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docker镜像编译与docker-compose部署与编排

news 来源：原创 2024/5/4 1:09:39

概念理解

虚拟机与docker。虚拟机用的是虚拟化的cpu，效率只有50%~60%。docker用的是物理cpu，效率趋近90% ~ 100%。docker进程隔离。

docker的命令很多，都记住不现实。–help可以查看具体的命令用途。如

docker --help

docker container --help

docker container ls --help

docker镜像与容器之间遵循写时复制的原则。一个镜像起了多个容器后，每个容器内修改的文件会保存，但不会影响原来的镜像。

删除某一个镜像前，由该镜像开启的容器必须先删掉。

案例

运行一个webserver的容器，由拉取的nginx镜像执行，后台开启服务，且开放80的端口

docker run --name webserver -d -p 80:80 nginx

访问http://localhost或127.0.0.1可以看到欢迎界面。

交互式进入这个webserver的容器

docker exec -it webserver bash

修改网页并退出

echo '<h1>Hello, Docker!</h1>' > /usr/share/nginx/html/index.html
exit

退出后可以查看webserver容器与nginx镜像的改动

docker diff webserver

然后提交

docker commit --message "modify information display" webserver nginx:v2

再显示镜像的时候可以看到TAG为v2的版本。

同一个端口可以被不同的镜像启动时映射吗？每个容器，或者进程会认为它可以用所有的资源，包括端口。就像进程面对的是虚拟内存一样。

Dockfile的定制

touch Dockerfile
vim Dockerfile ##输入以下内容
From nginx
RUN echo "<h1>Hello, Master's Docker! nginx-v3</h1>" > /usr/share/nginx/html/index.html

这里单引号会报错，双引号才能编译成功。生成镜像

docker build -t nginx:v3

通过docker images 可以查看到生成的镜像。

哪个命令可以查看到该镜像是基于哪个基础镜像生成的？

更复杂一点的Dockerfile

# this is dockerfile for nginx
# base image
FROM ubuntu:16.04

ADD nginx-1.13.7.tar.gz /usr/local/src/
ADD pcre-8.41.tar.gz /usr/local/src/
ADD zlib-1.2.11.tar.gz /usr/local/src/
ADD openssl-1.1.0g.tar.gz /usr/local/src/
#ADD sources.list /etc/apt/sources.list
RUN apt-get update
RUN apt-get install build-essential -y
WORKDIR /usr/local/src/nginx-1.13.7
RUN ./configure --prefix=/usr/local/nginx --with-http_realip_module --with-http_addition_module --with-http_gzip_static_module --with-http_secure_link_module --with-http_stub_status_module --with-stream --with-pcre=/usr/local/src/pcre-8.41 --with-zlib=/usr/local/src/zlib-1.2.11 --with-openssl=/usr/local/src/openssl-1.1.0g && make && make install

RUN echo "daemon off;" >> /usr/local/nginx/conf/nginx.conf

# RUN echo '<h1>Hello, Nginx-v4 Docker!</h1>' > /usr/local/src/nginx-1.13.7/html/index.html
RUN echo '<h1>Hello, Nginx-v4 Docker!</h1>' > /usr/local/nginx/html/index.html

EXPOSE 80

CMD ["/usr/local/nginx/sbin/nginx", "-c", "/usr/local/nginx/conf/nginx.conf"]

使用tree .查看目录下面的结构为

.
├── Dockerfile
├── nginx-1.13.7.tar.gz
├── openssl-1.1.0g.tar.gz
├── pcre-8.41.tar.gz
└── zlib-1.2.11.tar.gz

0 directories, 5 files

编译

docker build -t nginx:v4

由于编译过程中用的源是官网的源，很耗时间，因此将本机用的阿里源文件拷进容器。

  1 #  /etc/apt/source.list 阿里源
  2 deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
  3 deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
  4 deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
  5 deb http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
  6 deb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
  7 deb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
  8 deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
  9 deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
 10 deb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
 11 deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse

改变该文件的所有者chown和所属组chgrp

sudo cp /etc/apt/source.list .
sudo chown master source.list
sudo chgrp master source.list

重新编译，可生成v4镜像

Successfully built b0e7b7b6bfdc
Successfully tagged nginx:v4
master@qiu-k8s-m:~/nginx-v4$ docker images
REPOSITORY   TAG       IMAGE ID       CREATED          SIZE
nginx        v4        b0e7b7b6bfdc   12 seconds ago   420MB
nginx        v3        20f88cf0a372   10 hours ago     141MB
nginx        v2        8b9a697e12b4   21 hours ago     141MB
ubuntu       latest    2dc39ba059dc   3 weeks ago      77.8MB
nginx        latest    605c77e624dd   8 months ago     141MB
ubuntu       18.04     5a214d77f5d7   11 months ago    63.1MB
ubuntu       16.04     b6f507652425   13 months ago    135MB

运行该镜像生成一个容器实例

docker run --name web4 -d -p 83:80 nginx:v4

通过浏览器查看83端口，可以证实nginx在正常运行。

Docker Compose编排

它允许用户通过一个单独的 docker-compose.yml 模板文件（YAML 格式）来定义一组相关联的应用容器为一个项目。k8s出来之后docker compose的方式就不流行了。k8s比较重，学习成本高。compose可以一次性启动不同的服务，如redis, nginx，msg_server用compose一次性启动。k8s不仅可以启动多台机器的多种服务，还支持注册发现机制，心跳机制。且k8s的组网更复杂，如果没有linux内核知识比较难理解。

compose 实操

安装docker-compose

sudo apt-get install docker-compose

安装完后发现docker 不能用了，键入docker ps，出现

Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

错误的意思是，无法连接docker守护进程，docker守护进程是否在运行？运行服务会也报错

master@qiu-k8s-m:~$ sudo systemctl start docker.service
Job for docker.service failed because the control process exited with error code.
See "systemctl status docker.service" and "journalctl -xe" for details.

