May 22, 2021 Docker From entry to practice
Dockerfile consists of a line of command statements and supports comment
#
that begin with .
In general, Dockerfile is divided into four parts: basic mirror information, maintainer information, mirror operation instructions, and container startup execution instructions.
For example
# This dockerfile uses the ubuntu image
# VERSION 2 - EDITION 1
# Author: docker_user
# Command format: Instruction [arguments / command] ..
# Base image to use, this must be set as the first line
FROM ubuntu
# Maintainer: docker_user <docker_user at email.com> (@docker_user)
MAINTAINER docker_user [email protected]
# Commands to update the image
RUN echo "deb http://archive.ubuntu.com/ubuntu/ raring main universe" >> /etc/apt/sources.list
RUN apt-get update && apt-get install -y nginx
RUN echo "\ndaemon off;" >> /etc/nginx/nginx.conf
# Commands when creating a new container
CMD /usr/sbin/nginx
Where you must start by indicating the mirror name on which you are based, you must then recommend that you describe the maintainer information.
This is followed by a mirror operation instruction,
RUN
instruction,
RUN
executes a follow-up command on the mirror.
For each RUN instruction
RUN
the mirror adds a new layer and commits.
Finally, the
CMD
directive specifies the action command when the container is run.
Here is a more complex example
# Nginx
#
# VERSION 0.0.1
FROM ubuntu
MAINTAINER Victor Vieux <[email protected]>
RUN apt-get update && apt-get install -y inotify-tools nginx apache2 openssh-server
# Firefox over VNC
#
# VERSION 0.3
FROM ubuntu
# Install vnc, xvfb in order to create a 'fake' display and firefox
RUN apt-get update && apt-get install -y x11vnc xvfb firefox
RUN mkdir /.vnc
# Setup a password
RUN x11vnc -storepasswd 1234 ~/.vnc/passwd
# Autostart firefox (might not be the best way, but it does the trick)
RUN bash -c 'echo "firefox" >> /.bashrc'
EXPOSE 5900
CMD ["x11vnc", "-forever", "-usepw", "-create"]
# Multiple images example
#
# VERSION 0.1
FROM ubuntu
RUN echo foo > bar
# Will output something like ===> 907ad6c2736f
FROM ubuntu
RUN echo moo > oink
# Will output something like ===> 695d7793cbe4
# You᾿ll now have two images, 907ad6c2736f with /bar, and 695d7793cbe4 with
# /oink.