Shulou(Shulou.com)06/02 Report--

This article introduces the relevant knowledge of "introduction and simple use of docker". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

What is 1.docker?

Docker is a containerized platform that provides application packaging, deployment and running applications.

Application-> docker engine-> physical hardware

The application is no longer directly oriented to the underlying resources, but to the middle-tier docker engine.

Docker engine includes: docker server, rest api, docker client.

Through this structure, users can easily manage multiple servers through the client.

2. Container and Mirror

Image: an image is a read-only file that provides complete software and hardware resources for running the program.

Containers: containers are mirrored instances, which are created by docker. Containers are isolated from each other.

3. Docker execution process

Docker pull redis

Client-> Docker Daemon checks the redis image, if the local image does not exist-> get the image from the remote central repository

Docker run redis

Client-> Docker Daemon redis image exists-> create a container, and the redis exposes the service to the outside, which is a complete centos system for the inner container.

4. Common command

Docker pull image name-extract the image from the remote repository

Docker images-View locally downloaded images

Docker run image name-create a container and launch the application

Docker ps-View running images

Docker rm Container id-Delete a container

Docker rmi image name:-Delete image

5. Rapid deployment of tomcatdocker run-p 8000 tomcat hub.docker.com# 8080-d tomcat:latest# deploy the latest version of tomcat hub.docker.com# port mapping in the container-p 8000 tomcat hub.docker.com# 8080 8000 as the host port, 8080 as the tomcat port #-d background running 6. Internal structure of container

Take tomcat container as an example: including tomcat, jdk, mini version of linux system

7. Execute commands in a container

Docker exec-it [Interactive Command execution] Container id/ Container name Command

Docker exec-it cc0ebcaaef7a / bin/bash enters the container bash

8. Write DockerfileFROM tomcat:latestMAINTAINER yz.comWORKDIR / usr/local/tomcat/webappsADD docker-web. / docker-web# to package docker build-t yz.com/mywebapp.0.1. # run the container docker run-p 8001 usr/local/tomcat/webappsADD docker-web 8080 yz.com/mywebapp.0.1# to visit http://localhost:8001/docker-web/index.htmlFROM java:8MAINTAINER yz.comWORKDIR / usr/local/apps/jarsADD xx.jar. / xx.jarENTRYPOINT ["nohup", "java", "- jar" "xx.jar", "&"] 9. Mirror layered Sending build context to Docker daemon 3.584kBStep 1 usr/local/tomcat/webapps 4: FROM tomcat:latest-> 2ae23eb477aaStep 2 usr/local/tomcat/webapps 4: MAINTAINER yz.com-- > Using cache-- > b0efa3602df6Step 3 usr/local/tomcat/webapps 4: WORKDIR / usr/local/tomcat/webapps-- > Using cache-- > bf93f5630ca1Step 4max 4: ADD docker-web. / docker-web-- > Using cache-- > 603504ab383fSuccessfully built 603504ab383fSuccessfully tagged dmall.com/inventory-app:0.2

Each step produces a temporary mirror, and-- > Using cache means that the cache is used for the steps previously performed.

10.Dockerfile basic command FROM centos # make reference image (based on centos) FROM scratch # do not rely on any image # try to use the official Base Image MAINTAINER yz.comLABEL version = "1.0" LABEL description = "image description" WORKDIR / usr/local/xx # work path, use absolute path as far as possible, directories will be created automatically And cd to the current directory ADD xx.jar. / # copy the xx.jar file to the working path ADD test.tar.gz / # add to the root directory and extract ENV JAVA_HOME / usr/local/java8 # to set the environment constant 11. Dockerfile run instruction # at different times. RUN xx # execute command on build build time ENTRYPOINT xx # execute command on container startup CMD xx # execute default command or parameter 11.1 RUN-run RUN yum install-y vim # shell command format RUN ["yum", "install", "- y", "vim"] # Exec command format Shell operation

When executing with shell, the current shell is the parent process, generating a child shell process that executes the script in the child shell.

