fix: override max_header_value_length using environment variable (#762)

Update runtime.exs to allow a `MAX_HEADER_LENGTH` env variable

Solves #761 by introducing an environment variable to override config -> http -> protocol_options -> max_header_value_length or leaves it at the default 4096 if no other value is specified


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Co-authored-by: Filipe Cabaço <[email protected]>

Author: Nicholas Barrow

README.md

@@ -144,6 +144,7 @@ TAILSCALE_APP_NAME         # {string}      Name of the Tailscale app.
 TAILSCALE_AUTHKEY          # {string}      Auth key for the Tailscape app.
 DNS_NODES                  # {string}      Node name used when running server in a cluster.
 MAX_CONNECTIONS            # {string}     Set the soft maximum for WebSocket connections. Defaults to '16384'.
+MAX_HEADER_LENGTH          # {string}      Set the maximum header length for connections (in bytes). Defaults to '4096'.
 NUM_ACCEPTORS              # {string}     Set the number of server processes that will relay incoming WebSocket connection requests. Defaults to '100'.
 DB_QUEUE_TARGET            # {string}     Maximum time to wait for a connection from the pool. Defaults to '5000' or 5 seconds. See for more info: https://hexdocs.pm/db_connection/DBConnection.html#start_link/2-queue-config.
 DB_QUEUE_INTERVAL          # {string}     Interval to wait to check if all connections were checked out under DB_QUEUE_TARGET. If all connections surpassed the target during this interval than the target is doubled. Defaults to '5000' or 5 seconds. See for more info: https://hexdocs.pm/db_connection/DBConnection.html#start_link/2-queue-config.

config/runtime.exs

@@ -28,6 +28,9 @@ if config_env() == :prod do
     url: [host: "#{app_name}.fly.dev", port: 80],
     http: [
       port: String.to_integer(System.get_env("PORT") || "4000"),
+      protocol_options: [
+        max_header_value_length: String.to_integer(System.get_env("MAX_HEADER_LENGTH") || "4096")
+      ],
       transport_options: [
         # max_connection is per connection supervisor
         # num_conns_sups defaults to num_acceptors

mix.exs

@@ -4,7 +4,7 @@ defmodule Realtime.MixProject do
   def project do
     [
       app: :realtime,
-      version: "2.25.49",
+      version: "2.25.50",
       elixir: "~> 1.14.0",
       elixirc_paths: elixirc_paths(Mix.env()),
       start_permanent: Mix.env() == :prod,