I am trying to understand this docker file
FROM ubuntu:trusty MAINTAINER Wurstmeister RUN apt-get update; apt-get install -y unzip openjdk-7-jre-headless wget supervisor docker.io openssh-server ENV JAVA_HOME /usr/lib/jvm/java-7-openjdk-amd64/ RUN echo 'root:wurstmeister' | chpasswd RUN mkdir /var/run/sshd RUN sed -i 's/PermitRootLogin without-password/PermitRootLogin yes/' /etc/ssh/sshd_config EXPOSE 22
I understood most of the lines but I don’t understand what these below lines means?
apt-get install -y unzip openjdk-7-jre-headless wget supervisor docker.io openssh-server echo 'root:wurstmeister' | chpasswd sed -i 's/PermitRootLogin without-password/PermitRootLogin yes/' /etc/ssh/sshd_config
Can anyone help me understand? I am not sure what is the purpose of wget supervisor docker.io openssh-server in that line. Also what does echo mean there? And then also last sed line.
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Answer
apt-get install -y unzip openjdk-7-jre-headless wget supervisor docker.io openssh-server
Installs a bunch of packages using the ubuntu package manager (the base image is Ubuntu Trusty 14.04).
The -y option is used to prevent apt from asking user confirmation about installing the packages and their dependencies: the installation just proceeds without need for any input. This is needed to avoid hanging the process of building the docker image. Packages installed:
- openssh-server: so that the container can act as an ssh server and process requests from ssh clients
- wget, unzip: utilities
- java: eventually this container is used to allow users to access it via ssh, maybe those users need java
- supervisor, docker.io: I don’t see a direct usage of it in the Dockerfile itself
then
echo 'root:wurstmeister' | chpasswd
Changes password of user root to wurstmeister
sed -i 's/PermitRootLogin without-password/PermitRootLogin yes/' /etc/ssh/sshd_config
Replaces the text PermitRootLogin without-password with PermitRootLogin yes in file /etc/ssh/sshd_config to allow root user to login with password or without (e.g., with public key).
An important general note: If you run SSHD in your Docker containers, you’re doing it wrong!