Kubernetes: Docker 基础

TAGS: Kubernetes

Docker 是什么

Docker：它是一个开源的软件项目，在Linux操作系统上，docker提供了一个额外的软件抽象层及操作系统层虚拟化的自动管理机制。

docker 设计理念及发展历程

物理机：

安装系统
依赖环境
- Java – jdk jre
- NodeJS – Node
- PHP – PHP
应用程序
加一个物理机—> 提高并发量

虚拟机：

KVM Xen

把一个物理机虚拟机虚拟成多个机器
把依赖环境打成一个系统的模板

容器化：

Docker

镜像基础
- 依赖环境的镜像
  - Java – Java基础的基础镜像
  - PHP – PHP基础的基础镜像
- 根据基础镜像 – 放入自己的代码或者包
  - 生产一个新镜像
  - 程序镜像
- 镜像 – 按层存储
  - A – Java JDK1.8
    - a.jar
  - B – Java -> JDK1.8
    - b.jar

2.启动时间特别，秒级启动

容器：把自己的应用程序，根据某个依赖的基础镜像，生成一个应用程序镜像。应用程序镜像，可以运行在任何部署了Docker环境的机器上。

Docker基本命令

docker version
docker info
docker search
docker pull
docker push
docker run
docker logs
docker ps
docker exec

docker cp
docker rmi
docker rm
docker tag
docker images
docker stop
docker build
docker history
docker commit

# 查看Docker版本
[root@k8s-master01 ~]# docker version

Client: Docker Engine - Community
 Version:           19.03.4
 API version:       1.40
 Go version:        go1.12.10
 Git commit:        9013bf583a
 Built:             Fri Oct 18 15:52:22 2019
 OS/Arch:           linux/amd64
 Experimental:      false

Server: Docker Engine - Community
 Engine:
  Version:          19.03.4
  API version:      1.40 (minimum version 1.12)
  Go version:       go1.12.10
  Git commit:       9013bf583a
  Built:            Fri Oct 18 15:50:54 2019
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          1.2.6
  GitCommit:        894b81a4b802e4eb2a91d1ce216b8817763c29fb
 runc:
  Version:          1.0.0-rc8
  GitCommit:        425e105d5a03fabd737a126ad93d62a9eeede87f
 docker-init:
  Version:          0.18.0
  GitCommit:        fec3683

Docker详细信息
[root@k8s-master01 ~]# docker info

Client:
 Debug Mode: false

Server:
 Containers: 8
  Running: 4
  Paused: 0
  Stopped: 4
 Images: 8
 Server Version: 19.03.4
 Storage Driver: overlay2
        # aufs、overlay brtfs
  Backing Filesystem: xfs
  Supports d_type: true
  Native Overlay Diff: true
 Logging Driver: json-file
# json-file: 存在本地
 Cgroup Driver: cgroupfs
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
 Swarm: inactive
 Runtimes: runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 894b81a4b802e4eb2a91d1ce216b8817763c29fb
 runc version: 425e105d5a03fabd737a126ad93d62a9eeede87f
 init version: fec3683
 Security Options:
  seccomp
   Profile: default
 Kernel Version: 4.18.0-80.el8.x86_64
 Operating System: CentOS Linux 8 (Core)
 OSType: linux
 Architecture: x86_64
 CPUs: 2
 Total Memory: 1.764GiB
 Name: k8s-master01
 ID: PRWL:PVRE:U7JQ:LNM6:SNLN:4QDV:URQA:MWQF:XXCE:VOT3:53GL:ECC6
 Docker Root Dir: /var/lib/docker
# 可以更改的，ssd的硬盘。最好使用一个单独的磁盘进行挂载
 Debug Mode: false
 Registry: https://index.docker.io/v1/
 Labels:
 Experimental: false
 Insecure Registries:
  127.0.0.0/8
 Live Restore Enabled: false



搜索镜像：
[root@k8s-master01 ~]# docker search centos
NAME                               DESCRIPTION                                     STARS               OFFICIAL            AUTOMATED
centos                             The official build of CentOS.                   6054                [OK]                
ansible/centos7-ansible            Ansible on Centos7                              130                                     [OK]
consol/centos-xfce-vnc             Centos container with "headless" VNC session…   116                                     [OK]
jdeathe/centos-ssh                 OpenSSH / Supervisor / EPEL/IUS/SCL Repos - …   114                                     [OK]
centos/systemd                     systemd enabled base container.                 84                                      [OK]
centos/mysql-57-centos7            MySQL 5.7 SQL database server                   77                                      
imagine10255/centos6-lnmp-php56    centos6-lnmp-php56                              58                                      [OK]
tutum/centos                       Simple CentOS docker image with SSH access      47                                      
centos/postgresql-96-centos7       PostgreSQL is an advanced Object-Relational …   45                                      
kinogmt/centos-ssh                 CentOS with SSH                                 29                                      [OK]
pivotaldata/centos-gpdb-dev        CentOS image for GPDB development. Tag names…   12                                      
guyton/centos6                     From official centos6 container with full up…   10                                      [OK]
drecom/centos-ruby                 centos ruby                                     6                                       [OK]
centos/tools                       Docker image that has systems administration…   6                                       [OK]
pivotaldata/centos                 Base centos, freshened up a little with a Do…   4                                       
pivotaldata/centos-gcc-toolchain   CentOS with a toolchain, but unaffiliated wi…   3                                       
pivotaldata/centos-mingw           Using the mingw toolchain to cross-compile t…   3                                       
darksheer/centos                   Base Centos Image -- Updated hourly             3                                       [OK]
miko2u/centos6                     CentOS6 日本語環境                                   2                                       [OK]
blacklabelops/centos               CentOS Base Image! Built and Updates Daily!     1                                       [OK]
mcnaughton/centos-base             centos base image                               1                                       [OK]
indigo/centos-maven                Vanilla CentOS 7 with Oracle Java Developmen…   1                                       [OK]
pivotaldata/centos6.8-dev          CentosOS 6.8 image for GPDB development         0                                       
smartentry/centos                  centos with smartentry                          0                                       [OK]
pivotaldata/centos7-dev            CentosOS 7 image for GPDB development           0                                       
[root@k8s-master01 ~]# docker search nginx
NAME                               DESCRIPTION                                     STARS               OFFICIAL            AUTOMATED
nginx                              Official build of Nginx.                        13358               [OK]



