Adding document on how to use HTTP/HTTPS proxy in three different scenarios

[docete]

Sometimes we need to use HTTP/HTTPS proxy in three different scenarios：

• For dockerd

  When we want to use HTTP/HTTPS proxy for “docker pull” command, we should tell the dockerd service the proxy information， which managed by systemd. So we should change the systemd configuration for dockerd. See official documentation.

  • Create a systemd drop-in directory for the docker service

  sudo mkdir -p /etc/systemd/system/docker.service.d
  

  • Create a file named /etc/systemd/system/docker.service.d/http-proxy.conf that adds the HTTP_PROXY environment variable:

  [Service]
  Environment="HTTP_PROXY=http://proxy.example.com:8080/"
  Environment="HTTPS_PROXY=http://proxy.example.com:8080/"
  Environment="NO_PROXY=localhost,127.0.0.1,.example.com"
  

  • Flush changes and restart Docker

  sudo systemctl daemon-reload
  sudo systemctl restart docker
  

• For containers

  When we want to use HTTP/HTTPS proxy in docker containers, we have to choices to tell the containers the proxy information. See official documentation.

  • Configure the docker client

    • On the docker client, create or edit the file ~/.docker/config.json and add JSON similar to the following example

    {
     "proxies":
     {
       "default":
       {
         "httpProxy": "http://proxy.example.com:8080/",
         "httpsProxy": "http://proxy.example.com:8080/",
         "noProxy": "localhost,127.0.0.1,.example.com"
       }
     }
    }    
    

  • Use environment variables

    • Set the environment variables manually

    Variable	docker run example
    HTTP_PROXY	--env HTTP_PROXY="http://proxy.example.com:8080/"
    HTTPS_PROXY	--env HTTPS_PROXY="http://proxy.example.com:8080/"
    NO_PROXY	--env NO_PROXY="localhost,127.0.0.1,.example.com"

• For build phase

  When we want to use HTTP/HTTPS proxy in build phase, we also have two choices to tell docker build client the proxy information. See official document 1 and 2

  • Use --build-arg environment variables for docker build command

  docker build \
      --build-arg "HTTP_PROXY=http://proxy.example.com:8080/" \
      --build-arg "HTTPS_PROXY=http://proxy.example.com:8080/" \
      --build-arg "NO_PROXY=localhost,127.0.0.1,.example.com" .
  

  • Set the environment variables in Dockerfile

    Variable	Dockerfile example
    HTTP_PROXY	ENV HTTP_PROXY="http://proxy.example.com:8080/"
    HTTPS_PROXY	ENV HTTPS_PROXY="http://proxy.example.com:8080/"
    NO_PROXY	ENV NO_PROXY="localhost,127.0.0.1,.example.com"

[docete]

@yeasy 最近在公司一个项目中遇到众所周知的网络问题，查询官方文档后发现docker的各个场景下使用 HTTP/HTTPS 代理存在一些细微的差别。这部分内容并没有收录到 docker_practice 中。我大致总结了3个场景，基本覆盖了 docker 使用过程中需要设置代理的各种情况。如你有空，请帮忙 review 一下。我建议在 [高级网络设置] 一节，或者 [附录一：常见问题总结] 一节中加入相关内容。如果你没有其它意见，我将创建相应的PR提交相关内容。

[yeasy]

欢迎提交PR. @docete