我想以某种方式通过 docker-compose 配置两个容器，一个是 OpenVPN 客户端，另一个是 Squid HTTP 代理，公开 3128 端口以从外部访问该隧道。
现在，问题是由于某种原因，对 Squid 的请求需要整整 30 秒才能进入容器。
我开始调查该问题，似乎仅当 VPN 隧道连接并且暴露的端口位于其他容器中时才会重现。
示例 Web 服务器（模拟 Squid）正在监听 8080 端口。现在我对请求进行计时：
$ time { curl http://127.0.0.1:8080; }
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html>
<title>Directory listing for /</title>
<body>
<h2>Directory listing for /</h2>
<hr>
<ul>
</ul>
<hr>
</body>
</html>
real 0m30.066s
user 0m0.005s
sys 0m0.011s
由于某种原因，数据包需要 30 秒才能到达容器内。将 Web 服务器与 OpenVPN 放在同一个容器内即可解决该问题。阻止 OpenVPN 连接可“解决”该问题。这在 Docker for Mac 和安装在 Ubuntu 虚拟机中的 Docker CE 上均有重现。
此外还有一个类似但不幸的是没有答案的问题：当来自 dockerhost 的数据包起作用时，如何让 Docker 从远程转发数据包？
为了您的方便，我提供了完整的工作配置来重现：
docker-compose.yml
version: "3.3"
services:
vpn:
build: ./vpn
cap_add:
- net_admin
devices:
- /dev/net/tun
restart: unless-stopped
ports:
- "8080:8080"
web:
image: trinitronx/python-simplehttpserver
depends_on:
- vpn
network_mode: "service:vpn"
restart: unless-stopped
VPN/Dockerfile
FROM dperson/openvpn-client
COPY vpn.conf /vpn/vpn.conf
COPY creds.txt /vpn/creds.txt
vpn/vpn.conf
client
dev tun
proto tcp
remote 176.126.237.217 443
remote euro217.vpnbook.com 443
resolv-retry infinite
nobind
persist-key
persist-tun
auth-user-pass /vpn/creds.txt
comp-lzo
verb 3
cipher AES-128-CBC
fast-io
pull
route-delay 2
redirect-gateway
<ca>
-----BEGIN CERTIFICATE-----
MIIDyzCCAzSgAwIBAgIJAKRtpjsIvek1MA0GCSqGSIb3DQEBBQUAMIGgMQswCQYD
VQQGEwJDSDEPMA0GA1UECBMGWnVyaWNoMQ8wDQYDVQQHEwZadXJpY2gxFDASBgNV
BAoTC3ZwbmJvb2suY29tMQswCQYDVQQLEwJJVDEUMBIGA1UEAxMLdnBuYm9vay5j
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CQYDVQQGEwJDSDEPMA0GA1UECBMGWnVyaWNoMQ8wDQYDVQQHEwZadXJpY2gxFDAS
BgNVBAoTC3ZwbmJvb2suY29tMQswCQYDVQQLEwJJVDEUMBIGA1UEAxMLdnBuYm9v
ay5jb20xFDASBgNVBCkTC3ZwbmJvb2suY29tMSAwHgYJKoZIhvcNAQkBFhFhZG1p
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BBRZ4KGhnll1W+K/KJVFl/C2+KM+JjCB1QYDVR0jBIHNMIHKgBRZ4KGhnll1W+K/
KJVFl/C2+KM+JqGBpqSBozCBoDELMAkGA1UEBhMCQ0gxDzANBgNVBAgTBlp1cmlj
aDEPMA0GA1UEBxMGWnVyaWNoMRQwEgYDVQQKEwt2cG5ib29rLmNvbTELMAkGA1UE
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bTEgMB4GCSqGSIb3DQEJARYRYWRtaW5AdnBuYm9vay5jb22CCQCkbaY7CL3pNTAM
BgNVHRMEBTADAQH/MA0GCSqGSIb3DQEBBQUAA4GBAKaoCEWk2pitKjbhChjl1rLj
