Unable to run Tomcat 7 as service inside container on CoreOS

Question

I am trying to setup tomcat 7 on Digital Ocean CoreOS machine but facing some problem, not sure how to solve them. I am following below tutorial provided by the Digital Ocean to setup Apache.

https://www.digitalocean.com/community/tutorials/how-to-create-and-run-a-service-on-a-coreos-cluster

I created docker container and run it using following command.

docker run -i -t ubuntu:14.04 /bin/bash

I was successfully able to install tomcat 7 by using below commands. (I followed this tutorial to setup tomcat 7 within the docker container: https://www.digitalocean.com/community/tutorials/how-to-install-apache-tomcat-7-on-ubuntu-14-04-via-apt-get)

sudo apt-get update 
sudo apt-get install tomcat7

Then I can created service unit file named as tomcat@.service

[Unit] 
Description=Tomcat 7 web server service 
After=etcd.service After=docker.service     
Requires=tomcat-discovery@%i.service

[Service] 
TimeoutStartSec=0 KillMode=none 
EnvironmentFile=/etc/environment 
ExecStartPre=-/usr/bin/docker kill tomcat%i 
ExecStartPre=-/usr/bin/docker rm tomcat%i 
ExecStartPre=/usr/bin/docker pull attacomsian/tomcat 
ExecStart=/usr/bin/docker run –name tomcat%i -p ${COREOS_PUBLIC_IPV4}:%i:8080 attacomsian/tomcat `service tomcat7 start` -D FOREGROUND 
ExecStop=/usr/bin/docker stop tomcat%i

[X-Fleet]
X-Conflicts=tomcat@*.service

Then I created tomcat-discovery@.service to register service states with Etcd as below

[Unit] 
Description=Announce Tomcat@%i service 
BindsTo=tomcat@%i.service

[Service] 
EnvironmentFile=/etc/environment
ExecStart=/bin/sh -c “while true; do etcdctl set /announce/services/tomcat%i ${COREOS_PUBLIC_IPV4}:%i –ttl 60; sleep 45; done” 
ExecStop=/usr/bin/etcdctl rm /announce/services/tomcat%i

[X-Fleet]
X-ConditionMachineOf=tomcat@%i.service

I submitted and loaded files to Fleet as below

fleetctl submit tomcat@.service tomcat-discovery@.service

fleetctl load tomcat@8080.service

fleetctl load tomcat-discovery@8080.service

Everything worked fine so far. I did not see any error. But when I tried to run the service as below

fleetctl start tomcat@8080.service

But it did not started. I can see it is appearing as dead.

I am new to CoreOS and still learning. I am managing servers at Digital Ocean and I quite about it quite well. I googled about this issue but did not found any help. I personally think following line is actually causing the trouble.

ExecStart=/usr/bin/docker run –name tomcat%i -p ${COREOS_PUBLIC_IPV4}:%i:8080 attacomsian/tomcat `service tomcat7 start` -D FOREGROUND

I would really appreciate any kind help to get this up.

Many Thanks

Attacomsian

Answer 1

I was going so suggest you take a look at what others have done and then discovered you have posted a similar question on the Docker Hub registry.

Did you take a look at the Docker file used by the tutum/tomcat image?

• https://github.com/tutumcloud/tutum-docker-tomcat/blob/master/7.0/Dockerfile
• https://github.com/tutumcloud/tutum-docker-tomcat/blob/master/7.0/run.sh

It runs a script called "run.sh" that runs tomcat in the foreground.

The thing that is tricky to understand is that Docker is not a virtual machine and therefore does not have any services running. You must run the docker processes explicitly or setup a process manager like runit or supervisord.

Hope this helps.