Dockerfile operation instructions
| instructions | Meaning |
|---|---|
| FROM Mirror | Specifies the mirror on which the new image is based. The first instruction must be the FROM instruction, which is required for each image created |
| MAINTAINER Name | Maintainer information describing the mirror |
| RUN command | Execute commands on the mirror on which they are based and submit them to a new mirror |
| CMD ["Program to run", ""Parameter 1","Parameter 2"] | A command or script to run when an instruction starts a container, dockerfile can only have one CMD command, and only the last one can be executed if multiple commands are specified |
| EXPOSE port number | Specify the port to open when a new image is loaded into the docker |
| ENV Environment Variable Value | Set the value of an environment variable, which the subsequent RUN s will use |
| ADD source/directory target/directory | Copy the source file to the target file, either in the same directory as the Dockerfile or in a URL |
| COPY source/directory target/directory | Copy the files/directories on the local host to the destination location. Source files/directories Rain Dockerfile s in the same directory |
| VOLUME ["Directory"] | Create a mount point in a container |
| USER username/UID | Specify the user when running the container |
| WORKDIR Path | Specify a working directory for subsequent RUN/CMD/ENTRYPOINT |
| ONBUILD command | Specifies the command to run when the generated image is used as a base image |
| HEALTHCHECK | Health examination |
Making nginx Mirrors
[root@docker2 ~]# mkdir nginx [root@docker2 ~]# cd nginx [root@docker2 nginx]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE [root@docker2 nginx]# vim Dockerfile FROM centos:7 //Based on the underlying environment MAINTAINER nginx image //Mirror Information RUN yum -y update && yum -y install gcc gcc-c++ make pcre-devel zlib-devel //Update Base Environment RUN useradd -M -s /sbin/nologin nginx //Create an administrative user ADD nginx-1.12.2.tar.gz /usr/local/src //decompression WORKDIR /usr/local/src/nginx-1.12.2 //Enter Directory RUN ./configure --prefix=/usr/local/nginx \ //assign work directory --user=nginx \ --group=nginx \ --with-http_stub_status_module && make && make install ENV PATH /usr/local/nginx/sbin:$PATH //Set variable environment EXPOSE 80 //Expose port 80 RUN echo "daemon off;" >> /usr/local/nginx/conf/nginx.conf //Close daemon CMD nginx //Execute default command to open nginx [root@docker2 nginx]# ls Dockerfile nginx-1.12.2.tar.gz [root@localhost nginx]# Docker build-t nginx:new. //Build Mirror ....................... Successfully built 8539f950fcb7 Successfully tagged nginx:new [root@localhost nginx]# docker images //See if the image was made successfully REPOSITORY TAG IMAGE ID CREATED SIZE nginx new 8539f950fcb7 7 seconds ago 544MB centos 7 8652b9f0cb4c 10 months ago 204MB [root@localhost nginx]# Docker run-d-P nginx:new//Open container ce3b9cc6ce37a8e0c6e360e7c0002158edad03944383ee3efb962f990f12f3e5 [root@localhost nginx]# Docker PS-A //view port CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES ce3b9cc6ce37 nginx:new "/bin/sh -c nginx" 5 seconds ago Up 4 seconds 0.0.0.0:49153->80/tcp, :::49153->80/tcp heuristic_ritchie
Tomcat
[root@localhost tomcat]# ls
apache-tomcat-9.0.16.tar.gz Dockerfile jdk-8u91-linux-x64.tar.gz
[root@localhost tomcat]# vim Dockerfile
FROM centos:7
RUN yum -y update
ADD jdk-8u91-linux-x64.tar.gz /usr/local/
WORKDIR /usr/local/
RUN mv jdk1.8.0_91 /usr/local/java
ENV JAVA_HOME /usr/local/java
ENV JRE_HOME ${JAVA_HOME}/jre
ENV CLASSPATH .:${JAVA_HOME}/lib:${JRE_HOME}/lib
ENV PATH $JAVA_HOME/bin:$PATH
ADD apache-tomcat-9.0.16.tar.gz /usr/local
RUN mv apache-tomcat-9.0.16 /usr/local/tomcat
EXPOSE 8080
ENTRYPOINT /usr/local/tomcat/bin/startup.sh && tail -f /usr/local/tomcat/logs/catalina.out
[root@localhost tomcat]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
tomcat new b8368375f32b 12 seconds ago 1.21GB
<none> <none> 80a6d110b4f3 3 minutes ago 815MB
nginx test b8beee210c3a 9 minutes ago 544MB
nginx new 8539f950fcb7 20 minutes ago 544MB
centos 7 8652b9f0cb4c 10 months ago 204MB
[root@localhost tomcat]# docker run -d -P tomcat:new
618ce8fc249eabf0568518e7d81b3e8deb7aa9e2117d8753f7134f985fd29df7
[root@localhost tomcat]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
618ce8fc249e tomcat:new "/bin/sh -c '/usr/lo..." 4 seconds ago Up 3 seconds 0.0.0.0:49154->8080/tcp, :::49154->8080/tcp adoring_germain
04d9a4656392 80a6d110b4f3 "/bin/sh -c 'mv jdk1..." 4 minutes ago Exited (1) 4 minutes ago naughty_lichterman
ce3b9cc6ce37 nginx:new "/bin/sh -c nginx" 21 minutes ago Up 21 minutes 0.0.0.0:49153->80/tcp, :::49153->80/tcp heuristic_ritchie
summary
Generally, the mirror you make will always be very large, so how can you optimize it?
1. Drop commands that do not require output into/dev/nulll
2. Reduce RUN build
3. Multi-phase build (use the FROM command to generate multiple mirrors, using the specified mirror as the underlying mirror environment for other mirrors)