http: listeners won't be closed if caddy fails to bind some of the addresses #7175
Description
It's possible to specify multiple addresses for caddy to bind using both Caddyfile and json, however caddy won't release those sockets if one of them fails to bind.
Consider the following Caddyfile,
{
# debug
skip_install_trust
local_certs
grace_period 10s
servers :5001 {
protocols h1 h2
}
}
localhost:5001 {
}
Let's first run a program that binds port 5004,
package main
import (
"net"
"time"
)
func main() {
_, err := net.Listen("tcp", "0.0.0.0:5004")
if err != nil {
panic(err)
}
time.Sleep(time.Minute)
}
While it's running, change the caddy config to this:
{
# debug
skip_install_trust
local_certs
grace_period 10s
servers :5001 {
protocols h1 h2
}
}
localhost:5001 localhost:5002 localhost:5003 localhost:5004 {
}
caddy will refuse to use the new config with "error":"loading config: loading new config: http app module: start: listening on :5004: listen tcp :5004: bind: Only one usage of each socket address (protocol/network address/port) is normally permitted."
Now it's impossible to bind to 5002 and 5003 because caddy uses them. Can be tested by
package main
import (
"net"
"time"
)
func main() {
_, err := net.Listen("tcp", "0.0.0.0:5002")
if err != nil {
panic(err)
}
time.Sleep(time.Minute)
}