docker - 无法在Docker容器中编辑/etc/resolv.conf

Question

我想将域条目添加到我的Docker容器的/etc/resolv.conf中。

这是我的dockerFile

FROM tomcat:8.0.20-jre7
VOLUME /tmp
#RUN sed -i "s|search local|domain com.example.com|g;" /etc/resolv.conf
RUN echo "domain com.example.com" >> /etc/resolv.conf
# Expose ports.
EXPOSE 8080

我尝试了 echo和 sed。
使用 sed，在构建过程中出现错误。
sed: cannot rename /etc/sed6LcoES: Device or resource busy
但是使用 echo容器即可构建并成功运行。
但是，当我进入容器时，看不到 /etc/resolv.conf中添加了我的域。

为什么它不起作用？

注意:我已经通过在运行参数传递来使 dns-search工作
docker run -p 8080:8080 --dns-search=com.example.com -d --name myawesome my/myawesome:latest
但是我有兴趣让dockerFile工作。

Answer 1

这是设计使然。 docker引擎使用/etc/resolv.conf处理服务发现。文档指出以下内容:

How can Docker supply each container with a hostname and DNS configuration, without having to build a custom image with the hostname written inside? Its trick is to overlay three crucial /etc files inside the container with virtual files where it can write fresh information … This arrangement allows Docker to do clever things like keep resolv.conf up to date across all containers when the host machine receives new configuration over DHCP later. The exact details of how Docker maintains these files inside the container can change from one Docker version to the next, so you should leave the files themselves alone and use the following Docker options instead.

如果要覆盖/重新配置某些DNS设置，请在容器启动期间使用 --dns参数。查看更多详细信息:

Configure DNS in Docker