You can find here the slides and the sample code of my talk "Es muss nicht gleich Docker sein - IT Automation, die zu einem passt" that I presented on "JUG Münster" in Münster at 21st November 2018.

The code samples are tested with Ansible 2.4.0.0, Serverspec 2.40.0, Docker 17.06.2-ce and Docker Compose 1.16.1

I prepare some Vagrantfiles for the setup of the test infrastructure if necessary. The only prerequires are that you have to install VirtualBox and Vagrant on your machine. It is tested with Vagrant 2.0.0 . Then follow these steps:

1. Open a CLI and go to the location of the file Vagrantfile.
2. Call vagrant up. Vagrant will download the necessary image for VirtualBox. That will take some times.
3. Then copy your public key for the authentication that is needed for a SSH login. The password for the user vagrant is vagrant.

ssh-copy-id -i ~/.ssh/id_rsa [email protected]

Hint: Public and private keys can be generated with the following command: ssh-keygen

There exists three playbooks for setting up a database, installing Apache Tomcat and deploying WAR file on an installed Apache Tomcat

1. Go to the folder plain-ansible.
2. Start a virtual machine with vagrant up.
3. Call ansible-playbook -i inventories/test -u vagrant setup-db.yml for setting up the database.
4. Call ansible-playbook -i inventories/test -u vagrant setup-app.yml for installing Apache Tomcat.
5. Call ansible-playbook -i inventories/test -u vagrant deploy-demo.yml for deploying demo wep app on an installed Apache Tomcat.
6. Now the demo web application is available on http://192.168.33.10:8080/demo

The Serverspec tests are stored in the folder plain-ansible/spec/ansible_demo. To run the test, execute following steps, only prerequirement is that the virtualbox is provisioned wit h above Ansible playbooks:

1. Go to folder plain-ansible
2. Call rake spec

These examples shows how Ansible playbooks can reuse for Docker image builds.

1. Go to the folder docker-image-ansible.
2. Run shell script buildAll.sh for building Docker images based on Dockerfiles (tomcat.df and mysql.df) that include Ansible commands in RUN.
3. Run shell script buildDockerConnection.sh for building Docker images based on Docker file python-plain.df and Ansible Connection type docker .
4. Run shell script runAll.sh for running Docker container based on images from Docker files tomcat.df and mysql.df.
5. Run shell script stop.sh for stopping the container.
6. Call docker-compose -f docker-compose-ansible.yml up for running the Docker container based on Docker images built with using Ansible during the image build (see docker-compose-ansible.yml).
7. Call docker-compose -f docker-compose-ansibledocker.yml up for running the Docker container based on Docker images built with Ansible over connection type docker (see docker-compose-ansibledocker.yml).
8. Call docker-compose -f docker-compose-build.yml up for running the Docker container based on Dockerfiles with Ansible playbooks (see docker-compose-build.yml)

After starting the containers, the demo webapplication is available on http://localhost:8080/demo.

Precondition:

1. Create or modify /etc/docker/daemon.json with { "insecure-registries":["localhost:5000"] }
2. Restart docker daemon sudo service docker restart
3. Install Python docker package apt-get install python-docker.

These examples shows how to manage the Docker image lifecycle with Ansible playbook.

1. Go to folder docker-image-lifecycle.
2. Run shell script start-docker-registry.sh for starting docker registry.
3. Run shell script pushImages.sh for pushing images to docker registry with plain docker commands.
4. Call ansible-playbook build-and-push-images.yml --extra-vars "registry_hostname=localhost" for building the images of the last example and pushing these images to docker registry.
5. You can test if the images are in the registry with docker pull localhost:5000/sparsick/tomcat:plain or curl -s http://localhost:5000/v2/sparsick/tomcat/tags/list
6. Run shell script stop-docker-registry.sh for stopping docker registry.

This example bases on this blog post. The multi-module Maven project produces a small Java application that consumes memory and two Docker images with this application.

One Docker image bases Java 8 and the other bases on Java 10.

Following commands demonstrate Java's memory behaviour:

# Jar Running Outside Docker

$> java -jar memory-consumer-1.0-SNAPSHOT.jar
Initial free memory: 4332MB
Max memory: 4336MB
Reserve: 2047MB
Free memory: 2288MB

#Jar Running inside Docker
#Note: cgroup capabilties must be enabled

$> docker run sparsick/docker-java8-demo
Initial free memory: 4334MB
Max memory: 4336MB
Reserve: 2047MB
Free memory: 2287MB


$> docker run -m256M sparsick/docker-java8-demo
Initial free memory: 4334MB
Max memory: 4336MB
Reserve: 2047MB
Killed


$> docker run -m256M -e JAVA_OPT='-Xms64M -Xmx256M' sparsick/docker-java8-demo
Initial free memory: 227MB
Max memory: 228MB
Reserve: 181MB
Free memory: 48MB

#For JDK 8u131+ and JDK 9
$> docker run -m256M -e JAVA_OPT='-XX:+UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeap -XX:MaxRAMFraction=1' sparsick/docker-java8-demo
Initial free memory: 227MB
Max memory: 228MB
Reserve: 182MB
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
        at MemoryConsumer.main(MemoryConsumer.java:27)


$> docker run -m256M -e JAVA_OPT='-XX:+UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeap -XX:MaxRAMFraction=1 -Xms64M' sparsick/docker-java8-demo
Initial free memory: 227MB
Max memory: 228MB
Reserve: 181MB
Free memory: 50MB

# Java 10
$> docker run -m256M -e sparsick/docker-java10-demo
Initial free memory: 120MB
Max memory: 121MB
Reserve: 96MB
Free memory: 24MB

Here is the source code of the sample web application. It's the application for the deployment samples and it demonstrates how we can use Docker container in our integration tests integrated in the build. For this Testcontainers is used. Ensure that a Docker Daemon (dockerd) runs your machine.

Test classes DbMigrationITest and PersonRepositoryITest demonstate the integration of a Docker container in our test.