Open
Description
Update: see this comment for the effect of this bug.
As the subject says, using the intercept handler with reverse_proxy causes duplication of headers received from upstream.
Using this Caddyfile:
localhost {
log
intercept {
handle_response {
header {
Header-Three Value-3
}
}
}
reverse_proxy localhost:8080
}
http://localhost:8080/ {
header {
Header-One Value-1
Header-Two Value-2
}
respond "Hello, World!"
}Note the headers received by the client:
$ curl -v https://localhost/
* Request completely sent off
< HTTP/2 200
< alt-svc: h3=":443"; ma=2592000
< content-type: text/plain; charset=utf-8
< content-type: text/plain; charset=utf-8
< date: Mon, 28 Apr 2025 21:15:40 GMT
< date: Mon, 28 Apr 2025 21:15:40 GMT
< header-one: Value-1
< header-one: Value-1
< header-three: Value-3
< header-two: Value-2
< header-two: Value-2
< server: Caddy
< via: 1.1 Caddy
< via: 1.1 Caddy
< content-length: 13
<
* Connection #0 to host localhost left intact
Hello, World!%
The workaround for reverse_proxy is using handle_response.