Shulou(Shulou.com)06/03 Report--

1. Dockerfile creates an image-Dockerfile format

1. FROM / / specifies which basic image to be based on, and must have

Format FROM or FROM:, for example

FROM centos

FROM centos:latest

2. MAINTAINER / / specifies the author information, with or without.

Format MAINTAINER, such as

MAINTAINER aming aming@aminglinux.com

3. RUN / / Mirror Operation instruction

The format is RUN or RUN ["executable", "param1", "param2"], such as

RUN yum install httpd

RUN ["/ bin/bash", "- c", "echo hello"] / / write square brackets if there are commands, options and arguments, using commas as delimiters and double quotation marks.

4. CMD / / three formats:

CMD ["executable", "param1", "param2"]

Write directly after CMD command param1 param2 / / CMD.

CMD ["param1", "param2"] / / CMD is followed by square brackets, and parameters are written in square brackets.

RUN and CMD look alike, but CMD is used to specify that there can be only one command for container startup. For example, if you start nginx, you can write under CMD:

CMD ["/ bin/bash", "/ usr/local/nginx/sbin/nginx", "- c", "/ usr/local/nginx/conf/nginx.conf"]

5. EXPOSE

The format is EXPOSE [...], write directly to the port, such as

EXPOSE 22 80 8443

This is used to specify the ports to be mapped out, for example, inside the container we started sshd and nginx, so we need to expose ports 22 and 80. This needs to work with-P (uppercase), that is, when starting the container, you need to add-P and let it be assigned automatically, so that the listening port of the host will be randomly assigned. If you want to specify the specific port of the host, you can also use-p (lowercase) to specify.

6. ENV

Format ENV, such as

ENV PATH / usr/local/mysql/bin:$PATH

It mainly provides an environment variable for subsequent RUN instructions, and we can also define some custom variables.

ENV MYSQL_version 5.6

7. ADD format ADD

/ / add a resource to your docker, supporting both local files and remote links.

Copy a local file or directory to a directory in the container. Where src (source) is the relative path of the directory where Dockerfile is located, it can also be a url. such as

ADD

8. COPY

The format is the same as add

It is used in the same way as add, except that it does not support url remote downloads.

9. ENTRYPOINT format is similar to CMD

The command to be executed when the container starts, which is very similar to CMD, in which only one entry takes effect, and only the last one is valid if you write more than one. Unlike CMD, it is:

CMD can be overridden by the docker run instruction, but ENTRYPOINT cannot be overridden. For example, the name of the container is aming

We specify the following CMD in Dockerfile:

CMD ["/ bin/echo", "test"]

The command to start the container is docker run aming, which will output test

If the command to start the container is docker run-it aming / bin/bash, nothing will be output, such as this / bin/bash can override the instruction after CMD. So once an instruction is added at the end, the instruction after the CMD becomes invalid. But there is no problem with this ENTRYPOINT. Usually, most of them use ENTRYPOINT when using dockerfile, but rarely use CMD.

ENTRYPOINT will not be overwritten and will be executed ahead of the commands specified by CMD or docker run

ENTRYPOINT ["echo", "test"]

Docker run-it aming 123

Then test 123 is output, which is equivalent to executing the command echo test 123

10. VOLUME specifies the mount point

The format VOLUME ["/ data"] is equivalent to the directory followed by docker-v

Create a mount point that can be mounted from the local host or other container.

11. USER

Format USER daemon

Specify the user who runs the container, which is rarely used and is usually root.

12. WORKDIR

Format WORKDIR / path/to/workdir

Specify a working directory for subsequent RUN, CMD, or ENTRYPOINT. Specify a directory, and then operate in this directory.

II. Dockerfile example

Download the nginx configuration file first, or you don't have to download it, and then add it with ADD.

# wget http://www.apelearn.com/study_v2/.nginx_conf

# vim Dockerfile / / is as follows

# # Set the base image to CentOSFROM centos# File Author / MaintainerMAINTAINER aming aming@aminglinux.com# Install necessary toolsRUN yum install-y pcre-devel wget net-tools gcc zlib zlib-devel make openssl-devel# Install NginxADD http://nginx.org/download/nginx-1.8.0.tar.gz. Run tar zxvf nginx-1.8.0.tar.gzRUN mkdir-p / usr/local/nginxRUN cd nginx-1.8.0 & &. / configure-- prefix=/usr/local/nginx & & make & & Make installRUN rm-fv / usr/local/nginx/conf/nginx.conf#COPY .nginx _ conf/ usr/local/nginx/conf/nginx.confADD http://www.apelearn.com/study_v2/.nginx_conf / usr/local/nginx/conf/nginx.conf# Expose portsEXPOSE 8 Set the default command to execute when creating a new containerENTRYPOINT / usr/local/nginx/sbin/nginx & & tail-f / etc/passwd

The location of the WORKDIR is not specified, and it is in the root directory by default.