Docker拉取镜像：
拉取一个镜像到本地：
[root@k8s-master01 ~]# docker pull alpine:latest
latest: Pulling from library/alpine
df20fa9351a1: Already exists 
Digest: sha256:185518070891758909c9f839cf4ca393ee977ac378609f700f60a771a2dfe321
Status: Downloaded newer image for alpine:latest
docker.io/library/alpine:latest

push 推送镜像

Docker run：启动一个镜像
1.前台启动
a)[root@k8s-master01 ~]# docker run -ti centos:8 bash
b)[root@55eb31fec62e /]# whoami 
c)root
2.后台启动  
-d 后台启动一个镜像

查看容器日志：docker logs -f

dockerfile

FROM：继承基础镜像
MAINTAINER：镜像制作作者信息
RUN：用来执行shell命令
EXPOSE：暴露端口号
CMD：启动容器默认执行的命令
ENTRYPOINT：启动容器真正执行的命令
VOLUME：创建挂载点
ENV：配置环境变量
ADD：复制文件到容器
COPY：复制文件到容器
WORKDIR：设置容器的工作目录
USER：容器使用的用户


CMD和ENTRYPIOINT 必须要有一个
CMD可以被覆盖，如果有ENTRYPIOINT的话，CMD就是ENTRYPIOINT的参数。

ENTRYPIOINT – 》 COMMAND
CMD –》 arg

FROM centos:8
LABEL maintainer="test dockerfile"
LABEL test=dockerfile
RUN useradd dot
RUN mkdir /opt/dot
CMD [ "sh", "-c", "echo 1"]
#RUN useradd dot && /opt/dot




FROM centos:8

LABEL maintainer="test dockerfile"
LABEL test=dockerfile

ENV test_env1 env1
ENV test_env2 env2
RUN useradd dot
RUN mkdir /opt/dot

#ENTRYPOINT ["echo"]
ENV env1=test1 env2=test2

ADD ./index.tar.gz /opt/
COPY ./index.tar.gz /opt/dot/
WORKDIR /opt/dot
USER 1000
CMD pwd ; ls
#RUN useradd dot && /opt/dot

制作镜像

制作小镜像：

一定不要使用centos镜像
Alpine，busybox，scratch(空镜像)，Debian
Glibc： node:slim python:slim net

使用多阶段构建：编译操作和生成最终镜像的操作

# build step
FROM golang:1.14.4-alpine as builder
WORKDIR /opt

COPY main.go /opt

RUN go build /opt/main.go 

CMD "./main"

# create real app image

FROM alpine:3.8

COPY --from=builder /opt/main /

CMD "./opt/main"



FROM php:7.1.22-fpm-alpine

RUN apk add --no-cache binutils freetype libpng libjpeg-turbo freetype-dev libpng-dev libjpeg-turbo-dev libc6-compat libxml2 libxml2-dev libmcrypt libmcrypt-dev     libc-dev   icu-dev gettext-dev  openssl-dev bzip2-dev

RUN docker-php-ext-install pdo pdo_mysql mcrypt zip gd pcntl opcache bcmath 
#RUN docker-php-ext-install gettext 
RUN docker-php-ext-install mysqli 
#RUN apk add --no-cache php7-sysvsem php7-pdo_dblib  php7-sockets php-soap php7-xmlrpc
##RUN apk add --no-cache php7-sysvsem php7-pdo_dblib  php7-sockets php-soap php7-xmlrpc
##RUN apk add --no-cache freetds-dev
##RUN docker-php-ext-install pdo_dblib 
#RUN docker-php-ext-install soap 
#RUN docker-php-ext-install sockets
#RUN docker-php-ext-install sysvsem 
#RUN docker-php-ext-install xmlrpc
#RUN apk add --no-cache freetds-dev
#RUN docker-php-ext-install pdo_dblib
#RUN docker-php-ext-configure gd --with-freetype-dir=/usr/include/ --with-jpeg-dir=/usr/include/
#RUN docker-php-ext-install -j$(nproc) gd
#FROM php:7.1.22-fpm-alpine

#COPY --from=0 /usr/local/lib/php/extensions/no-debug-non-zts-20160303 /usr/local/lib/php/extensions/no-debug-non-zts-20160303

#RUN apk add --no-cache freetds-dev php7-sysvsem php7-pdo_dblib  php7-sockets php-soap php7-xmlrpc binutils freetype libpng libjpeg-turbo freetype-dev libpng-dev libjpeg-turbo-dev libc6-compat libxml2 libxml2-dev libmcrypt libmcrypt-dev     libc-dev   icu-dev gettext-dev  openssl-dev bzip2-dev && cd /usr/local/lib/php/extensions/no-debug-non-zts-20160303 && docker-php-ext-enable *.so  && rm -rf /var/cache/apk/*