Docker容器内IPv6本地连接失败，如何用curl访问localhost？

默认Docker容器禁用IPv6网络栈，导致无法通过[::1]连接localhost，报错Cannot assign requested address。以下是针对容器内IPv6调试的解决方法：

1. 临时启用容器IPv6支持 #

运行容器时添加参数，开启IPv6并禁用内核的IPv6禁用开关：

docker build . -t test-ipv6 && docker run --ipv6 --sysctl net.ipv6.conf.all.disable_ipv6=0 test-ipv6

2. 修改服务配置，监听IPv6地址 #

以Nginx为例，默认仅监听IPv4地址，需修改配置让它同时监听IPv6：

• 创建自定义nginx.conf文件：

events {
    worker_connections 1024;
}

http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    server {
        listen 80;
        listen [::]:80; # 新增IPv6监听规则

        server_name localhost;

        location / {
            root   /usr/share/nginx/html;
            index  index.html index.htm;
        }
    }
}

• 更新Dockerfile，替换默认Nginx配置：

FROM nginx
COPY nginx.conf /etc/nginx/nginx.conf
CMD nginx && sleep 1 && curl --ipv6 -s -v http://localhost

3. 验证连接效果 #

重新构建并运行容器，此时curl会成功连接到IPv6的localhost：

docker build . -t test-ipv6 && docker run --ipv6 --sysctl net.ipv6.conf.all.disable_ipv6=0 test-ipv6

成功输出示例：

*   Trying [::1]:80...
* Connected to localhost ([::1]) port 80 (#0)
> GET / HTTP/1.1
> Host: localhost
> User-Agent: curl/7.74.0
> Accept: */*
> 
< HTTP/1.1 200 OK
< Server: nginx/1.25.3
< Date: Wed, 01 Jan 2024 00:00:00 GMT
< Content-Type: text/html
< Content-Length: 615
< Last-Modified: Tue, 28 Nov 2023 10:15:00 GMT
< Connection: keep-alive
< ETag: "abc123-def456"
< Accept-Ranges: bytes
< 
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
...

可选：永久启用Docker IPv6支持 #

如果需要所有容器默认支持IPv6，修改Docker守护进程配置文件/etc/docker/daemon.json：

{
  "ipv6": true,
  "fixed-cidr-v6": "fd00::/80"
}

重启Docker服务生效：

systemctl restart docker

之后运行容器无需再添加--ipv6参数。

内容的提问来源于stack exchange，提问作者porton