Error 503 Backend fetch failed怎么办

1、为了解决这个问题，修改varnish配置文件如下:

1.用 root 用户打开:

CentOS 6: /etc/sysconfig/varnish

CentOS 7: /etc/varnish/varnish.params

Ubuntu: /etc/default/varnish

2、搜索 http_resp_hdr_len 参数

3、如果参数不存在增加 thread_pool_max

4、设置 http_resp_hdr_len

示例:-p http_resp_hdr_len=64000 \

代码片段:

# DAEMON_OPTS is used by the init script.

 DAEMON_OPTS="-a ${VARNISH_LISTEN_ADDRESS}:${VARNISH_LISTEN_PORT} \     

-f ${VARNISH_VCL_CONF} \     

-T ${VARNISH_ADMIN_LISTEN_ADDRESS}:${VARNISH_ADMIN_LISTEN_PORT} \     

-p thread_pool_min=${VARNISH_MIN_THREADS} \     

-p thread_pool_max=${VARNISH_MAX_THREADS} \     -p http_resp_hdr_len=64000 \     

-S ${VARNISH_SECRET_FILE} \     

-s ${VARNISH_STORAGE}"