty.redis"

local PLUGIN_NAME = "myplugin"

local fmt = string.format
local SLEEP_TIME = 1

local REDIS_HOST = helpers.redis_host  --  host ip : "192.168.28.223" -- SERVICE_NETWORK_NAME alias: "pongo-4956b805-redis.pongo-4956b805"  --  internal ip: 192.168.32.4
local REDIS_PORT = 6379
local REDIS_DB_1 = 1
local REDIS_DB_2 = 2

for _, strategy in helpers.all_strategies({"postgres"}) do
  describe(PLUGIN_NAME .. ": (access) [#" .. strategy .. "]", function()
    local client

    lazy_setup(function()

      local bp = helpers.get_db_utils(strategy == "off" and "postgres" or strategy, nil, { PLUGIN_NAME })

      -- Inject a test route. No need to create a service, there is a default
      -- service which will echo the request.
      local route1 = bp.routes:insert({
        hosts = { "test1.com" },
      })

      -- start kong
      assert(helpers.start_kong({
        -- set the strategy
        database   = strategy,
        -- use the custom test template to create a local mock server
        nginx_conf = "spec/fixtures/custom_nginx.template",
        -- make sure our plugin gets loaded
        plugins = "bundled," .. PLUGIN_NAME,
        -- write & load declarative config, only if 'strategy=off'
        declarative_config = strategy == "off" and helpers.make_yaml_file() or nil,
      }))
    end)

    lazy_teardown(function()
      helpers.stop_kong(nil, true)
    end)

    before_each(function()
      client = helpers.proxy_client()
    end)

    after_each(function()
      if client then client:close() end
    end)

    describe("test", function()
      it("connect redis", function()

        local red = redis:new()
        red:set_timeout(2000)

        finally(function()
          if red then
            red:close()
          end
        end)

        print("connect----", os.date("%Y-%m-%d %H:%M:%S", os.time(os.date("*t"))))
        print(REDIS_HOST)
        assert(red:connect(REDIS_HOST, REDIS_PORT))
        print("select----", os.date("%Y-%m-%d %H:%M:%S", os.time(os.date("*t"))))
        assert(red:select(REDIS_DB_1))
        local size_1 = assert(red:dbsize())

        print("size----", size_1)
        local r = client:get("/status/500", {
          headers = {
            host = "test1.com"
          }
        })

        assert.response(r).has.status(500)
        ngx.sleep(SLEEP_TIME)

      end)
    end)

  end)
end

output:

Kong version: 2.8.1
[==========] Running tests from scanned files.
[----------] Global test environment setup.
[----------] Running tests from /kong-plugin/spec/myplugin/03-redis_spec.lua
2022/09/06 09:38:12 [warn] [Penlight 1.12.0] the contents of module 'pl.text' has moved into 'pl.stringx' (deprecated after 1.11.0, scheduled for removal in 2.0.0)
[ RUN      ] /kong-plugin/spec/myplugin/03-redis_spec.lua @ 57: myplugin: (access) [#postgres] test connect redis
connect----2022-09-06 09:38:48
redis
select----2022-09-06 09:39:08
size----0
[       OK ] /kong-plugin/spec/myplugin/03-redis_spec.lua @ 57: myplugin: (access) [#postgres] test connect redis (21024.36 ms)
[----------] 1 test from /kong-plugin/spec/myplugin/03-redis_spec.lua (57041.46 ms total)

[----------] Global test environment teardown.
[==========] 1 test from 1 test file ran. (57042.39 ms total)
[  PASSED  ] 1 test

If pongo expose and access redis with host ip or internal ip in docker network (like pongo-daa49114), redis connect fast.

Kong version: 2.8.1
[==========] Running tests from scanned files.
[----------] Global test environment setup.
[----------] Running tests from /kong-plugin/spec/myplugin/03-redis_spec.lua
2022/09/06 09:59:11 [warn] [Penlight 1.12.0] the contents of module 'pl.text' has moved into 'pl.stringx' (deprecated after 1.11.0, scheduled for removal in 2.0.0)
[ RUN      ] /kong-plugin/spec/myplugin/03-redis_spec.lua @ 57: myplugin: (access) [#postgres] test connect redis
connect----2022-09-06 09:59:32
192.168.28.223
select----2022-09-06 09:59:32
size----0
[       OK ] /kong-plugin/spec/myplugin/03-redis_spec.lua @ 57: myplugin: (access) [#postgres] test connect redis (1121.69 ms)
[----------] 1 test from /kong-plugin/spec/myplugin/03-redis_spec.lua (22398.11 ms total)

[----------] Global test environment teardown.
[==========] 1 test from 1 test file ran. (22399.30 ms total)
[  PASSED  ] 1 test

Host Centos8

docker version

Server: Docker Engine - Community
 Engine:
  Version:          20.10.17
  API version:      1.41 (minimum version 1.12)
  Go version:       go1.17.11
  Git commit:       a89b842
  Built:            Mon Jun  6 23:01:29 2022
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          1.6.8
  GitCommit:        9cd3357b7fd7218e4aec3eae239db1f68a5a6ec6
 runc:
  Version:          1.1.4
  GitCommit:        v1.1.4-0-g5fd4c4d
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

docker compose version Docker Compose version v2.6.0

In a windows PC installed docker for desktop with WSL2, redis connect with SERVICE_NETWORK_NAME alias (i.e. pongo-xxxxxxxx-redis.pongo-xxxxxxxx) is fast, but slow in the CentOS machine. connect with service name redis is slow too.

Host Windows10

docker version

Client: Docker Engine - Community
 Cloud integration: 1.0.17
 Version:           20.10.8
 API version:       1.41
 Go version:        go1.16.6
 Git commit:        3967b7d
 Built:             Fri Jul 30 19:54:02 2021
 OS/Arch:           linux/amd64
 Context:           default
 Experimental:      true

Server: Docker Engine - Community
 Engine:
  Version:          20.10.8
  API version:      1.41 (minimum version 1.12)
  Go version:       go1.16.6
  Git commit:       75249d8
  Built:            Fri Jul 30 19:52:10 2021
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          1.4.9
  GitCommit:        e25210fe30a0a703442421b0f60afac609f950a3
 runc:
  Version:          1.0.1
  GitCommit:        v1.0.1-0-g4144b63
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

docker compose version Docker Compose version v2.0.0-rc.1

Why did redis connect take so much time (with service name redis)? Anybody encountered this case?

Kong / kong-pongo

Redis connect always takes 20 seconds #315