create docker image for testing of sonar plugin

[romani]

We need to combine:
https://hub.docker.com/_/sonarqube/
ubuntu+maven+jdk8+git
to create new public image for hub.docker.com owned by checkstyle organization.

to adjust wercker CI to use it as base system.
In that system we need to:

1. clone sonar-checkstyle sources
2. package all
3. install in sonar
4. restart sonar
5. make sure sonar is starting
6. do test launch of "mvn sonar:sonar" against sonar-checkstyle sources. No errors are expected.

[romani]

Git in docker - https://github.com/kr1sp1n/docker-git/blob/master/Dockerfile

Sonar docker https://github.com/SonarSource/docker-sonarqube/blob/f63921d773162fde17179f9cc5e78640c88b2ae6/6.2/Dockerfile is based on jdk8 https://github.com/docker-library/openjdk/blob/e6e9cf8b21516ba764189916d35be57486203c95/8-jdk/Dockerfile .

Maven could be intalled as shown here https://github.com/carlossg/docker-maven/blob/33eeccbb0ce15440f5ccebcd87040c6be2bf9e91/jdk-8/Dockerfile

[romani]

git clone https://github.com/checkstyle/sonar-checkstyle.git
cd sonar-checkstyle
mvn package
cp checkstyle-sonar-plugin/target/checkstyle-sonar-plugin-3.6-SNAPSHOT.jar ../extensions/plugins/
curl -X POST http://localhost:9000/api/system/restart -u admin:admin
#wait for restart
sleep 20
# just force sonarqube to do smth base on his defaults
mvn sonar:sonar

[MEZk]

@romani
Might be useful
https://github.com/spotify/docker-maven-plugin

[romani]

pushing to docker hub - https://docs.docker.com/docker-hub/repos/

So we need to create user "checkstyle" , name of docker images will be
https://hub.docker.com/r/checkstyle/sonarqube-maven-git/ ( I did this base on assumption - https://hub.docker.com/r/jboesl/mssql-server-linux/ )

organization can not be created as it is require billing information, so we should stay with user.

[romani]

done , example of failure - https://app.wercker.com/checkstyle/sonar-checkstyle/runs/build/58abc664e560360100d6bc74?step=58abc66ad2fd510001653fcb

for now docker image will be hosted in my private user, as it become stable I will move it to "checkstyle" user.

[romani]

image - https://hub.docker.com/r/romani/sonarqube-maven-git/

[romani]

side note:
I failed to install "less" tool to docker. Package is easy to install, package "less", but during to launch it is failing with "WARNING: terminal is not fully functional".