After testing Docker on a couple of configurations (laptop/server/Raspberry Pi) on earth it was time to go in the air and use the cloud. As Docker runs on a number of Unix distributions it should be easy to use Docker in the cloud as a lot of cloud vendors offer compatible distributions. Some of the vendors that are able to run Docker in the cloud are DigitalOcean, Rackspace and Amazon EC2. As I’m a Dutch guy I wanted the cheapest option and luckily Amazon offers a free option.

Setup

Register for Amazon AWS and create an instance following the instructions on the Docker site. For this test I used an ‘Ubuntu Server 13.10 (PV)’. This is the same Ubuntu version as I used for previous blogs and it’s one of the free instances.

Security groups

Configure the correct security groups in Amazon EC2. Configure SSH to connect to the instance and HTTP to connect to Tomcat.

Connecting with SSH

Download the pem file and use it to connect to your instance. The command should be like this:

ssh -i <filename>.pem ubuntu@ec2-XXXXXXXX.us-west-2.compute.amazonaws.com

Be careful, the username is ‘ubuntu‘ and not the ‘ec2-user‘ which was mentioned in the documentation.

Install Docker

Simply use the same commands as mentioned in the previous blog.

sudo apt-get update
sudo apt-get install linux-image-extra-`uname -r`
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 36A1D7869245C8950F966E92D8576A8BA88D21E9
sudo sh -c "echo deb http://get.docker.io/ubuntu docker main > /etc/apt/sources.list.d/docker.list"
sudo apt-get update
sudo apt-get install lxc-docker
sudo docker run -i -t ubuntu /bin/bash

Creating a Docker container

Create a ‘Dockerfile’ for instance with ‘nano’ with the following content:

FROM ubuntu:saucy
# Update Ubuntu
RUN apt-get update && apt-get -y upgrade
# Add oracle java 7 repository
RUN apt-get -y install software-properties-common
RUN add-apt-repository ppa:webupd8team/java
RUN apt-get -y update
# Accept the Oracle Java license
RUN echo "oracle-java7-installer shared/accepted-oracle-license-v1-1 boolean true" | debconf-set-selections
# Install Oracle Java
RUN apt-get -y install oracle-java7-installer
# Install tomcat
RUN apt-get -y install tomcat7
RUN echo "JAVA_HOME=/usr/lib/jvm/java-7-oracle" >> /etc/default/tomcat7
EXPOSE 8080
# Download Slashdot homepage
RUN mkdir /var/lib/tomcat7/webapps/slashdot
RUN wget http://www.slashdot.org -P /var/lib/tomcat7/webapps/Slashdot
RUN wget http://tomcat.apache.org/tomcat-7.0-doc/appdev/sample/sample.war -P /var/lib/tomcat7/webapps
# Start Tomcat, after starting Tomcat the container will stop. So use a 'trick' to keep it running.
CMD service tomcat7 start && tail -f /var/lib/tomcat7/logs/catalina.out

Build the container using the following command:

sudo docker build -t tomcat7 .

Start the Docker container

Start the container using the following command:

sudo docker run -p 80:8080 -d tomcat7

Test the Docker container

Try the following URL’s in your browser:

• http://<AMAZON-INSTANCE-PUBLIC-IP>/Slashdot/
• http://<AMAZON-INSTANCE-PUBLIC-IP>/sample/

Conclusion

Docker is working perfectly in the cloud. This blog and my previous blogs show that Docker can run on various configurations. Not only on standard laptops or servers, but also on ARM (Raspberry Pi) and in the cloud. Using Docker containers to run your applications gives companies a lot of flexibility. It is possible to quickly deploy the applications on another platform. Moving applications across platforms enables companies to use resources more effectively and even gives them the possibility to run the applications on the ‘cheapest platform of the day’.

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