Dockerfile - 入口点不保存变量

Question

我的 Ubuntu 容器有下一个 Dockerfile

FROM ubuntu:14.04

# Install.
RUN \
  sed -i 's/# \(.*multiverse$\)/\1/g' /etc/apt/sources.list && \
  apt-get update && \
  apt-get -y upgrade && \
  apt-get install -y build-essential && \
  apt-get install -y software-properties-common && \
  apt-get install -y byobu curl git htop man unzip vim wget jq && \
  rm -rf /var/lib/apt/lists/*

# Set environment variables.
ENV HOME /root

# Define working directory.
WORKDIR /root

# Define default command.
ENTRYPOINT ["/bin/bash"]

#First create an Auth token for Sonar server
ENTRYPOINT [ "token=$(curl -X POST -H "Content-Type: application/x-www-form-urlencoded" -d "name=WindowsTokenFinal" -u admin:pass 10.0.0.2:9000/api/user_tokens/generate | jq -r '.token')"]
#
# #Save session cookies
ENTRYPOINT ["COOKIEJAR="$(mktemp)""]
#
# #Generate crumb of Jenkins
ENTRYPOINT ["CRUMB=$(curl -u "admin:pass" --cookie-jar "$COOKIEJAR" "http://10.0.0.3:8080/crumbIssuer/api/xml?xpath=concat(//crumbRequestField,%22:%22,//crumb)")"]
#
# #Create Credentials on Jenkins Server
ENTRYPOINT ["curl -X POST -u "admin:pass" --cookie "$COOKIEJAR" -H "$CRUMB" 'http://10.0.0.3:8080/credentials/store/system/domain/_/createCredentials' --data-urlencode 'json={"": "0","credentials": {"scope": "GLOBAL","id": "WindowsAutoToken","description": "Automatically generated sonar token from windows","secret": "$Token", "$class": "org.jenkinsci.plugins.plaincredentials.impl.StringCredentialsImpl"}}'"]

第一个问题是它只执行最后一个ENTRYPOINT，但如果我只运行第一个，

ENTRYPOINT [ "token=$(curl -X POST -H "Content-Type: application/x-www-form-urlencoded" -d "name=WindowsTokenFinal" -u admin:pass 10.0.0.2:9000/api/user_tokens/generate | jq -r '.token')" ]

它不保存令牌变量。

如果我在容器内执行命令就没有问题并且它运行良好，但是我需要在容器启动后运行这些命令，而不是自己运行它们。

Answer 1

我发现一个有用的模式是使用ENTRYPOINT 作为包装脚本来进行首次设置，然后使用CMD 来实际说明主进程是什么。这将允许您在入口点包装脚本中执行您需要执行的任何操作，然后将主进程作为前台作业运行。

根据您在 Dockerfile 中显示的内容，您可以将其打包到 shell 脚本中：

#!/bin/sh

#First create an Auth token for Sonar server
token=$(curl -X POST -H "Content-Type: application/x-www-form-urlencoded" -d "name=WindowsTokenFinal" -u admin:pass 10.0.0.2:9000/api/user_tokens/generate | jq -r '.token')

#Save session cookies
COOKIEJAR="$(mktemp)"

#Generate crumb of Jenkins
CRUMB=$(curl -u "admin:pass" --cookie-jar "$COOKIEJAR" "http://10.0.0.3:8080/crumbIssuer/api/xml?xpath=concat(//crumbRequestField,%22:%22,//crumb)")

#Create Credentials on Jenkins Server
curl -X POST -u "admin:pass" --cookie "$COOKIEJAR" -H "$CRUMB" 'http://10.0.0.3:8080/credentials/store/system/domain/_/createCredentials' --data-urlencode 'json={"": "0","credentials": {"scope": "GLOBAL","id": "WindowsAutoToken","description": "Automatically generated sonar token from windows","secret": "$Token", "$class": "org.jenkinsci.plugins.plaincredentials.impl.StringCredentialsImpl"}}'

# Launch the main container process
exec "$@"

然后在 Dockerfile 中，COPY 这个脚本进入，将其设置为 ENTRYPOINT，并将 CMD 设置为您希望容器运行的单个进程（可能不是交互式 shell）。

COPY entrypoint.sh /usr/local/bin
ENTRYPOINT ["/usr/local/bin/entrypoint.sh"] # must be JSON-array syntax
CMD ["my_application", "--foreground"]

请记住，一个容器只运行一个进程。如果你有ENTRYPOINT和CMD指令，the CMD gets passed as arguments to the ENTRYPOINT，如果你有多个ENTRYPOINT或CMD，只有最后一个生效，前面的被忽略。还要记住 JSON-array syntax 不做任何类型的处理或替换，所以像 $(subprocess) 调用这样的东西不适用于该语法；此外，JSON 数组语法在嵌套引号之类的东西上可能很挑剔，如果你弄错了也没有反馈，Docker 只是默默地回退到 shell-command form。