When the script is finished, exit the child shell and return to the current shell.

Exec operation mode

Using the Exec method, the current process is replaced with the Exec process, and the pid is left unchanged.

After execution, exit directly, and will not return to the previous process environment.

11.2 ENTRYPOINT-start command

The ENTRYPOINT (entry point) is used to execute commands when the container starts.

Only the last ENTRYPOINT in the Dockerfile will be executed.

Exec format is recommended

ENTRYPOINT will definitely execute.

11.3 CMD-default execution of command

Commands used by CMD to set default execution

If more than one CMD appears in the Dockerfile, only the last one is executed.

If an instruction is attached when the container starts, the CMD is ignored.

It is recommended to use Exec format to execute commands

CMD is not necessarily executed, for example, docker run yz.com/test_cmd:0.1 ls is followed by a command that replaces the cmd command.

12. Docker Custom build redis Image # download redis source code wget http://download.redis.io/releases/redis-5.0.9.tar.gz

Write Dockerfile files

FROM centosRUN ["yum", "install", "- y", "gcc", "gcc-c++", "net-tools", "make"] WORKDIR / usr/localADD redis-5.0.9.tar.gz. / WORKDIR / usr/local/redis-5.0.9/srcRUN make & & make installWORKDIR / usr/local/redis-5.0.9/ADD redis-6379.conf. / EXPOSE 6379CMD ["redis-server" "redis-6379.conf"] # build redis image docker build-t xx.com/redis-6379. / # run redis container docker run-p 6379 xx.com/redis-6379# to start and close container docker start containerIddocker stop containerId13. Communication between docker

Because the container allocates a new ip every time it starts, how can you communicate effectively between containers?

13.1 one-way communication # create redis6379docker run-p 6379centos link redis6379docker run-d-name redis6379 redis# create centos link redis6379docker run-- name centos-- link redis6379-it centos / bin/bash# test can successfully ping ping redis637964 bytes from redis6379 (172.17.0.4): icmp_seq=1 ttl=64 time=0.061 ms13.2 two-way communication based on Bridge # View docker network docker network lsNETWORK ID NAME DRIVER SCOPE6b60f6c242a3 bridge bridge localb51d649d7adb host host local6c0f31888ef7 none null local# creates a new bridge docker network create-d bridge my-bridge# to view the network docker network lsNETWORK ID NAME DRIVER SCOPE6b60f6c242a3 bridge bridge Localb51d649d7adb host host local68aa95b088c3 my-bridge bridge local6c0f31888ef7 none null local# opens two new centos containers docker run-dit-- name os1 centosdocker run-dit-- name os2 centos# binds to my-bridgedocker network connect my-bridge os1docker network connect my-bridge os2# and enters os1 ping os2docker exec- It os1 bashping os2PING os2 (172.18.0.3) 56 (84) bytes of data.64 bytes from os2.my-bridge (172.18.0.3): icmp_seq=1 ttl=64 time=0.032 ms# enters os2 ping os1ping os1PING os1 (172.18.0.2) 56 (84) bytes of data.64 bytes from os1.my-bridge (172.18.0.2): icmp_seq=1 ttl=64 time=0.032 ms14. Data sharing between containers

The host mounts a volume, and multiple containers share the data of the same volume.

# create a shared container docker create by-v mounting the host directory docker run-- name os3-dit-v / root:/mnt/root centos bashdocker exec-it os3 bashls / mnt/root#-name webapp-v / usr/local/tomcat/webapps:/usr/local/tomcat/webapps tomcat/ bin/true# shared container mount point docker run-- volumes-from webapp-- name tomcat2-p 18002Visual8080-d tomcat# accesses the host port 18002 and finds it effective

Using this feature, static resources on the host, such as page files, can be shared to the container's resource directory.

This is the end of the introduction and simple use of docker. Thank you for your reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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