| 知乎专栏 ｜ 多维度架构 |
为什么要自己创建镜像呢？ 因为官方提供的镜像无法满足我们的需求，例如 nginx 镜像你会发现 ps, top 等等很多命令缺失。
需求基于centos7镜像创建nginx stable最新版本镜像
############################################################ # Dockerfile to build Nginx container # Based on centos7 ############################################################ FROM centos:latest MAINTAINER Netkiller <netkiller@msn.com> # Install EPEL RUN yum install -y epel-release && yum clean all # Update RPM Packages RUN yum -y update # Install Nginx RUN rpm -ivh http://nginx.org/packages/centos/7/noarch/RPMS/nginx-release-centos-7-0.el7.ngx.noarch.rpm RUN yum install -y nginx RUN yum clean all # forward request and error logs to docker log collector RUN ln -sf /dev/stdout /var/log/nginx/access.log RUN ln -sf /dev/stderr /var/log/nginx/error.log # be backwards compatible with pre-official images #RUN ln -sf ../share/nginx /usr/local/nginx # prepare container # add startup script #ADD startup.sh /startup.sh #RUN chmod 755 /startup.sh VOLUME ["/etc/nginx"] VOLUME ["/usr/share/nginx/html"] VOLUME ["/var/www"] EXPOSE 80 443 CMD ["nginx", "-g", "daemon off;"]
# docker build -t "centos:nginx" . Sending build context to Docker daemon 3.072 kB Step 1/14 : FROM centos:latest ---> 3bee3060bfc8 Step 2/14 : MAINTAINER Netkiller <netkiller@msn.com> ---> Using cache ---> 8f351964d568 Step 3/14 : RUN yum install -y epel-release && yum clean all ---> Using cache ---> bf86eff77ff3 Step 4/14 : RUN yum -y update ---> Using cache ---> 4915172ac4f3 Step 5/14 : RUN rpm -ivh http://nginx.org/packages/centos/7/noarch/RPMS/nginx-release-centos-7-0.el7.ngx.noarch.rpm ---> Using cache ---> 4a919bd141c9 Step 6/14 : RUN yum install -y nginx ---> Using cache ---> 2718221eab8c Step 7/14 : RUN yum clean all ---> Using cache ---> 62231a5f1d76 Step 8/14 : RUN ln -sf /dev/stdout /var/log/nginx/access.log ---> Using cache ---> 38be8f0cc782 Step 9/14 : RUN ln -sf /dev/stderr /var/log/nginx/error.log ---> Using cache ---> bbf3a468d24f Step 10/14 : VOLUME /etc/nginx ---> Using cache ---> 919292c7ce04 Step 11/14 : VOLUME /usr/share/nginx/html ---> Using cache ---> c2aeb8ed3c1c Step 12/14 : VOLUME /var/www ---> Using cache ---> 31849cb8a9d0 Step 13/14 : EXPOSE 80 443 ---> Using cache ---> 0e3d3b4a215b Step 14/14 : CMD nginx -g daemon off; ---> Using cache ---> d5f21e409690 Successfully built d5f21e409690
查看镜像
# docker image ls REPOSITORY TAG IMAGE ID CREATED SIZE centos nginx d5f21e409690 4 minutes ago 364 MB centos latest 3bee3060bfc8 2 days ago 193 MB nginx latest 958a7ae9e569 8 days ago 109 MB redis latest a858478874d1 2 weeks ago 184 MB
# docker run --name my-centos-nginx -d centos:nginx ecf342ddd66d1d5f3d28c583ec852c05903ef4813fcb75295c907a6b578dea3d # docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES ecf342ddd66d centos:nginx "nginx -g 'daemon ..." 23 seconds ago Up 23 seconds 80/tcp, 443/tcp my-centos-nginx 0df3b275bb03 nginx "nginx -g 'daemon ..." 6 hours ago Up 6 hours 80/tcp my-nginx 1c4540d8617f redis "docker-entrypoint..." 2 days ago Up 2 days 0.0.0.0:6379->6379/tcp my-redis
[root@netkiller]~/docker/nginx# docker exec -it my-centos-nginx /bin/bash
