使用宽限模式配置 Varnish 6，vcl_hit永远不会执行

Question

当网络服务器停机进行维护时，我正在尝试将清漆 6.0.0 配置为缓存服务器，但我无法获得预期的行为。

我有下一个配置(使用宽限模式(：

vcl 4.0;
import directors;
import std;
backend default {
.host = "some.server.com";
.port = "80";
.probe = {
.url = "/health_check.php";
.interval = 5s;
.timeout = 1s;
.window = 5;
.threshold = 3;
}
}
sub vcl_recv {
std.syslog(180, "RECV: recv");
#Cache - grace mode
set req.http.grace = "none";
}
sub vcl_backend_response {
std.syslog(180, "RECV: backend");
#Cache - grace mode
set beresp.ttl = 10s;
set beresp.grace = 1h;
#set beresp.keep = 24h;
}
sub vcl_deliver {
std.syslog(180, "RECV: deliver");
#Cache
set resp.http.grace = req.http.grace;
}
sub vcl_hit {
std.syslog(180, "RECV: hit************************");
if (obj.ttl >= 0s) {
# normal hit
return (deliver);
}
# We have no fresh fish. Lets look at the stale ones.
if (std.healthy(req.backend_hint)) {
# Backend is healthy. Limit age to 10s.
if (obj.ttl + 10s > 0s) {
set req.http.grace = "normal(limited)";
return (deliver);
} else {
# No candidate for grace. Fetch a fresh object.
return(miss);
}
} else {
# backend is sick - use full grace
if (obj.ttl + obj.grace > 0s) {
set req.http.grace = "full";
return (deliver);
} else {
# no graced object.
return (miss);
}
}
}

然后，当我收到日志消息时： tail -f/var/log/messages

我只是得到下一步：

varnishd[11801]: RECV: recv
varnishd[11801]: RECV: hash
varnishd[11801]: RECV: backend
varnishd[11801]: RECV: deliver

为此，我知道子例程"vcl_hit"永远不会被执行，所以当网络服务器出现故障时，我立即从清漆而不是清漆的缓存中得到错误消息：

Error 503 Backend fetch failed
Backend fetch failed
Guru Meditation:
XID: 164960
Varnish cache server

有什么想法可以得到预期的行为吗？

Answer 1

我们使用的网页有一个用户的会话，因此我们需要识别用户何时登录。

使用以前的配置，即使 cookie 为空，默认清漆配置也不会为 cookie 的请求进行缓存。

所以我添加了一些行来使内容可缓存(在代码中解释(：

sub vcl_recv {
# intial state
set req.http.grace = "none";
# If our backend is down, unset all cookies and serve pages from cache.
if (!std.healthy(req.backend_hint)) {
unset req.http.Cookie;
}
# Are there cookies left with only spaces or that are empty?
if (req.http.cookie ~ "^s*$") {
unset req.http.cookie;
}
# NO cache si NO es get o head --> ejm, post, read, delete, etc
if (req.method != "GET" && req.method != "HEAD") {
return (pass);
}
# If server is healthy && user is in session --> no cache
if (std.healthy(req.backend_hint)) {
if (req.http.Authorization || req.http.cookie ~ "some_cookie=") {
/* Not cacheable by default */
return (pass);
}
}
return(hash);
}
sub vcl_backend_response {
#Cache - grace mode
set beresp.ttl = 10s;
#set beresp.ttl = 1h;
set beresp.grace = 1h;
set beresp.keep = 24h;
set beresp.http.Cache-Control = "max-age=3600";
}

其他子例程具有相同的配置。

Answer 2

可能是来自后端的响应是"不可缓存的"。

默认情况下，它是否设置了任何Cache-Control标头？ 还是饼干？

您可以取消设置该标头或将其设置为允许缓存的另一个值：

unset beresp.http.Cache-Control

如果您希望该标头在发送到客户端时private, no-cache以防止上游缓存，请在vcl_deliver中重置它