接着查看docker服务状态

master@qiu-k8s-m:~$ sudo systemctl status docker.service 
● docker.service - LSB: Create lightweight, portable, self-sufficient containers.
   Loaded: loaded (/etc/init.d/docker; generated)
   Active: failed (Result: exit-code) since Sun 2022-09-25 21:48:22 CST; 2min 46s ago
     Docs: man:systemd-sysv-generator(8)
  Process: 43015 ExecStart=/etc/init.d/docker start (code=exited, status=1/FAILURE)
 Main PID: 1074 (code=exited, status=0/SUCCESS)

Sep 25 21:48:22 qiu-k8s-m systemd[1]: Starting LSB: Create lightweight, portable, self-sufficient containers....
Sep 25 21:48:22 qiu-k8s-m docker[43015]:  * /usr/bin/dockerd not present or not executable
Sep 25 21:48:22 qiu-k8s-m systemd[1]: docker.service: Control process exited, code=exited status=1
Sep 25 21:48:22 qiu-k8s-m systemd[1]: docker.service: Failed with result 'exit-code'.
Sep 25 21:48:22 qiu-k8s-m systemd[1]: Failed to start LSB: Create lightweight, portable, self-sufficient containers
lines 1-12/12 (END)

那么找到报错的关键信息，是上面 * /usr/bin/dockerd not present or not executable这一行。去/usr/bin/目录下面确实找不到dockerd文件，而/etc/init.d/docker文件里面确有写dockerd在这个目录。根据搜索到的解决方法，执行

master@qiu-k8s-m:~$ sudo wget -qO- https://get.docker.com/ | sh
# Executing docker install script, commit: 4f282167c425347a931ccfd95cc91fab041d414f
Warning: the "docker" command appears to already exist on this system.

If you already have Docker installed, this script can cause trouble, which is
why we're displaying this warning and provide the opportunity to cancel the
installation.

If you installed the current Docker package using this script and are using it
again to update Docker, you can safely ignore this message.

You may press Ctrl+C now to abort this script.
+ sleep 20
+ sudo -E sh -c apt-get update -qq >/dev/null
+ sudo -E sh -c DEBIAN_FRONTEND=noninteractive apt-get install -y -qq apt-transport-https ca-certificates curl >/dev/null
W: APT had planned for dpkg to do more than it reported back (0 vs 4).
   Affected packages: docker-ce:amd64
+ sudo -E sh -c mkdir -p /etc/apt/keyrings && chmod -R 0755 /etc/apt/keyrings
+ sudo -E sh -c curl -fsSL "https://download.docker.com/linux/ubuntu/gpg" | gpg --dearmor --yes -o /etc/apt/keyrings/docker.gpg
gpg: WARNING: unsafe ownership on homedir '/home/master/.gnupg'
+ sudo -E sh -c chmod a+r /etc/apt/keyrings/docker.gpg
+ sudo -E sh -c echo "deb [arch=amd64 signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu bionic stable" > /etc/apt/sources.list.d/docker.list
+ sudo -E sh -c apt-get update -qq >/dev/null
+ sudo -E sh -c DEBIAN_FRONTEND=noninteractive apt-get install -y -qq --no-install-recommends docker-ce docker-ce-cli containerd.io docker-compose-plugin docker-scan-plugin >/dev/null
+ version_gte 20.10
+ [ -z  ]
+ return 0
+ sudo -E sh -c DEBIAN_FRONTEND=noninteractive apt-get install -y -qq docker-ce-rootless-extras >/dev/null
+ sudo -E sh -c docker version
Client: Docker Engine - Community
 Version:           20.10.18
 API version:       1.41
 Go version:        go1.18.6
 Git commit:        b40c2f6
 Built:             Thu Sep  8 23:11:34 2022
 OS/Arch:           linux/amd64
 Context:           default
 Experimental:      true

Server: Docker Engine - Community
 Engine:
  Version:          20.10.18
  API version:      1.41 (minimum version 1.12)
  Go version:       go1.18.6
  Git commit:       e42327a
  Built:            Thu Sep  8 23:09:28 2022
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          1.6.8
  GitCommit:        9cd3357b7fd7218e4aec3eae239db1f68a5a6ec6
 runc:
  Version:          1.1.4
  GitCommit:        v1.1.4-0-g5fd4c4d
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

================================================================================

To run Docker as a non-privileged user, consider setting up the
Docker daemon in rootless mode for your user:

    dockerd-rootless-setuptool.sh install

Visit https://docs.docker.com/go/rootless/ to learn about rootless mode.


To run the Docker daemon as a fully privileged service, but granting non-root
users access, refer to https://docs.docker.com/go/daemon-access/

WARNING: Access to the remote API on a privileged Docker daemon is equivalent
         to root access on the host. Refer to the 'Docker daemon attack surface'
         documentation for details: https://docs.docker.com/go/attack-surface/

================================================================================

再次键入docker ps则能正常显示。

那么键入docker-compose up，拉取镜像。正常的话可以看到flask的应用跑起来。

...
web_1    |  * Serving Flask app 'app.py'
web_1    |  * Debug mode: off
web_1    | WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.
web_1    |  * Running on all addresses (0.0.0.0)
web_1    |  * Running on http://127.0.0.1:5000
web_1    |  * Running on http://172.18.0.2:5000
...