varnish 错误 503 后端提取仅在通过 nginx 交付的 Web 应用程序上失败（附有 varnishlog）
varnish Error 503 Backend fetch failed only on web app delivered via nginx (varnishlog attached)
我想用清漆缓存两个应用程序。一个是静态 Vue 应用程序，第二个应用程序是 Go REST API 服务器。全部在 docker 群上运行并且 API 响应良好，但是当我通过清漆查询 Vue 容器时，我得到 503 Backend fetch failed 错误。
这两个应用程序都可以通过 http://ip:8080 和 http://ip:3000/api/... 在服务器上直接访问，但如前所述，静态 Web 应用程序不响应（端口=8080）。
我知道 varnish 回复默认值是不健康的，但我不知道为什么，因为它是可访问的并且我在 default.vcl 中添加了超时等（见下文）。
我运行日志得到错误：
$ docker exec -it ... varnishlog -g raw -i backend_health
0 Backend_health - default Still sick -------- 0 3 5 0.000000 0.000000 "Open error 110 (Connection timed out)"
怀疑
我唯一的怀疑是 Vue 应用程序的 nginx 容器中的 URL 重定向以 .probe 不起作用的方式重定向请求。这是 Vue 应用程序的 nginx.conf：
server {
listen 80;
server_name _ default_server;
index index.html;
location / {
root /usr/share/nginx/html;
index index.html;
try_files $uri $uri/ /index.html;
}
}
文件
这是docker-compose.yml文件（我只是添加了host.docker.internal用于测试，当我使用不同的地址时没有任何变化，例如：client，服务器IP或host.docker.internal 作为 default.vcl 中的 host。
version: '3.9'
services:
server:
image: ...
ports:
- target: 3000
published: 3000
mode: host
networks:
- web
- db-net
depends_on:
- db
command: [ "./wait-for-it.sh", "db:5432", "--", "./streamsink" ]
deploy:
mode: replicated
replicas: 1
restart_policy:
condition: on-failure
delay: 10s
max_attempts: 10
window: 120s
placement:
constraints:
- node.role == manager
client:
image: ...
extra_hosts:
- "host.docker.internal:host-gateway"
ports:
- target: 80
published: 8080
mode: host
depends_on:
- server
networks:
- web
deploy:
restart_policy:
condition: on-failure
varnish:
image: varnish:latest
extra_hosts:
- "host.docker.internal:host-gateway"
ports:
- target: 80
published: 80
mode: host
environment:
- VARNISH_SIZE=2G
tmpfs:
- /var/lib/varnish/varnishd:exec
volumes:
- ./default.vcl:/etc/varnish/default.vcl:ro
networks:
- web
depends_on:
- client
- server
deploy:
mode: replicated
replicas: 1
restart_policy:
condition: on-failure
placement:
constraints:
- node.role == manager
...
networks:
web:
external: true
db-net:
external: true
这是 default.vcl 文件
vcl 4.1;
# import vmod_dynamic for better backend name resolution
import dynamic;
# we won't use any static backend, but Varnish still need a default one
backend default {
.host = "host.docker.internal";
.port = "8080";
.connect_timeout = 600s;
.first_byte_timeout = 600s;
.between_bytes_timeout = 600s;
.probe = {
.url = "/";
.interval = 5s;
.timeout = 50s;
.window = 5;
.threshold = 3;
}
}
backend api {
.host = "host.docker.internal";
.port = "3000";
}
sub vcl_backend_response {
set beresp.ttl = 12h;
}
sub vcl_recv {
if (req.url ~ "^/api/") {
set req.backend_hint = api;
}
else {
set req.backend_hint = default;
}
}
这是 Varnish 服务器上请求的日志：
* << Request >> 46
- Begin req 45 rxreq
- Timestamp Start: 1651165979.997021 0.000000 0.000000
- Timestamp Req: 1651165979.997021 0.000000 0.000000
- VCL_use boot
- ReqStart 172.20.0.1 59730 http
- ReqMethod GET
- ReqURL /
- ReqProtocol HTTP/1.1
- ReqHeader Host: 192.168.0.123
