如何强制 Varnish 缓存无限期保留所有缓存页面？

问题描述 投票：0回答：1

我们目前在 Magento 网站上配置了一个 Varnish 缓存服务器。我们每天运行一个缓存预热器，从站点中提取站点地图并使用它们访问站点的每个页面，以便将它们在 Varnish 缓存中可用。这在大多数情况下都很有效，并确保用户点击页面时页面是温暖的。

我们看到的问题是，有时以前随机缓存的页面需要再次缓存。我们已经禁用了 Magento 通过 VCL 清除 URL 的功能，并将 TTL 增加到 365 天，但我们仍然遇到从缓存中删除页面的问题。我已经通过 

varnishstat
确保我们没有看到任何 n_lru_nuked 页面，所以这不是内存问题。

我不确定是什么导致这些页面以看似随机的方式从 Varnish 缓存中删除。我已在下面包含了当前的 VCL 文件，是否缺少某些内容导致页面丢失缓存？如果 VCL 看起来正确，是否还有其他因素可能导致 VCL 之外的此问题？

# VCL version 5.0 is not supported so it should be 4.0 even though actually used Varnish version is 5
vcl 4.0;

import std;
# The minimal Varnish version is 5.0
# For SSL offloading, pass the following header in your proxy server or load balancer: 'X-Forwarded-Proto: https'

backend default {
    .host = "127.0.0.1";
    .port = "8181";
    .first_byte_timeout = 600s;
    .probe = {
        .url = "/pub/health_check.php";
        .timeout = 2s;
        .interval = 5s;
        .window = 10;
        .threshold = 5;
   }
}

#acl purge {
#    "127.0.0.1";
#}

sub vcl_recv {
    if (req.method == "PURGE") {
        #if (client.ip !~ purge) {
            return (synth(405, "Method not allowed"));
        #}
        # To use the X-Pool header for purging varnish during automated deployments, make sure the X-Pool header
        # has been added to the response in your backend server config. This is used, for example, by the
        # capistrano-magento2 gem for purging old content from varnish during it's deploy routine.
        #if (!req.http.X-Magento-Tags-Pattern && !req.http.X-Pool) {
        #    return (synth(400, "X-Magento-Tags-Pattern or X-Pool header required"));
        #}
        #if (req.http.X-Magento-Tags-Pattern) {
        #  ban("obj.http.X-Magento-Tags ~ " + req.http.X-Magento-Tags-Pattern);
        #}
        #if (req.http.X-Pool) {
        #  ban("obj.http.X-Pool ~ " + req.http.X-Pool);
        #}
        #return (synth(200, "Purged"));
    }

    if (req.method != "GET" &&
        req.method != "HEAD" &&
        req.method != "PUT" &&
        req.method != "POST" &&
        req.method != "TRACE" &&
        req.method != "OPTIONS" &&
        req.method != "DELETE") {
          /* Non-RFC2616 or CONNECT which is weird. */
          return (pipe);
    }

    # We only deal with GET and HEAD by default
    if (req.method != "GET" && req.method != "HEAD") {
        return (pass);
    }

    # Bypass shopping cart, checkout and search requests
    if (req.url ~ "/checkout" || req.url ~ "/catalogsearch") {
        return (pass);
    }

    # Bypass health check requests
    if (req.url ~ "/pub/health_check.php") {
        return (pass);
    }

    # Set initial grace period usage status
    set req.http.grace = "none";

    # normalize url in case of leading HTTP scheme and domain
    set req.url = regsub(req.url, "^http[s]?://", "");

    # collect all cookies
    std.collect(req.http.Cookie);

    # Compression filter. See https://www.varnish-cache.org/trac/wiki/FAQ/Compression
    if (req.http.Accept-Encoding) {
        if (req.url ~ "\.(jpg|jpeg|png|gif|gz|tgz|bz2|tbz|mp3|ogg|swf|flv)$") {
            # No point in compressing these
            unset req.http.Accept-Encoding;
        } elsif (req.http.Accept-Encoding ~ "gzip") {
            set req.http.Accept-Encoding = "gzip";
        } elsif (req.http.Accept-Encoding ~ "deflate" && req.http.user-agent !~ "MSIE") {
            set req.http.Accept-Encoding = "deflate";
        } else {
            # unknown algorithm
            unset req.http.Accept-Encoding;
        }
    }

    # Remove Google gclid parameters to minimize the cache objects
    set req.url = regsuball(req.url,"\?gclid=[^&]+$",""); # strips when QS = "?gclid=AAA"
    set req.url = regsuball(req.url,"\?gclid=[^&]+&","?"); # strips when QS = "?gclid=AAA&foo=bar"
    set req.url = regsuball(req.url,"&gclid=[^&]+",""); # strips when QS = "?foo=bar&gclid=AAA" or QS = "?foo=bar&gclid=AAA&bar=baz"

    # Static files caching
    if (req.url ~ "^/(pub/)?(media|static)/") {
        # Static files should not be cached by default
        #return (pass);