If you download the nginx configuration file first, use the COPY one, and if you don't download it, use one of the ADD below.

Description: ENTRYPOINT / usr/local/nginx/sbin/nginx & & tail-f / etc/passwd

/ / A command to be executed when the docker container starts. When the / usr/local/nginx/sbin/nginx command is executed, the nginx service will start, but when the command is executed, the container will stop automatically, so when a tail-f / etc/passwd is added, the command will never be finished and the container will run all the time.

Create a mirror:

# docker build-t centos_dockerfile_nginx.

/ /-t specifies the new image name, followed by a dot indicating the path, where to find the Dockerfile file.

There may be an error in the execution process. I found that the container cannot be connected to the network, because a third-party pipework was installed to exchange ens33 and br0, but it is still using the network of ens33, so it cannot connect to the network. The solution is to restart the docker service and let it bind the br0 automatically.

After restarting, you can check it first, in order to ensure the smooth progress of the follow-up build work. Inspection method: first enter a previous other container to see if it can be connected to the Internet, which means that the operation of the subsequent build is not a big problem.

Execute build again, and you can see the step-by-step execution process.

# docker images / / you can see the newly created image # docker run-itd-p 808880 centos_dockerfile_nginx bash

Install nginx

The second solution: first compile the nginx locally, and then directly copy the binary file (/ usr/local/nginx) into the container. You need to pay attention to whether the library files that the nginx executable depends on need to be copied to the container.

The third solution: get a new version of the nginx rpm package, copy it and install it directly.

Third, deploy services with Docker compose

Docker compose makes it easy for us to manage container startup, stop, restart and other operations quickly and efficiently. It is similar to the shell script under linux and is based on yaml syntax. In this file, we can describe the application architecture, such as what image, data volume, network mode, listening port and other information. We can define a multi-container application such as jumpserver in a compose file, and then launch the application through the compose.

Install compose as follows:

# curl-L https://github.com/docker/compose/releases/download/1.17.0-rc1/docker-compose-`uname-s`-`uname-m` > / usr/local/bin/docker-compose# chmod 755! $# docker-compose version View version information

Compose distinguishes between Version 1 and Version 2 (Compose 1.6.0 and Docker Engine 1.10.0 +). The + sign here means that version 2 comes after 1.6.0.

Version 2 supports more instructions. Version 1 does not declare that the version defaults to "version 1". Version 1 will be deprecated in the future.

4. Docker compose example

# vim docker-compose.ymlversion: "2" services: app1: image: centos_nginx ports:-"8081 centos_nginx ports 80" networks:-"net1" volumes:-/ data/:/data entrypoint: tail-f / etc/passwd app2: image: centos_with_net networks:-"net2" volumes:-/ data/:/data1 entrypoint: tail-f / etc / passwdnetworks: net1: driver: bridge net2: driver: bridge

Parsing:

Services: the next thing to do is some operations related to the container or image. First-level catalogue.

App1: the name of the container, the secondary directory.

Image: the corresponding image.

Ports: that is-p the port to be mapped.

Networks: the network used, net1,net1 is defined below.

Driver: the specified mode. Even if you don't write, the default is bridge, and you can write something else, usually using bridge. Pipework is not officially supported here, so you can only write shell scripts. Bridge, just write none here, and then assign it an extra IP.

Volumes: this is the-v option to map the local and container directories.

Entrypoint: entrypoint is also supported. Write a tail-f because the container cannot continue to run because it is opened with / bin/bash by default, so to keep the container running, write one of this. Every app should end up with a note.

# docker-compose up-d can launch two containers # docker-compose-- help# docker-compose ps/down/stop/start/rm # docker-compose ps can see the containers started with compose more clearly

Up is equivalent to down, and down can delete all compose containers.

Start and stop simply start or stop the container.

Rm: empty the stopped container.

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