- ReqHeader Connection: keep-alive
- ReqHeader Cache-Control: max-age=0
- ReqHeader DNT: 1
- ReqHeader Upgrade-Insecure-Requests: 1
- ReqHeader User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36
- ReqHeader Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
- ReqHeader Accept-Encoding: gzip, deflate
- ReqHeader Accept-Language: de-DE,de;q=0.9,en-US;q=0.8,en;q=0.7
- ReqHeader sec-gpc: 1
- ReqHeader X-Forwarded-For: 172.20.0.1
- VCL_call RECV
- VCL_return pass
- VCL_call HASH
- VCL_return lookup
- VCL_call PASS
- VCL_return fetch
- Link bereq 47 pass
- Timestamp Fetch: 1651165979.997170 0.000149 0.000149
- RespProtocol HTTP/1.1
- RespStatus 503
- RespReason Backend fetch failed
- RespHeader Date: Thu, 28 Apr 2022 17:12:59 GMT
- RespHeader Server: Varnish
- RespHeader Content-Type: text/html; charset=utf-8
- RespHeader Retry-After: 5
- RespHeader X-Varnish: 46
- RespHeader Age: 0
- RespHeader Via: 1.1 varnish (Varnish/7.1)
- VCL_call DELIVER
- VCL_return deliver
- Timestamp Process: 1651165979.997182 0.000161 0.000011
- Filters
- RespHeader Content-Length: 279
- RespHeader Connection: keep-alive
- Timestamp Resp: 1651165979.997244 0.000222 0.000061
- ReqAcct 528 0 528 247 279 526
- End
** << BeReq >> 47
-- Begin bereq 46 pass
-- VCL_use boot
-- Timestamp Start: 1651165979.997101 0.000000 0.000000
-- BereqMethod GET
-- BereqURL /
-- BereqProtocol HTTP/1.1
-- BereqHeader Host: 192.168.0.123
-- BereqHeader Cache-Control: max-age=0
-- BereqHeader DNT: 1
-- BereqHeader Upgrade-Insecure-Requests: 1
-- BereqHeader User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36
-- BereqHeader Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
-- BereqHeader Accept-Encoding: gzip, deflate
-- BereqHeader Accept-Language: de-DE,de;q=0.9,en-US;q=0.8,en;q=0.7
-- BereqHeader sec-gpc: 1
-- BereqHeader X-Forwarded-For: 172.20.0.1
-- BereqHeader X-Varnish: 47
-- VCL_call BACKEND_FETCH
-- VCL_return fetch
-- Timestamp Fetch: 1651165979.997116 0.000015 0.000015
-- FetchError backend default: unhealthy
-- Timestamp Beresp: 1651165979.997121 0.000020 0.000005
-- Timestamp Error: 1651165979.997123 0.000022 0.000002
-- BerespProtocol HTTP/1.1
-- BerespStatus 503
-- BerespReason Backend fetch failed
-- BerespHeader Date: Thu, 28 Apr 2022 17:12:59 GMT
-- BerespHeader Server: Varnish
-- VCL_call BACKEND_ERROR
-- BerespHeader Content-Type: text/html; charset=utf-8
-- BerespHeader Retry-After: 5
-- VCL_return deliver
-- Storage malloc Transient
-- Length 279
-- BereqAcct 0 0 0 0 0 0
-- End
* << Request >> 48
- Begin req 45 rxreq
- Timestamp Start: 1651165980.087213 0.000000 0.000000
- Timestamp Req: 1651165980.087213 0.000000 0.000000
- VCL_use boot
- ReqStart 172.20.0.1 59730 http
- ReqMethod GET
- ReqURL /favicon.ico
- ReqProtocol HTTP/1.1
- ReqHeader Host: 192.168.0.123
- ReqHeader Connection: keep-alive
- ReqHeader User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36
- ReqHeader DNT: 1
