自訂 Docker image 範例

這個範例從CentOS 6 image上安裝sshd、supervisord、JDK 1.7、Tomcat 7、MySQL，並且預設啟動supervisord，再由supervisord自動帶起sshd、MySQL。

Dockerfile

FROM centos:centos6

MAINTAINER Linus Chien <linus_chien@mail.gss.com.tw>

RUN yum install -y openssh-server java-1.7.0-openjdk wget tar python-setuptools mysql-server

# setup root's password
RUN echo 'root:12345678' | chpasswd

# SSH login fix. Otherwise user is kicked off after login
RUN sed 's@session\s*required\s*pam_loginuid.so@session optional pam_loginuid.so@g' -i /etc/pam.d/sshd

# init SSH keys
RUN /sbin/service sshd start && /sbin/service sshd stop

# init MySQL database
RUN /sbin/service mysqld start && /sbin/service mysqld stop

ENV TOMCAT_SITE https://archive.apache.org/dist/tomcat
ENV TOMCAT_MAJOR_VERSION 7
ENV TOMCAT_MINOR_VERSION 7.0.57

RUN wget -q ${TOMCAT_SITE}/tomcat-${TOMCAT_MAJOR_VERSION}/v${TOMCAT_MINOR_VERSION}/bin/apache-tomcat-${TOMCAT_MINOR_VERSION}.tar.gz && \
    wget -qO- ${TOMCAT_SITE}/tomcat-${TOMCAT_MAJOR_VERSION}/v${TOMCAT_MINOR_VERSION}/bin/apache-tomcat-${TOMCAT_MINOR_VERSION}.tar.gz.md5 | md5sum -c - && \
    tar zxf apache-tomcat-*.tar.gz && \
    rm apache-tomcat-*.tar.gz && \
    mv apache-tomcat* /opt/

RUN easy_install supervisor

ADD supervisord.conf /etc/supervisord.conf

EXPOSE 22 3306 8080

CMD ["/usr/bin/supervisord", "-c", "/etc/supervisord.conf"]

supervisord.conf

[supervisord]
logfile=/tmp/supervisord.log ; (main log file;default $CWD/supervisord.log)
logfile_maxbytes=10MB        ; (max main logfile bytes b4 rotation;default 50MB)
logfile_backups=10           ; (num of main logfile rotation backups;default 10)
loglevel=info                ; (log level;default info; others: debug,warn,trace)
pidfile=/tmp/supervisord.pid ; (supervisord pidfile;default supervisord.pid)
nodaemon=true                ; (start in foreground if true;default false)
minfds=1024                  ; (min. avail startup file descriptors;default 1024)
minprocs=200                 ; (min. avail process descriptors;default 200)

;[program:apache2]
;command = /usr/sbin/httpd -D FOREGROUND
;priority = 30

;[program:tomcat7]
;command = /opt/apache-tomcat-7.0.57/bin/catalina.sh run
;priority = 20

[program:mysql5]
command = /usr/bin/pidproxy /var/run/mysqld/mysqld.pid /usr/bin/mysqld_safe
priority = 10

[program:sshd]
command = /usr/sbin/sshd -D
priority = 40

步驟：

1. 安裝docker，並啟動，細節請自行參閱官方文件。
2. 準備好上述兩個檔案：Dockerfile、supervisord.conf
3. 執行

• docker build -t cao:tomcat7 . # use your own tag name, don't miss the dot
• docker run -d --name="tomcat" cao:tomcat7 # assign a unique name to container for convenience
• docker inspect tomcat # you can find container's IP address
• ssh {IP} # default root's password setup in Dockerfile

Docker 常用指令

1. docker search {keyword} # 搜尋雲端images
2. docker pull {image} # 將雲端image拉回主機
3. docker build -t {tag} {path} # 使用Dockerfile建立image
4. docker run {options} {image} {command} # 從image執行指令(建立container)
5. docker run -i -t {image} /bin/bash # 進入container shell，(ctrl+p) + (ctrl+q)可丟背景離開shell
6. docker inspect --format='{{.NetworkSettings.IPAddress}}' {container} # 查看container IP
7. docker images # 查看local所有的images
8. docker ps -a # 查看container包含已結束的
9. docker rm {container} # 移除已結束的container
10. docker rm $(docker ps -a -q) # 移除所有container
11. docker rmi {image} # 移除image
12. docker commit {comtainer} {image} # 將container異動過的內容寫入image
13. docker start {container} # 重新啟動已結束的container
14. docker attach {container} # 重新接入正在執行container
15. docker save {image} > {tarball} # 備份image
16. docker load < {tarball} # 還原image