Example of how to automatically start an application service in a Docker container

If you want the application service in the Docker container to start automatically when the container is started. You only need to write the service startup script in the Dockerfile, and then use the Dockerfile to reconstruct the image:

• Write an application service self-start script
• Writing a Dockerfile
• Reconstructing the image
• Open the container

Write a service self-start script (dockerd)
(Take Tomcat as an example)

#!/bin/bash
#
# 
#
# chkconfig: 345 98 30
# description: tomcat program.
# processname: tomcat
# Source function library.
. /etc/rc.d/init.d/functions
# Source networking configuration.
#. /etc/sysconfig/network


prog="tomcat"

checkprocess()
{
  chkret=`ps -ef |grep $prog |grep -v "grep" |wc -l`
    return $chkret
}

start()
{
    cd /usr/local/tomcat/bin/
   ./startup.sh
  echo "Service $prog started!"
}

#/usr/sbin/nscd &
/usr/sbin/sshd -D &
while [ true ]
do
        DNSIP=172.18.3.179
          ping=`ping -c 3 $DNSIP|awk 'NR==7 {print $4}'`
        if [[ $ping -eq "3" ]]
        then
            break
        fi
    sleep 3
done

while [ true ]
do
    checkprocess
     if [[ $chkret -eq "0" ]]
        then
              start
     #nscd -i hosts
        else 
          echo "Service $prog is running."

        fi
    sleep 60
done
exit 0

Writing a Dockerfile

FROM tomcat

MAINTAINER liu "[email protected]"

ADD dockerd /etc/rc.d/init.d/
RUN chmod 777 /etc/rc.d/init.d/dockerd

ENV JAVA_HOME /usr/local/jdk1.6.0_30
ENV PATH $JAVA_HOME/bin:$PATH
ENV CLASSPATH .:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar

CMD /etc/rc.d/init.d/dockerd

Among them, ADD adds the scripts in the same directory to the specified location of the image, and ENV sets the Java environment variable (very important, the self-starting script cannot be executed successfully without this sentence). There can only be one CMD command, which is used to execute commands when the container starts. It can also be a script.

Reconstructing the image
**pass
docker build -t new image name.
Successfully created a new image

Open the container

docker run -d -h="s" –name="s" new image name

Then, I found that tomcat was already started

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