[root@netkiller-docker /]# ps ax
PID TTY STAT TIME COMMAND
1 ? Ss 0:00 nginx: master process nginx -g daemon off;
7 ? S 0:00 nginx: worker process
8 ? Ss 0:00 /bin/bash
22 ? R+ 0:00 ps ax
[root@netkiller-docker /]# curl http://localhost
<!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>
# docker commit my-centos-nginx netkiller/centos:nginx sha256:9ea1851b1c9f04aa3168977f666337223d09e20983f7a2c2328e15132a03d224
# docker push netkiller/centos:nginx The push refers to a repository [docker.io/netkiller/centos] 16916856eaaa: Pushed 6172d61b45f1: Pushed db323af550f0: Pushed 232df2cfd38f: Pushed c247a550215b: Pushed 3b5451d7989c: Pushed e3a6f1af6a7a: Pushed 9e3cea652b37: Pushed dc1e2dcdc7b6: Mounted from library/centos nginx: digest: sha256:ad9bd1ae3a3e17dac70f32afc14baf90932949d3eaa8bebbe907726aca3ea336 size: 2205
工作中我们常常发现官方镜像裁剪的面目全非，里面缺失很多常用工具，这种情况给我们工作带来诸多不便。
ps,top 等系统工具
apt update -y && apt install -y procps
ip, ss
apt install -y iproute2
ifconfig, netstat
apt install -y net-tools
跨容器拷贝
FROM demo/test:latest as netkiller MAINTAINER Netkiller <netkiller@msn.com> RUN mkdir /www COPY some/path/to/ /www/ FROM nginx:1.13-alpine RUN rm -rf /usr/share/nginx/html/* COPY --from=netkiller /www/ /usr/share/nginx/html/
--from 参数
# Install the base requirements for the app.
# This stage is to support development.
FROM python:alpine AS base
WORKDIR /app
COPY requirements.txt .
RUN pip install -r requirements.txt
# Run tests to validate app
FROM node:12-alpine AS app-base
WORKDIR /app
COPY app/package.json app/yarn.lock ./
RUN yarn install
COPY app/spec ./spec
COPY app/src ./src
RUN yarn test
# Clear out the node_modules and create the zip
FROM app-base AS app-zip-creator
RUN rm -rf node_modules && \
apk add zip && \
zip -r /app.zip /app
# Dev-ready container - actual files will be mounted in
FROM base AS dev
CMD ["mkdocs", "serve", "-a", "0.0.0.0:8000"]
# Do the actual build of the mkdocs site
FROM base AS build
COPY . .
RUN mkdocs build
# Extract the static content from the build
# and use a nginx image to serve the content
FROM nginx:alpine
COPY --from=app-zip-creator /app.zip /usr/share/nginx/html/assets/app.zip
COPY --from=build /app/site /usr/share/nginx/html
从命令行传递参数给容器
FROM ubuntu ENTRYPOINT [ "top", "-b" ]
运行下面的命令：
$ docker run --rm test1 -c
实际 Docker 内部
top -b -c
ENTRYPOINT 与 CMD 组合
FROM ubuntu ENTRYPOINT [ "top", "-b" ] CMD [ "-c" ]
ENTRYPOINT ["docker-entrypoint.sh"]
你不能写成
ENTRYPOINT docker-entrypoint.sh
ENTRYPOINT docker-entrypoint.sh 会使用 sh -c 执行
"/bin/sh -c /srv/docker-entrypoint.sh /srv/rocketmq/bin/mqnamesrv"
而我们需要的是
/srv/docker-entrypoint.sh /srv/rocketmq/bin/mqnamesrv
所以需要写成 ENTRYPOINT ["docker-entrypoint.sh"]