Potential connection issues with older Redix (0.11)

[talhaazeemmughal]

I am working on an app that is using Elixir version 1.10.4-otp-22 and Erlang version is 22.3.4.22. Redix version is 0.11. i am facing some issues on prod like connection issues and all. if run Redis.command(["PING"] it returns me pong and where i am trying to use it. It says redix connection error, reason closed. Is it because i am using an outdated version?

[whatyouhide]

Hi @talhaazeemmughal thanks for the issue.

and where i am trying to use it

I did not understand what this means.

It says redix connection error, reason closed

Can you connect at all? If you try to connect through gen_tcp, does it work? What's the Redis version?

[talhaazeemmughal]

by this i meant where i am trying to GET the key or SET it. It is giving me this error but it is only on prod.

and where i am trying to use it

[talhaazeemmughal]

@whatyouhide, let me add one more thing that i am using below libraries to implement rate limitting:

{:hammer_backend_redis,` "~> 6.1"},
{:hammer, "~> 6.0"},
{:redix, "~> 0.11", override: true}

also i can connect it using gen_tcp locally but let me confirm this for the prod.

[talhaazeemmughal]

@whatyouhide i am able to connect prod redis instance using gen_tcp. i am using redis 7.0.7 on prod

[whatyouhide]

Can you reproduce this in prod with a simple use case? Are you running the same Redis version locally as you are in prod?

[talhaazeemmughal]

for local,redis is dockerised and that one is using 7.2.5

[whatyouhide]

Okay, can you try using the same version? Should be easy if you're using Docker.

[talhaazeemmughal]

@whatyouhide i think it is because of hammer_backend_redis library which requires redix 0.8 and i have 0.11

[talhaazeemmughal]

why i am so sure about that is because i ran Redix.command ping one. i got pong in response and when i did Hammer.check_rate it said the connection closed error.

[talhaazeemmughal]

i upgraded the redix version to 1.1.5 and it is working fine. issue is with hammer library: open an issue there

[whatyouhide]

Nice. Moving the discussion to Hammer then, feel free to reopen if anything points to Redix being the culprit here. 🙃

[talhaazeemmughal]

@whatyouhide i updated redix from 1.1.5 to 1.5.1 and i started to have this error on my prod like environment.

** (ArgumentError) argument error
    (kernel 8.3.2) gen_tcp.erl:219: :gen_tcp.connect/4
    (redix 1.5.1) lib/redix/connector.ex:33: Redix.Connector.connect_directly/3
    (redix 1.5.1) lib/redix/socket_owner.ex:43: Redix.SocketOwner.handle_info/2
    (stdlib 3.17.2) gen_server.erl:695: :gen_server.try_dispatch/4
    (stdlib 3.17.2) gen_server.erl:771: :gen_server.handle_msg/6
    (stdlib 3.17.2) proc_lib.erl:226: :proc_lib.init_p_do_apply/3

any idea what is causing this? i am passing the config like this in config.exs:

config :redix,
  url: System.get_env("REDIS_URL", "redis://127.0.0.1:6379"),
  pool_size: 30

[whatyouhide]

How are you starting Redix @talhaazeemmughal?

[talhaazeemmughal]

@whatyouhide spawning workers for it using a custom function in :

    url = Application.get_env(:redix, :url)
    pool_size = Application.get_env(:redix, :pool_size)

    for i <- 0..(pool_size - 1) do
      args = [
        url,
        [
          name: :"redix_#{i}",
          socket_opts: redis_socket_opts(url)
        ]
      ]

      {%{id: {Redix, i}, start: {Redix, :start_link, args}}, :all}
    end

adding this list to the children and redis_socket_opts(url) adds the below is ssl is true

[
      customize_hostname_check: [
        match_fun: :public_key.pkix_verify_hostname_match_fun(:https)
      ]
    ]

[whatyouhide]

What is redis_socket_opts/1 returning?

[talhaazeemmughal]

What is redis_socket_opts/1 returning? @whatyouhide

defp redis_socket_opts("rediss://" <> _rest) do
[
customize_hostname_check: [
match_fun: :public_key.pkix_verify_hostname_match_fun(:https)
]
]
end

defp redis_socket_opts(_non_ssl_url), do: []

[whatyouhide]

@talhaazeemmughal can you reproduce this with

Redix.start_link("redis://127.0.0.1:6379", name: :redix_1, socket_opts: [])

?

[talhaazeemmughal]

@talhaazeemmughal can you reproduce this with

Redix.start_link("redis://127.0.0.1:6379", name: :redix_1, socket_opts: [])

?

give me few minutes let me check.

[talhaazeemmughal]

@whatyouhide for testing purposes, i downgraded it to 1.1.5 and then deployed it to the prod like environment. It still failed. So, i think i did some change that is actually causing this.

[whatyouhide]

Ok perfect, I'll leave this issue closed for the time being then. From the error it looks like something wrong with the argument passed to :gen_tcp.connect/4, so I would check hostname, port, and options. Let me know if you manage to reproduce it and I'll try to raise a better error from Redix if we can.

[talhaazeemmughal]

Ok perfect, I'll leave this issue closed for the time being then. From the error it looks like something wrong with the argument passed to :gen_tcp.connect/4, so I would check hostname, port, and options. Let me know if you manage to reproduce it and I'll try to raise a better error from Redix if we can.

@whatyouhide i upgraded exq library as well and this library also uses redix so it could that exq is causing this. i will have a look at it. Thank you for your quick response. i really appreciate it.