[系统运维]docker端口映射无法访问的解决

表现

• systemctl status docker,显示正常,可以pull，push，build
• 宿主机访问外网没问题，可以连上ubuntu的阿里的源
• 运行容器映射的端口在本机无法访问，用curl 127.0.0.1:端口，显示：

  curl: (56) Recv failure: Connection reset by peer
  

• docker build的时候，使用apt-get install xx，无法访问，哪怕镜像源是国内的阿里之类的.
  在改为 docker build --network host后又可以了

原因：

docker的网桥出问题了,导致映射端口无效，docker run -d -p 8080:80, 非常确定容器内的应用正常启动，curl 127.0.0.1:8080失败

验证问题：

用于验证的镜像

• 也可以直接下载已经写好的镜像: simple_server,直接验证

• 用golang编写一个简单的http服务，编译为simple_server

  package main
  
  import (
  	"flag"
  	"fmt"
  	"net/http"
  )
  
  func indexHandler(w http.ResponseWriter, r *http.Request) {
  	fmt.Fprintf(w, "hello world")
  }
  
  func main() {
  	var port int
  	flag.IntVar(&port, "p", 8080, "端口号,默认为8080")
  	flag.Parse()
  	fmt.Println("监控在端口", port)
  	http.HandleFunc("/", indexHandler)
  	err := http.ListenAndServe(fmt.Sprintf(":%d", port), nil)
  	if err != nil {
  		fmt.Println("错误: ", err)
  	}
  }
  
  

• 编写Dockerfile

  FROM ubuntu
  RUN echo 'deb http://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse \n\
  deb-src http://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse \n\
  deb http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse \n\
  deb-src http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse \n\	
  deb http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse \n\
  deb-src http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse \n\
  deb http://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse \n\
  deb-src http://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse \n\
  deb http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse \n\
  deb-src http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse '>/etc/apt/sources.list
  
  RUN apt-get update -y
  RUN apt-get install curl -y
  
  COPY simple_server /home/
  CMD ["/home/simple_server", "-p", "80"]
  

• 放在同一个目录，并执行: docker build . --network host -t simple_server， 目录：

  [root@ tmp]# tree server
  server
  ├── Dockerfile
  └── simple_server
  0 directories, 2 files
  

运行容器进行验证

• 运行：docker run -d -p 8080:80 simple_server
• 进入容器运行: curl 127.0.0.1, 成功打印：hello world
• 在宿主机上运行: curl 127.0.0.1:8080， 一直卡住，然后报no route 之类的错误

解决

通过重建 docker0 网络解决问题