- ReqHeader Accept: image/avif,image/webp,image/apng,image/svg+xml,image/*,*/*;q=0.8
- ReqHeader Referer: http://192.168.0.123/
- ReqHeader Accept-Encoding: gzip, deflate
- ReqHeader Accept-Language: de-DE,de;q=0.9,en-US;q=0.8,en;q=0.7
- ReqHeader sec-gpc: 1
- ReqHeader X-Forwarded-For: 172.20.0.1
- VCL_call RECV
- VCL_return pass
- VCL_call HASH
- VCL_return lookup
- VCL_call PASS
- VCL_return fetch
- Link bereq 49 pass
- Timestamp Fetch: 1651165980.087367 0.000153 0.000153
- RespProtocol HTTP/1.1
- RespStatus 503
- RespReason Backend fetch failed
- RespHeader Date: Thu, 28 Apr 2022 17:13:00 GMT
- RespHeader Server: Varnish
- RespHeader Content-Type: text/html; charset=utf-8
- RespHeader Retry-After: 5
- RespHeader X-Varnish: 48
- RespHeader Age: 0
- RespHeader Via: 1.1 varnish (Varnish/7.1)
- VCL_call DELIVER
- VCL_return deliver
- Timestamp Process: 1651165980.087382 0.000168 0.000014
- Filters
- RespHeader Content-Length: 279
- RespHeader Connection: keep-alive
- Timestamp Resp: 1651165980.087445 0.000231 0.000063
- ReqAcct 443 0 443 247 279 526
- End
** << BeReq >> 49
-- Begin bereq 48 pass
-- VCL_use boot
-- Timestamp Start: 1651165980.087307 0.000000 0.000000
-- BereqMethod GET
-- BereqURL /favicon.ico
-- BereqProtocol HTTP/1.1
-- BereqHeader Host: 192.168.0.123
-- BereqHeader User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36
-- BereqHeader DNT: 1
-- BereqHeader Accept: image/avif,image/webp,image/apng,image/svg+xml,image/*,*/*;q=0.8
-- BereqHeader Referer: http://192.168.0.123/
-- BereqHeader Accept-Encoding: gzip, deflate
-- BereqHeader Accept-Language: de-DE,de;q=0.9,en-US;q=0.8,en;q=0.7
-- BereqHeader sec-gpc: 1
-- BereqHeader X-Forwarded-For: 172.20.0.1
-- BereqHeader X-Varnish: 49
-- VCL_call BACKEND_FETCH
-- VCL_return fetch
-- Timestamp Fetch: 1651165980.087327 0.000019 0.000019
-- FetchError backend default: unhealthy
-- Timestamp Beresp: 1651165980.087332 0.000025 0.000005
-- Timestamp Error: 1651165980.087334 0.000027 0.000002
-- BerespProtocol HTTP/1.1
-- BerespStatus 503
-- BerespReason Backend fetch failed
-- BerespHeader Date: Thu, 28 Apr 2022 17:13:00 GMT
-- BerespHeader Server: Varnish
-- VCL_call BACKEND_ERROR
-- BerespHeader Content-Type: text/html; charset=utf-8
-- BerespHeader Retry-After: 5
-- VCL_return deliver
-- Storage malloc Transient
-- Length 279
-- BereqAcct 0 0 0 0 0 0
-- End
Open error 110 (Connection timed out)
尝试通过 bash shell 访问 Varnish 容器，如下图所示：
docker exec -ti varnish bash
Assuming that name of your Varnish container is varnish
运行以下命令安装一些调试依赖：
apt-get update
apt-get install -y telnet curl dnsutils
然后运行以下调试命令：
dig host.docker.internal
telnet host.docker.internal 8080
curl http://host.docker.internal:8080
- 第一个命令将检查
host.docker.internal 是否解析为 IP 地址
- 第二个命令将检查主机
host.docker.internal 是否侦听端口 8080 上的传入连接
- 第 3 个命令将在
http://host.docker.internal:8080 上尝试 HTTP 请求
请记住，Varnish 只能通过纯 HTTP 连接后端。不支持 HTTPS 后端。
根据这些调试命令的结果，你应该知道发生了什么，服务是否可达，后端是否及时响应。
解决方案比较奇怪。我只需要删除 docker 中的 ports: 部分，并使用 default.vcl 文件中的服务名称。
撰写：
client:
image: ...
