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Hello everyone, I'm Shanyue, this is my newly opened column: Front-end Deployment Series . Including Docker, CICD, etc., the outline diagram is as follows:
The sample code is open source and placed in Github to demonstrate how to deploy a real project online.
Front-end deployment series is being updated : 16/18
dockerIt makes application deployment more lightweight, portable, and scalable, and better environment isolation also avoids the huge embarrassment of inconsistency between the production environment and the test environment to a greater extent.
Due to the characteristics of dockerportability and portability, it has also greatly promoted the CI/CDdevelopment of .
the term
dockerThe architecture diagram is as follows
Several components can be seen from the figure
docker client: i.e.dockercommand line tooldocker host: host,docker daemonthe operating environment serverdocker daemon:dockerdaemon, interactsdocker clientwith via the command linedocker daemonimage: Image, which can be understood as the template of a container, through which multiple containers can be createdcontainer: The smallest operating system environment, which can containerize various services and applications, and is the running instance of the imageregistry: Mirror repository, stores a large number of images, can pull and push images from the mirror repository
install docker
Install docker/docker-compose locally, download docker through Docker Desktop , and double-click to install it.
If it is a personal server and it is centos, please refer to Install docker .
underlying principle
docker 底层使用了一些 linux 内核的特性，大概有 namespace，cgroups 和 ufs。
namespace
docker 使用 linux namespace 构建隔离的环境，它由以下 namespace 组成
pid: 隔离进程net: 隔离网络ipc: 隔离 IPCmnt: 隔离文件系统挂载uts: 隔离hostnameuser: 隔离uid/gid
control groups
也叫 cgroups，限制资源配额，比如某个容器只能使用 100M 内存
Union file systems
UnionFS 是一种分层、轻量级并且高性能的文件系统，支持对文件系统的修改作为一次提交来一层层的叠加。docker 的镜像与容器就是分层存储，可用的存储引擎有 aufs，overlay 等。
关于分层存储的详细内容可以查看官方文档 docker: About storage drivers
镜像
镜像是一份用来创造容器的配置文件，而容器可以视作最小型的一个操作系统。
docker 的镜像和容器都使用了 unionFS 做分层存储，镜像作为只读层是共享的，而容器在镜像之上附加了一层可写层，最大程度地减少了空间的浪费，详见下图
镜像仓库与拉取
大部分时候，我们不需要自己构建镜像，我们可以在官方镜像仓库拉取镜像
可以简单使用命令 docker pull 拉取镜像。拉取镜像后可以使用 docker inspect 查看镜像信息
# 加入拉取一个 node:alpine 的镜像
$ docker pull node:alpine
# 查看镜像信息
$ docker inspect node:alpine
# 列出所有镜像
$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
node alpine f20a6d8b6721 13 days ago 105MB
mongo latest 965553e202a4 2 weeks ago 363MB
centos latest 9f38484d220f 8 months ago 202MB
复制代码构建镜像与发布
但并不是所有的镜像都可以在镜像仓库中找到，另外我们也需要为我们自己的业务应用去构建镜像。
使用 docker build 构建镜像，docker build 会使用当前目录的 dockerfile 构建镜像，至于 dockerfile 的配置，参考下节。
-t 指定标签
# -t node-base:10: 镜像以及版本号
# .: 指当前路径
$ docker build -t node-base:10 .
复制代码当构建镜像成功后可以使用 docker push 推送到镜像仓库
Dockerfile
在使用 docker 部署自己应用时，往往需要自己构建镜像。docker 使用 Dockerfile 作为配置文件构建镜像，简单看一个 node 应用构建的 dockerfile
FROM node:alpine
ADD package.json package-lock.json /code/
WORKDIR /code
RUN npm install --production
ADD . /code
CMD npm start
复制代码FROM
基于一个旧有的镜像，格式如下
FROM <image> [AS <name>]
# 在多阶段构建时会用到
FROM <image>[:<tag>] [AS <name>]
复制代码ADD
把目录，或者 url 地址文件加入到镜像的文件系统中
ADD [--chown=<user>:<group>] <src>... <dest>
复制代码RUN
执行命令，由于 ufs 的文件系统，它会在当前镜像的顶层新增一层
RUN <command>
复制代码CMD
指定容器如何启动
一个 Dockerfile 中只允许有一个 CMD
# exec form, this is the preferred form
CMD ["executable","param1","param2"]
# as default parameters to ENTRYPOINT
CMD ["param1","param2"]
# shell form
CMD command param1 param2
复制代码容器
镜像与容器的关系，类似于代码与进程的关系。
docker run创建容器docker stop停止容器docker rm删除容器
创建容器
基于 nginx 镜像创建一个最简单的容器：启动一个最简单的 http 服务
使用 docker run 来启动容器，docker ps 查看容器启动状态
$ docker run -d --name nginx -p 8888:80 nginx:alpine
$ docker ps -l
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
404e88f0d90c nginx:alpine "nginx -g 'daemon of…" 4 minutes ago Up 4 minutes 0.0.0.0:8888->80/tcp nginx
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
复制代码其中:
-d: 启动一个daemon进程--name: 为容器指定名称-p host-port:container-port: 宿主机与容器端口映射，方便容器对外提供服务nginx:alpine: 基于该镜像创建容器
此时在宿主机使用 curl 测试容器提供的服务是否正常
$ curl localhost:8888
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
body {
width: 35em;
margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif;
}
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
复制代码那如果要进入容器环境中呢？使用 docker exec -it container-name 命令
$ docker exec -it nginx sh
/ #
/ #
/ #
复制代码容器管理
docker ps 列出所有容器
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
404e88f0d90c nginx:alpine "nginx -g 'daemon of…" 4 minutes ago Up 4 minutes 0.0.0.0:8888->80/tcp nginx
498e7d74fb4f nginx:alpine "nginx -g 'daemon of…" 7 minutes ago Up 7 minutes 80/tcp lucid_mirzakhani
2ce10556dc8f redis:4.0.6-alpine "docker-entrypoint.s…" 2 months ago Up 2 months 0.0.0.0:6379->6379/tcp apolloserverstarter_redis_1
复制代码docker port 查看容器端口映射
$ docker port nginx
80/tcp -> 0.0.0.0:8888
复制代码docker stats 查看容器资源占用
$ docker stats nginx
CONTAINER ID NAME CPU % MEM USAGE / LIMIT MEM % NET I/O BLOCK I/O PIDS
404e88f0d90c nginx 0.00% 1.395MiB / 1.796GiB 0.08% 632B / 1.27kB 0B / 0B 2
复制代码作业
- 初阶: 了解 docker 常见操作，如构建镜像、运行容器、进入容器执行命令
- 高阶: docker 原理，如何模拟 docker 隔离环境及限制资源
- Interview: Differences between Dockerfile, Image, and Container