6FwAZ74bcX/YwXM4X4st6k2+Fgve3xzwUWTXinBIyz/WDapQmX8DHk1N3Y5FuRkv
wOgathAN44PrxLAI8kkxkngxby1xrG7LtMmpATxY7fYLOQ9yHge7RRZKDieJcX3j
+ogTneOl2w6P0xP6lyI6
-----END CERTIFICATE-----
</ca>
<cert>
-----BEGIN CERTIFICATE-----
MIID6DCCA1GgAwIBAgIBATANBgkqhkiG9w0BAQUFADCBoDELMAkGA1UEBhMCQ0gx
DzANBgNVBAgTBlp1cmljaDEPMA0GA1UEBxMGWnVyaWNoMRQwEgYDVQQKEwt2cG5i
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SDEPMA0GA1UECBMGWnVyaWNoMQ8wDQYDVQQHEwZadXJpY2gxFDASBgNVBAoTC3Zw
bmJvb2suY29tMQ8wDQYDVQQDEwZjbGllbnQxIDAeBgkqhkiG9w0BCQEWEWFkbWlu
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vQlASuzycSv1FGnNiLmg94fqzzWdmjs1XWosnLqbOwxx2Ye/1WoakSHia0pItoZk
xK7/fllm42+Qujri/ERGga5Cb/TfiP6pUQIDAQABo4IBVzCCAVMwCQYDVR0TBAIw
ADAtBglghkgBhvhCAQ0EIBYeRWFzeS1SU0EgR2VuZXJhdGVkIENlcnRpZmljYXRl
MB0GA1UdDgQWBBTDr4BCNSdOEh+Lx6+4RRK11x8XcDCB1QYDVR0jBIHNMIHKgBRZ
4KGhnll1W+K/KJVFl/C2+KM+JqGBpqSBozCBoDELMAkGA1UEBhMCQ0gxDzANBgNV
BAgTBlp1cmljaDEPMA0GA1UEBxMGWnVyaWNoMRQwEgYDVQQKEwt2cG5ib29rLmNv
bTELMAkGA1UECxMCSVQxFDASBgNVBAMTC3ZwbmJvb2suY29tMRQwEgYDVQQpEwt2
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baY7CL3pNTATBgNVHSUEDDAKBggrBgEFBQcDAjALBgNVHQ8EBAMCB4AwDQYJKoZI
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/NLsTi/Am8OP211IFLyDLvPqZuqlh/+/GOLcMCeCrMj4RYxWstNxtguGQFc=
-----END CERTIFICATE-----
</cert>
<key>
-----BEGIN RSA PRIVATE KEY-----
MIICXAIBAAKBgQCkTM/8E+JHCjskqMIwgYDrNCBTWZLa+qKkJjZ/rliJomTfVYwK
wv1AHYYU6RHpCxS1qFp3BEKLvQlASuzycSv1FGnNiLmg94fqzzWdmjs1XWosnLqb
Owxx2Ye/1WoakSHia0pItoZkxK7/fllm42+Qujri/ERGga5Cb/TfiP6pUQIDAQAB
AoGANX508WQf9nVUUFlJ8LUZnnr4U2sEr5uPPNbcQ7ImTZm8MiMOV6qo/ikesMw5
8qCS+5p26e1PJWRFENPUVhOW9c07z+nRMyHBQzFnNAFD7TiayjNk1gz1oIXarceR
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VHgSc/bZzo0q3VjNGakrA2zSXWUWrE0ybBm2wJNBYKAeskzWxoc6/gJa8mKEU+Vv
ugGb+J/tAkEAyGSEmWROUf4WX5DLl6nkjShdyv4LAQpByhiwLjmiZL7F4/irY4fo
ct2Ii5uMzwERRvHjJ7yzJJic8gkEca2adQJABxjZj4JV8DBCN3kLtlQFfMfnLhPd
9NFxTusGuvY9fM7GrXXKSMuqLwO9ZkxRHNIJsIz2N20Kt76+e1CmzUdS4QJAVvbQ
WKUgHBMRcI2s3PecuOmQspxG+D+UR3kpVBYs9F2aEZIEBuCfLuIW9Mcfd2I2NjyY
4NDSSYp1adAh/pdhVQJBANDrlnodYDu6A+a4YO9otjd+296/T8JpePI/KNxk7N0A
gm7SAhk379I6hr5NXdBbvTedlb1ULrhWV8lpwZ9HW2k=
-----END RSA PRIVATE KEY-----
</key>
vpn/creds.txt
vpnbook
5f39ntx