ports: <-- remove
- target: 80
published: 8080
mode: host
直接访问default.vcl
中的内部端口
backend default {
.host = "client";
.port = "80";
}
这可能与 docker 群有关。不知道为什么。
我想用清漆缓存两个应用程序。一个是静态 Vue 应用程序，第二个应用程序是 Go REST API 服务器。全部在 docker 群上运行并且 API 响应良好，但是当我通过清漆查询 Vue 容器时，我得到 503 Backend fetch failed 错误。
这两个应用程序都可以通过 http://ip:8080 和 http://ip:3000/api/... 在服务器上直接访问，但如前所述，静态 Web 应用程序不响应（端口=8080）。
我知道 varnish 回复默认值是不健康的，但我不知道为什么，因为它是可访问的并且我在 default.vcl 中添加了超时等（见下文）。
我运行日志得到错误：
$ docker exec -it ... varnishlog -g raw -i backend_health
0 Backend_health - default Still sick -------- 0 3 5 0.000000 0.000000 "Open error 110 (Connection timed out)"
怀疑
我唯一的怀疑是 Vue 应用程序的 nginx 容器中的 URL 重定向以 .probe 不起作用的方式重定向请求。这是 Vue 应用程序的 nginx.conf：
server {
listen 80;
server_name _ default_server;
index index.html;
location / {
root /usr/share/nginx/html;
index index.html;
try_files $uri $uri/ /index.html;
}
}
文件
这是docker-compose.yml文件（我只是添加了host.docker.internal用于测试，当我使用不同的地址时没有任何变化，例如：client，服务器IP或host.docker.internal 作为 default.vcl 中的 host。
version: '3.9'
services:
server:
image: ...
ports:
- target: 3000
published: 3000
mode: host
networks:
- web
- db-net
depends_on:
- db
command: [ "./wait-for-it.sh", "db:5432", "--", "./streamsink" ]
deploy:
mode: replicated
replicas: 1
restart_policy:
condition: on-failure
delay: 10s
max_attempts: 10
window: 120s
placement:
constraints:
- node.role == manager
client:
image: ...
extra_hosts:
- "host.docker.internal:host-gateway"
ports:
- target: 80
published: 8080
mode: host
depends_on:
- server
networks:
- web
deploy:
restart_policy:
condition: on-failure
varnish:
image: varnish:latest
extra_hosts:
- "host.docker.internal:host-gateway"
ports:
- target: 80
published: 80
mode: host
environment:
- VARNISH_SIZE=2G
tmpfs:
- /var/lib/varnish/varnishd:exec
volumes:
- ./default.vcl:/etc/varnish/default.vcl:ro
networks:
- web
depends_on:
- client
- server
deploy:
mode: replicated
replicas: 1
restart_policy:
condition: on-failure
placement:
constraints:
- node.role == manager
...
networks:
web:
external: true
db-net:
external: true
这是 default.vcl 文件
vcl 4.1;
# import vmod_dynamic for better backend name resolution
import dynamic;
# we won't use any static backend, but Varnish still need a default one
backend default {
.host = "host.docker.internal";
.port = "8080";
.connect_timeout = 600s;
.first_byte_timeout = 600s;
.between_bytes_timeout = 600s;
.probe = {
.url = "/";
.interval = 5s;
.timeout = 50s;
.window = 5;
.threshold = 3;
}
}
backend api {
.host = "host.docker.internal";
.port = "3000";
}
sub vcl_backend_response {
set beresp.ttl = 12h;
}
sub vcl_recv {
if (req.url ~ "^/api/") {
set req.backend_hint = api;
}
else {
set req.backend_hint = default;
}
}
这是 Varnish 服务器上请求的日志：
* << Request >> 46
- Begin req 45 rxreq
- Timestamp Start: 1651165979.997021 0.000000 0.000000
- Timestamp Req: 1651165979.997021 0.000000 0.000000
- VCL_use boot
- ReqStart 172.20.0.1 59730 http
- ReqMethod GET
- ReqURL /
- ReqProtocol HTTP/1.1
- ReqHeader Host: 192.168.0.123
- ReqHeader Connection: keep-alive
