Docker Dockerfile Detailed

Docker Dockerfile Detailed Category: DevOps 2014-05-15 11:0921652 People readComments (0)CollectionReportDocker

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How to use

Dockerfile is used to create a custom image that contains user-specified software dependencies, and so on. Under current directory contains Dockerfile, use command build to create a new image and name it edwardsbean/centos6-jdk1.7:

Docker build-t edwardsbean/centos6-jdk1. 7 .

Dockerfile keywords

How to write a dockerfile, in the following format:

# Comment instruction Arguments

From

Based on which mirror

RUN

Install software with

Maintainer

Image Creator

Cmd

Container the command executed at startup, but only one cmd command in a dockerfile, and more than just the last cmd.

CMD is used primarily for container when the specified service is started, and when the command of Docker run is matched to a cmd command, the command executed by CMD is replaced. Such as:
Dockerfile:

CMD echo Hello World

Run a try:

[Email protected] PC:~/software/docker-image/centos-add-test$ Docker run Centos-cmdhello World

Once the command matches:

[Email protected] PC:~/software/docker-image/centos-add-test$ Docker run centos-cmd echo Hello Edwardsbeanhello Edwardsbean

EntryPoint

Container the command executed at startup, but only one entrypoint command can be in a dockerfile, and if multiple, only the last one is executed

entrypoint replaceable feature with no cmd

USER

Which user to use to run container
Such as:

entrypoint ["memcached"] USER Daemon

EXPOSE

Container the port on which the internal service is open. On the host to use also to start container, do host-container port mapping:

Docker 127.0.0.1:33301: centos6-ssh

The 22 port of the container SSH service is mapped to the 33301 port of the host

Env

Used to set environment variables, such as:

ENV LANG en_US. utf-8 ENV lc_all en_US. utf-8

ADD

Path of file <src> Copy to container file system <dest>
All files and folders that are copied to container have permissions of 0755,uid and GID 0
If the file is in a recognized compression format, Docker will help to decompress

• If you want to add a local file, the local file must be in Docker build <path>, the specified <PATH> directory

• If you want to add a remote file, the remote file must be in Docker build <path>, specified in the <PATH> directory. Like what:

  Docker Build Github.com/creack/docker-firefox

  Docker-firefox directory must have dockerfile and file to add

Note: Build using the Docker build-< Somefile method does not add the local file directly to container. Only add URL file.

Add is only run once at the time of the build image and will not reload when running container.

VOLUME

You can attach a local folder or other container folder to container.

Workdir

Switch directory, you can switch multiple times (equivalent to CD command), Run,cmd,entrypoint effective

Onbuild

Onbuild The specified command is not executed when the image is built, but is executed in its sub-image
See here

Docker Dockerfile Detailed