DockerFile Introduction
DockerFile Docker is used to build the image file, the pace is a series of commands and configuration parameters
Search on docker hub and view the centos DockerFile as follows:
DockerFile Basics
1, each instruction must be reserved words in uppercase and subtitles to follow behind at least one parameter
2, the instruction execution in top-down order
3, # denotes a comment
4, each instruction will create a new image layer, and mirror commit
DockerFile build process
1, docker run from a container base image
2, and to execute an instruction to modify the container
3, a similar operation is performed docker commit to submit a new image layer
4, docker again based mirroring run just submitted a new container
5, the next instruction executed dockerfile until completion of all instructions execute
Case:
You can refer to [Application] Docker containers data volume (D) , a data volume of the container to add two ways: using DockerFile add, compare build process of this procedure DockerFIle
DockerFile reserved words
1、FROM
Base image, a new image is based on the current mirror
2、MAINTAINER
Mirror defenders name and e-mail address
3、RUN
Command need to run container building
4、EXPOSE
External exposure to a current container port
5、WORKDIR
After re-create the specified container terminal logged in the default working directory
6、ENV
To set the environment variables in the construction process of the mirror
7、ADD
The host file in the directory image and copied into the ADD command processing URL and automatically extract the tar archive
8、COPY
Similarly file ADD, to the mirror copy of the document directory, the directory from the building context <source path> / directory to <destination path> in the new position of the mirror layer
Use a: COPY src dest
用法二：COPY ["src", "dest"]
9、VOLUME
Data volume container, for persistent data storage and work
10、CMD
Specify a command to run on startup container
In Dockerfile can have multiple CMD command, but only the last one will work, CMD parameter will be replaced after the docker run
11、ENTRYPOINT
Specify a command to run on startup container
ENTRYPOINT purpose and CMD, it is in the specified container and start the program parameters
12、ONBUILD
When building an inherited Dockerfile run the command, the father of the mirror is triggered after the quilt in his father's image of onbuild
A case -Base mirror (scratch)
Docker Hub 99% of the image are required by installing and configuring software in the mirror base out construct
1 FROM scratch
Case B - Custom Mirror mycentos
1, write DockerFile file
1 # centos mirror base image 2 the FROM centos . 3 . 4 # image defenders name and email address . 5 the MAINTAINER on H__D < H__D @ 163.com > . 6 . 7 # environment variables . 8 ENV MYPATH / usr / local . 9 10 # working directory . 11 the WORKDIR $ MYPATH 12 is 13 is run Setup command vim construct # 14 the rUN -Y yum the install vim 15 16 when run # build-mounted Tools NET . 17 the rUN yum the install -Y-NET Tools 18 is . 19 # exposed outside the current container port 20 is eXPOSE 80 21 is 22 is run command to start # 23 CMD echo $MYPATH 24 25 CMD echo "build success .............." 26 27 CMD /bin/bash
2, building
Format: Docker Build a new mirror -t name: TAG.
命令：docker build -f dockerfile2 -t test/mycentos:1.2 .
3, run
Format: Docker RUN -it new image name: TAG
Command: Docker Expediting IT Test RUN / mycentos: 1.2
4, mirroring the change history list
Format: Docker History mirror name: TAG
Command: Docker History Test / mycentos: 1.2
Case C -CMD / ENTRYPOINT Mirror Case
When a container is specified command starts to run
1, CMD: Dockerfile can have multiple CMD command, but only the last one will work, CMD parameter will be replaced after the docker run
1) Create a dockerfile4, as follows:
1 # centos mirror base image 2 the FROM centos . 3 . 4 # running start command . 5 the CMD [ "/ bin / echo", "the Hello"]
2) By dockerfile4, constructing test / mycmd mirroring
命令：docker build -f dockerfile4 -t test/mycmd .
3) Testing
Command: Docker -it the Test RUN / mycmd
命令：docker run -it test/mycmd /bin/echo "ABC"
2, ENTRYPOINT: you can append parameters
1) Create a dockerfile3, as follows:
1 # centos mirror base image 2 the FROM centos . 3 . 4 Run # command starts . 5 EntryPoint [ "/ bin / echo", "the Hello"] . 6 . 7 # Docker Expediting IT RUN [Image] After running output . 8 # Hello World . 9 # Docker run -it [image] "command" output after running 10 # Hello command line
2) By dockerfile3, constructing test / myentrypoint mirroring
命令：docker build -f dockerfile3 -t test/myentrypoint .
3) Testing
命令：docker run -it test/myentrypoint
命令：docker run -it test/myentrypoint "ABC"
D Case -ONBUILD
ONBUILD: Run command when building an inherited Dockerfile, the father of the mirror is triggered after the quilt in his father's image of onbuild
1, a new dockerfile5 file, as follows:
1 # centos basis Mirror Mirror 2 the FROM centos 3 4 # mirrored quilt trigger 5 ONBUILD RUN echo "now, Build Action IS the ok .............." 6 7 Run command to start # 8 CMD [ "/ bin / bash"]
2, by constructing dockerfile5 test / mycentos: 1.5 mirroring
命令：docker build -f dockerfile5 -t test/mycentos:1.5 .
3, a new file dockerfile6, the base image is a test / mycentos: 1.5, as follows:
1 # centos mirror base image 2 the FROM Test / mycentos: for 1.5 . 3 . 4 Run # command starts . 5 the CMD [ "/ bin / the bash"]
4, constructed by dockerfile6 test / mycentos: 1.6 mirroring
命令：docker build -f dockerfile6 -t test/mycentos:1.6 .
Through observation, we can see the role of ONBUILD command
E cases - custom images Tomcat9