- ReqHeader Cache-Control: max-age=0
- ReqHeader DNT: 1
- ReqHeader Upgrade-Insecure-Requests: 1
- ReqHeader User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36
- ReqHeader Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
- ReqHeader Accept-Encoding: gzip, deflate
- ReqHeader Accept-Language: de-DE,de;q=0.9,en-US;q=0.8,en;q=0.7
- ReqHeader sec-gpc: 1
- ReqHeader X-Forwarded-For: 172.20.0.1
- VCL_call RECV
- VCL_return pass
- VCL_call HASH
- VCL_return lookup
- VCL_call PASS
- VCL_return fetch
- Link bereq 47 pass
- Timestamp Fetch: 1651165979.997170 0.000149 0.000149
- RespProtocol HTTP/1.1
- RespStatus 503
- RespReason Backend fetch failed
- RespHeader Date: Thu, 28 Apr 2022 17:12:59 GMT
- RespHeader Server: Varnish
- RespHeader Content-Type: text/html; charset=utf-8
- RespHeader Retry-After: 5
- RespHeader X-Varnish: 46
- RespHeader Age: 0
- RespHeader Via: 1.1 varnish (Varnish/7.1)
- VCL_call DELIVER
- VCL_return deliver
- Timestamp Process: 1651165979.997182 0.000161 0.000011
- Filters
- RespHeader Content-Length: 279
- RespHeader Connection: keep-alive
- Timestamp Resp: 1651165979.997244 0.000222 0.000061
- ReqAcct 528 0 528 247 279 526
- End
** << BeReq >> 47
-- Begin bereq 46 pass
-- VCL_use boot
-- Timestamp Start: 1651165979.997101 0.000000 0.000000
-- BereqMethod GET
-- BereqURL /
-- BereqProtocol HTTP/1.1
-- BereqHeader Host: 192.168.0.123
-- BereqHeader Cache-Control: max-age=0
-- BereqHeader DNT: 1
-- BereqHeader Upgrade-Insecure-Requests: 1
-- BereqHeader User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36
-- BereqHeader Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
-- BereqHeader Accept-Encoding: gzip, deflate
-- BereqHeader Accept-Language: de-DE,de;q=0.9,en-US;q=0.8,en;q=0.7
-- BereqHeader sec-gpc: 1
-- BereqHeader X-Forwarded-For: 172.20.0.1
-- BereqHeader X-Varnish: 47
-- VCL_call BACKEND_FETCH
-- VCL_return fetch
-- Timestamp Fetch: 1651165979.997116 0.000015 0.000015
-- FetchError backend default: unhealthy
-- Timestamp Beresp: 1651165979.997121 0.000020 0.000005
-- Timestamp Error: 1651165979.997123 0.000022 0.000002
-- BerespProtocol HTTP/1.1
-- BerespStatus 503
-- BerespReason Backend fetch failed
-- BerespHeader Date: Thu, 28 Apr 2022 17:12:59 GMT
-- BerespHeader Server: Varnish
-- VCL_call BACKEND_ERROR
-- BerespHeader Content-Type: text/html; charset=utf-8
-- BerespHeader Retry-After: 5
-- VCL_return deliver
-- Storage malloc Transient
-- Length 279
-- BereqAcct 0 0 0 0 0 0
-- End
* << Request >> 48
- Begin req 45 rxreq
- Timestamp Start: 1651165980.087213 0.000000 0.000000
- Timestamp Req: 1651165980.087213 0.000000 0.000000
- VCL_use boot
- ReqStart 172.20.0.1 59730 http
- ReqMethod GET
- ReqURL /favicon.ico
- ReqProtocol HTTP/1.1
- ReqHeader Host: 192.168.0.123
- ReqHeader Connection: keep-alive
- ReqHeader User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36
- ReqHeader DNT: 1
- ReqHeader Accept: image/avif,image/webp,image/apng,image/svg+xml,image/*,*/*;q=0.8
- ReqHeader Referer: http://192.168.0.123/
