Docker container is exiting immediately

Question

using docker run -it -v /root/apache-cassandra-3.9:/root/apache-cassandra-3.9 --name=cassan_8 cassan_8 but exiting immediately, no errors in events. Image is created from dockerfile

[root@ip-10-0-1-186 ~]# cat Dockerfile FROM centos:6 RUN yum install -y httpd RUN yum install -y centos-release-scl RUN yum install -y python27 RUN yum install -y java-1.8.0-openjdk ADD apache-cassandra-3.9/bin/cassandra /usr/local/bin ADD cassandra.sh /usr/local RUN chmod 755 /usr/local/cassandra.sh EXPOSE 7000 7001 7199 9042 9160 WORKDIR /root/apache-cassandra-3.9/bin CMD ["/usr/local/cassandra.sh"]

[root@ip-10-0-1-186 ~]# cat cassandra.sh
#!/bin/sh
/root/apache-cassandra-3.9/bin/cassandra -R & >> naresh.txt

Answer 1

You're using cassandra as the entry point, but you're also sending it to the background:

/root/apache-cassandra-3.9/bin/cassandra -R & >> naresh.txt

Therefore, this line immediately returns. For Docker, as soon as the command has finished, the container has fulfilled its purpose, and therefore, the container is shut down.

Possible approaches to prevent this:

• keep cassandra in the foreground by omitting the & (assuming that cassandra keeps running in the foreground and doesn't fork)
• add another command at the end of your cassandra.sh that never returns (a good candidate is tail -f <some logfile> )
• wait for cassandra with waitpid

UPDATE

The advice regarding wait for cassandra is incomplete; a complete minimal solution would be:

/root/apache-cassandra-3.9/bin/cassandra -R & >> naresh.txt
childPID=$!
wait $childPID

(I stole this idea from the startup script used in the official Docker images for Oracle RDBMS )