From 247922a093d19c4863b8911005a1fe85bb2eac8f Mon Sep 17 00:00:00 2001
From: Catherine <whitequark@whitequark.org>
Date: Mon, 22 Sep 2025 08:28:19 +0000
Subject: [PATCH] Fly.io: configure concurrency.

The default is 20, and is regularly reached by crawlers or overly
enthusiastic browsers. The actual concurrency limit is likely closer
to 500-1000.
---
 fly.toml | 30 +++++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/fly.toml b/fly.toml
index 5a9fb6b..ba76143 100644
--- a/fly.toml
+++ b/fly.toml
@@ -26,21 +26,43 @@ AUTOMEMLIMIT = "0.25"
 guest_path = "/app/config.toml"
 local_path = "config.fly.toml"
 
+# [::]:80/TCP; HTTP/1.1 and HTTP/2 (cleartext)
+
 [[services]]
 internal_port = 80
 protocol = "tcp"
-ports = [{ port = 80, handlers = ["proxy_proto"], proxy_proto_options = { version = "v2" } }]
 auto_stop_machines = "stop"
 auto_start_machines = true
 
+[[services.ports]]
+port = 80
+handlers = ["proxy_proto"]
+proxy_proto_options = { version = "v2" }
+
+[services.concurrency]
+type = "connections"
+soft_limit = 250
+
+# [::]:433/TCP; HTTP/1.1 and HTTP/2
+
 [[services]]
 internal_port = 443
 protocol = "tcp"
-ports = [{ port = 443, handlers = ["proxy_proto"], proxy_proto_options = { version = "v2" } }]
 auto_stop_machines = "stop"
 auto_start_machines = true
 
-# NB: Fly.io does not support UDP on public IPv6
+[[services.ports]]
+port = 443
+handlers = ["proxy_proto"]
+proxy_proto_options = { version = "v2" }
+
+[services.concurrency]
+type = "connections"
+soft_limit = 250
+
+# 0.0.0.0:433/UDP; HTTP/3
+# (Fly.io does not support UDP on public IPv6!)
+
 [[services]]
 internal_port = 443
 protocol = "udp"
@@ -48,6 +70,8 @@ ports = [{ port = 443 }]
 auto_stop_machines = "stop"
 auto_start_machines = true
 
+# monitoring
+
 [checks.health]
 type = "http"
 method = "get"