What's the best way to refresh a connection from time to time?

[bubiche]

Hello,

I'm using eredis_cluster with Google Cloud Memorystore for Redis Cluster, which uses their IAM Auth instead of a static password. Basically I need to generate a token (which usually expires in 1 hour) and use it as password for eredis_cluster. An authenticated connection is valid for 12 hours.

How would I "refresh" connections, i.e. generate a new token and then reconnect with it so my redis connections won't become invalid? I'm using eredis_cluster in an Elixir application (a Phoenix server) inside a Genserver like below:

defmodule MyApp.GlobalRedis do
  use GenServer

  @pool_size 5
  @cluster_name :global_redis_cluster

  def start_link(opts \\ []) do
    GenServer.start_link(__MODULE__, opts, name: __MODULE__)
  end

  @impl true
  def init(_init_arg) do
    host = ...
    port = ...
    password = Goth.fetch!(MyApp.Goth).token

    :eredis_cluster.connect(@cluster_name, [{host, port}],
           password: password,
           pool_size: @pool_size,
           pool_max_overflow: 0,
           socket_options: [
             send_timeout: 500,
             send_timeout_close: true,
             nodelay: true,
             keepalive: true
           ]
     )
  end
end

[bjosv]

I don't think there is a smooth way to just update the password on a conected cluster.
At least disconnect/1 and connect/3 with new configs should work, but If you have suggestions we are open for PRs.

[bubiche]

Thank you @bjosv, I also think the simplest way to go about it is to use disconnect and connect. Do you think there would be brief period between calling disconnect and connect where using eredis_cluster will fail and some retry logic is needed at the use site? That's one thing I'm worried about.

1 way I can think of is to make password to accept either a charlist or a function and evaluate the function everytime a password is needed, e.g. when calling AUTH for redis. But that'll be an update in eredis. Do you think that would make sense?