Varnish VCL Configuration on Gentoo Linux

Full example with load balancing and grace

vcl 4.1;
import directors;

backend web1 {
    .host = "192.168.1.10"; .port = "8080";
    .probe = { .url = "/health"; .timeout = 5s; .interval = 10s; .window = 5; .threshold = 3; }
}
backend web2 {
    .host = "192.168.1.11"; .port = "8080";
    .probe = { .url = "/health"; .timeout = 5s; .interval = 10s; }
}

sub vcl_init {
    new lb = directors.round_robin();
    lb.add_backend(web1);
    lb.add_backend(web2);
}

sub vcl_recv {
    set req.backend_hint = lb.backend();
    if (req.method != "GET" && req.method != "HEAD") { return (pass); }
    if (req.http.Authorization) { return (pass); }
    if (req.url ~ "\.(css|js|png|jpg|gif|ico|woff2?)$") {
        unset req.http.Cookie;
        return (hash);
    }
}

sub vcl_backend_response {
    set beresp.grace = 30s;
    if (bereq.url ~ "\.(css|js|png|jpg|gif|ico|woff2?)$") {
        unset beresp.http.Set-Cookie;
        set beresp.ttl = 7d;
    }
    if (beresp.status >= 500) {
        set beresp.ttl = 0s; set beresp.uncacheable = true; return (deliver);
    }
}

sub vcl_deliver {
    if (obj.hits > 0) {
        set resp.http.X-Cache = "HIT";
    } else {
        set resp.http.X-Cache = "MISS";
    }
    unset resp.http.X-Varnish;
    unset resp.http.Via;
}

Purge by URL pattern

varnishadm "ban req.http.host == example.com && req.url ~ /blog"