        # But if you use a few locales and don't use CDN you can enable caching static files by commenting previous line (#return (pass);) and uncommenting next 3 lines
        unset req.http.Https;
        unset req.http.X-Forwarded-Proto;
        unset req.http.Cookie;
    }

    return (hash);
}

sub vcl_hash {
#    if (req.http.cookie ~ "X-Magento-Vary=") {
#        hash_data(regsub(req.http.cookie, "^.*?X-Magento-Vary=([^;]+);*.*$", "\1"));
#    }

    # For multi site configurations to not cache each other's content
    if (req.http.host) {
        hash_data(req.http.host);
    } else {
        hash_data(server.ip);
    }

    # To make sure http users don't see ssl warning
    if (req.http.X-Forwarded-Proto) {
        hash_data(req.http.X-Forwarded-Proto);
    }
    
}

sub vcl_backend_response {

    set beresp.grace = 365d;

    if (beresp.http.content-type ~ "text") {
        set beresp.do_esi = true;
    }

    if (bereq.url ~ "\.js$" || beresp.http.content-type ~ "text") {
        set beresp.do_gzip = true;
    }

    if (beresp.http.X-Magento-Debug) {
        set beresp.http.X-Magento-Cache-Control = beresp.http.Cache-Control;
    }

    # cache only successfully responses and 404s
    if (beresp.status != 200 && beresp.status != 404) {
        set beresp.ttl = 0s;
        set beresp.uncacheable = true;
        return (deliver);
    } elsif (beresp.http.Cache-Control ~ "private") {
        set beresp.uncacheable = true;
        set beresp.ttl = 365d;
        return (deliver);
    }

    # validate if we need to cache it and prevent from setting cookie
    if (beresp.ttl > 0s && (bereq.method == "GET" || bereq.method == "HEAD")) {
        unset beresp.http.set-cookie;
    }

   # If page is not cacheable then bypass varnish for 2 minutes as Hit-For-Pass
   if (beresp.ttl <= 0s ||
       beresp.http.Surrogate-control ~ "no-store" ||
       (!beresp.http.Surrogate-Control &&
       beresp.http.Cache-Control ~ "no-cache|no-store") ||
       beresp.http.Vary == "*") {
        # Mark as Hit-For-Pass for the next 2 minutes
        set beresp.ttl = 120s;
        set beresp.uncacheable = true;
    }

    return (deliver);
}

sub vcl_deliver {
    #if (resp.http.X-Magento-Debug) {
        if (resp.http.x-varnish ~ " ") {
            set resp.http.X-Magento-Cache-Debug = "HIT";
            set resp.http.Grace = req.http.grace;
        } else {
            set resp.http.X-Magento-Cache-Debug = "MISS";
        }
    #} else {
    #    unset resp.http.Age;
    #}

    # Not letting browser to cache non-static files.
    if (resp.http.Cache-Control !~ "private" && req.url !~ "^/(pub/)?(media|static)/") {
        set resp.http.Pragma = "no-cache";
        set resp.http.Expires = "-1";
        set resp.http.Cache-Control = "no-store, no-cache, must-revalidate, max-age=0";
    }

    unset resp.http.X-Magento-Debug;
    unset resp.http.X-Magento-Tags;
    unset resp.http.X-Powered-By;
    unset resp.http.Server;
    unset resp.http.X-Varnish;
    unset resp.http.Via;
    unset resp.http.Link;
}

sub vcl_hit {
    if (obj.ttl >= 0s) {
        # Hit within TTL period
        return (deliver);
    }
    if (std.healthy(req.backend_hint)) {
        if (obj.ttl + 300s > 0s) {
            # Hit after TTL expiration, but within grace period
            set req.http.grace = "normal (healthy server)";
            return (deliver);
        } else {
            # Hit after TTL and grace expiration
            return (miss);
        }
    } else {
        # server is not healthy, retrieve from cache
        set req.http.grace = "unlimited (unhealthy server)";
        return (deliver);
    }
}
varnish varnish-vcl
1个回答
0
投票

虽然您更改了一些 

beresp.grace
和 
beresp.ttl
设置，但您并没有真正增加 VCL 文件中可缓存内容的 TTL。

您从 

set beresp.grace = 365d;
开始，这会增加容忍的陈旧程度。

在选中 

beresp.http.Cache-Control ~ "private"
的部分，您将 TTL 设置为 365 天，但这并不重要，因为这是设置 Hit-For-Miss 缓存的 TTL。您可以使用默认值 120 秒。

要解决此问题，您真正需要做的是在定义 365 天宽限期的行上方添加以下行：

set beresp.ttl = 365d;

通过在开始时设置此项，您可以将其用作默认 TTL。

您可以使用 

varnishlog
监控设置的 TTL。这是您将使用的命令：

sudo varnishlog -g request -b -i berequrl -i TTL

参见 https://varnish-cache.org/docs/7.4/reference/vsl.html 了解 TTL 标签各个字段的含义。

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