- ReqHeader Accept-Encoding: gzip, deflate
- ReqHeader Accept-Language: de-DE,de;q=0.9,en-US;q=0.8,en;q=0.7
- ReqHeader sec-gpc: 1
- ReqHeader X-Forwarded-For: 172.20.0.1
- VCL_call RECV
- VCL_return pass
- VCL_call HASH
- VCL_return lookup
- VCL_call PASS
- VCL_return fetch
- Link bereq 49 pass
- Timestamp Fetch: 1651165980.087367 0.000153 0.000153
- RespProtocol HTTP/1.1
- RespStatus 503
- RespReason Backend fetch failed
- RespHeader Date: Thu, 28 Apr 2022 17:13:00 GMT
- RespHeader Server: Varnish
- RespHeader Content-Type: text/html; charset=utf-8
- RespHeader Retry-After: 5
- RespHeader X-Varnish: 48
- RespHeader Age: 0
- RespHeader Via: 1.1 varnish (Varnish/7.1)
- VCL_call DELIVER
- VCL_return deliver
- Timestamp Process: 1651165980.087382 0.000168 0.000014
- Filters
- RespHeader Content-Length: 279
- RespHeader Connection: keep-alive
- Timestamp Resp: 1651165980.087445 0.000231 0.000063
- ReqAcct 443 0 443 247 279 526
- End
** << BeReq >> 49
-- Begin bereq 48 pass
-- VCL_use boot
-- Timestamp Start: 1651165980.087307 0.000000 0.000000
-- BereqMethod GET
-- BereqURL /favicon.ico
-- BereqProtocol HTTP/1.1
-- BereqHeader Host: 192.168.0.123
-- BereqHeader User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36
-- BereqHeader DNT: 1
-- BereqHeader Accept: image/avif,image/webp,image/apng,image/svg+xml,image/*,*/*;q=0.8
-- BereqHeader Referer: http://192.168.0.123/
-- BereqHeader Accept-Encoding: gzip, deflate
-- BereqHeader Accept-Language: de-DE,de;q=0.9,en-US;q=0.8,en;q=0.7
-- BereqHeader sec-gpc: 1
-- BereqHeader X-Forwarded-For: 172.20.0.1
-- BereqHeader X-Varnish: 49
-- VCL_call BACKEND_FETCH
-- VCL_return fetch
-- Timestamp Fetch: 1651165980.087327 0.000019 0.000019
-- FetchError backend default: unhealthy
-- Timestamp Beresp: 1651165980.087332 0.000025 0.000005
-- Timestamp Error: 1651165980.087334 0.000027 0.000002
-- BerespProtocol HTTP/1.1
-- BerespStatus 503
-- BerespReason Backend fetch failed
-- BerespHeader Date: Thu, 28 Apr 2022 17:13:00 GMT
-- BerespHeader Server: Varnish
-- VCL_call BACKEND_ERROR
-- BerespHeader Content-Type: text/html; charset=utf-8
-- BerespHeader Retry-After: 5
-- VCL_return deliver
-- Storage malloc Transient
-- Length 279
-- BereqAcct 0 0 0 0 0 0
-- End
Open error 110 (Connection timed out)
尝试通过 bash shell 访问 Varnish 容器，如下图所示：
docker exec -ti varnish bash
Assuming that name of your Varnish container is
varnish
运行以下命令安装一些调试依赖：
apt-get update
apt-get install -y telnet curl dnsutils
然后运行以下调试命令：
dig host.docker.internal
telnet host.docker.internal 8080
curl http://host.docker.internal:8080
- 第一个命令将检查
host.docker.internal是否解析为 IP 地址 - 第二个命令将检查主机
host.docker.internal是否侦听端口8080 上的传入连接
- 第 3 个命令将在
http://host.docker.internal:8080 上尝试 HTTP 请求
请记住，Varnish 只能通过纯 HTTP 连接后端。不支持 HTTPS 后端。
根据这些调试命令的结果，你应该知道发生了什么，服务是否可达，后端是否及时响应。
解决方案比较奇怪。我只需要删除 docker 中的 ports: 部分，并使用 default.vcl 文件中的服务名称。
撰写：
client:
image: ...
ports: <-- remove
- target: 80
published: 8080
mode: host
直接访问default.vcl
中的内部端口backend default {
.host = "client";
.port = "80";
}
这可能与 docker 群有关。不知道为什么。