Varnish

varnish 是一種反向代理伺服器軟體，以記憶體方式存取 cache。透過 VCL (Varnish Configuration Language) 讓使用者設定 varnish。

安裝

在 Rocky Linux 8 安裝

dnf -y install varnish

設定

修改原本的設定檔

mv /etc/varnish/default.vcl /etc/varnish/default.vcl.bak
vi /etc/varnish/default.vcl

此設定檔只會 cache png 圖片檔案 7 天

backend default {
    .host = "127.0.0.1";  # Your app server
    .port = "8081";       # Your app server port
}

sub vcl_recv {
    # 僅對 GET 和 HEAD 快取
    if (req.method != "GET" && req.method != "HEAD") {
        return (pass);
    }

    # 僅快取 .png 圖檔，其餘請求不快取
    # 比對 URL 結尾為 .png
    if (req.url ~ "\.png$") {
        # cache
        return (hash);
    } else {
        # pass
        return (pass);
    }
}

sub vcl_backend_response {
    if (beresp.status == 200) {
        # Cache for 7 day
        set beresp.ttl = 7d;
    } else {
        set beresp.ttl = 0s;
    }
}

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

啟動

systemctl start varnish
systemctl enable varnish

修改 disk cache

Varnish 無法永久將 cache 儲存到 disk (decprecated)，但可透過 memory mapping，將記憶體的資料存放到 file

sudo systemctl edit varnish

修改 service

[Service]
ExecStart=
ExecStart=/usr/sbin/varnishd \
  -a :6081 \
  -f /etc/varnish/default.vcl \
  -s file,/var/lib/varnish/varnish_storage.bin,2G

確認 file folder 存在

sudo mkdir -p /var/lib/varnish
sudo chown varnish: /var/lib/varnish

restart Varnish

# restart varnish
sudo systemctl daemon-reexec
sudo systemctl restart varnish