Varnish 4 vcl_deliver removes set-cookie from backend_response - cookies

Question

I've this behaviour of vcl_deliver, it removes every http.set-cookie from backend.
This is my piece of varnishlog:
- VCL_call DELIVER
- RespUnset Set-Cookie: JSESSIONID=20E1512F59F3BA8A7BAE6AC2C10B0F66; Path=/; HttpOnly
- RespUnset Set-Cookie: OpenCmsOuFqn=/; Expires=Wed, 03-Feb-2016 13:18:41 GMT; Path=/
- RespUnset Set-Cookie: OpenCmsUserName=Admin; Expires=Wed, 03-Feb-2016 13:18:41 GMT; Path=/
- RespHeader Set-Cookie: LB=fep001; path=/;
- RespHeader X-Cache: MISS
- VCL_return deliver
I may not see the configuration mistake I post it too.
This is my default.vcl config file:
vcl 4.0;
import std;
import directors;
backend fep001 {
.host = "fe1";
.port = "82";
.probe = {
.url = "/ping";
.interval = 10s;
.timeout = 1s;
.window = 1;
.threshold = 1;
.expected_response = 200;
}
}
backend fep002 {
.host = "fe2";
.port = "82";
.probe = {
.url = "/ping";
.interval = 10s;
.timeout = 1s;
.window = 1;
.threshold = 1;
.expected_response = 200;
}
}
sub vcl_init {
new cluster = directors.round_robin();
new clusterhash = directors.hash();
cluster.add_backend(fep001);
clusterhash.add_backend(fep001, 1.0);
cluster.add_backend(fep002);
clusterhash.add_backend(fep002, 1.0);
}
sub vcl_recv {
if (req.http.Cookie ~ "LB=fep[0-9]+") {
set req.backend_hint = clusterhash.backend(req.http.Cookie.LB);
} else {
set req.backend_hint = cluster.backend();
}
if (! std.healthy(req.backend_hint)) {
std.log("not healthy");
set req.backend_hint = cluster.backend();
}
if (req.http.Cookie) {
set req.http.Cookie = regsuball(req.http.Cookie, "(^|; ) *LB=[^;]+;? *", "\1");
}
if (req.method != "GET" && req.method != "HEAD") {
return(pass);
}
if (req.url ~ "^/export/.*$") {
return(hash);
}
return(pass);
}
sub vcl_backend_response {
set beresp.http.X-node = beresp.backend.name;
set beresp.http.Vary = "Accept-Encoding";
if (bereq.url ~ "^/export/.*$" && beresp.status < 400) {
set beresp.ttl = 30m;
} else {
set beresp.ttl = 0s;
}
return(deliver);
}
sub vcl_deliver {
if (obj.hits == 0 && req.http.Cookie !~ "LB=fep[0-9]+") {
set resp.http.Set-Cookie = "LB=" + resp.http.X-node + "; path=/;";
}
if (obj.hits > 0) {
set resp.http.X-Cache = "HIT:" + obj.hits;
} else {
set resp.http.X-Cache = "MISS";
}
}
How could I keep those http headers?
Thank you
Davide

Answer 1

I finally found one solution deduced from the article Proper sticky session load balancing in Varnish
It seems that Varnish 4 does not add other Set-Cookie but override it and does not add such Varnish 3 in such ways:
set resp.http.Set-Cookie = "LB=" + req.http.X-node + "; path=/;" + resp.http.Cookie;
It means that you have to use some VMODs.
I added cookie and header imports:
vcl 4.0;
import std;
import directors;
import cookie;
import header;
I changed a bit the backend selection:
cookie.parse(req.http.cookie);
if (cookie.get("LB")) {
set req.backend_hint = clusterhash.backend(cookie.get("LB"));
} else {
set req.backend_hint = cluster.backend();
}
if (! std.healthy(req.backend_hint)) {
std.log("not healthy");
set req.backend_hint = cluster.backend();
}
and in the end this is the main reason to add those VMODs:
if (obj.hits == 0 && req.http.Cookie !~ "LB=fep[0-9]+") {
header.remove(resp.http.Set-Cookie,"^LB=.*$");
header.append(resp.http.Set-Cookie,"LB=" + resp.http.X-node + "; Expires=" + cookie.format_rfc1123(now, 60m) + "; path=/;");
}
I hope this answer will help someone.