Why docker container exits immediately

Question

I run a container in the background using

 docker run -d --name hadoop h_Service 

it exits quickly. But if I run in the foreground, it works fine. I checked logs using

docker logs hadoop 

there was no error. Any ideas?

DOCKERFILE

 FROM java_ubuntu_new  RUN wget http://archive.cloudera.com/cdh4/one-click-install/precise/amd64/cdh4-repository_1.0_all.deb  RUN dpkg -i cdh4-repository_1.0_all.deb  RUN curl -s http://archive.cloudera.com/cdh4/ubuntu/precise/amd64/cdh/archive.key | apt-key add -  RUN  apt-get update  RUN apt-get install -y hadoop-0.20-conf-pseudo  RUN dpkg -L hadoop-0.20-conf-pseudo  USER hdfs  RUN hdfs namenode -format  USER root  RUN apt-get install -y sudo  ADD . /usr/local/  RUN chmod 777 /usr/local/start-all.sh  CMD ["/usr/local/start-all.sh"] 

start-all.sh

 #!/usr/bin/env bash  /etc/init.d/hadoop-hdfs-namenode start  /etc/init.d/hadoop-hdfs-datanode start  /etc/init.d/hadoop-hdfs-secondarynamenode start  /etc/init.d/hadoop-0.20-mapreduce-tasktracker start  sudo -u hdfs hadoop fs -chmod 777 /  /etc/init.d/hadoop-0.20-mapreduce-jobtracker start  /bin/bash 

Answer 1

This did the trick for me:

docker run -dit ubuntu 

After it, I checked for the processes running using:

docker ps -a 

For attaching again the container

docker attach CONTAINER_NAME 

TIP: For exiting without stopping the container type: ^P^Q

Answer 2

A docker container exits when its main process finishes.

In this case it will exit when your start-all.sh script ends. I don't know enough about hadoop to tell you how to do it in this case, but you need to either leave something running in the foreground or use a process manager such as runit or supervisord to run the processes.

I think you must be mistaken about it working if you don't specify -d; it should have exactly the same effect. I suspect you launched it with a slightly different command or using -it which will change things.

A simple solution may be to add something like:

while true; do sleep 1000; done

to the end of the script. I don't like this however, as the script should really be monitoring the processes it kicked off.

(I should say I stole that code from https://github.com/sequenceiq/hadoop-docker/blob/master/bootstrap.sh)