diff --git a/Dockerfile b/Dockerfile
index d288f0d..cbe13cf 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -2,17 +2,22 @@
  
 RUN apt-get update && apt-get install -y wget git curl
 RUN apt-get update && apt-get install -y --no-install-recommends openjdk-7-jdk
-RUN apt-get update && apt-get install -y maven ant
-RUN wget -q -O - http://pkg.jenkins-ci.org/debian/jenkins-ci.org.key | sudo apt-key add -
-RUN echo deb http://pkg.jenkins-ci.org/debian binary/ >> /etc/apt/sources.list
+RUN apt-get update && apt-get install -y maven ant ruby rbenv make
+RUN echo "1.554.3" > .lts-version-number
+RUN wget -q -O - http://pkg.jenkins-ci.org/debian-stable/jenkins-ci.org.key | sudo apt-key add -
+RUN echo deb http://pkg.jenkins-ci.org/debian-stable binary/ >> /etc/apt/sources.list
 RUN apt-get update && apt-get install -y jenkins
 RUN mkdir -p /var/jenkins_home && chown -R jenkins /var/jenkins_home
 ADD init.groovy /tmp/WEB-INF/init.groovy
 RUN apt-get install -y zip && cd /tmp && zip -g /usr/share/jenkins/jenkins.war WEB-INF/init.groovy
 USER jenkins
 
-# VOLUME /var/jenkins_home
+# VOLUME /var/jenkins_home - bind this in via -v if you want to make this persistent.
 ENV JENKINS_HOME /var/jenkins_home
-EXPOSE 8080
-EXPOSE 50000
+
+# for main web interface:
+EXPOSE 8080 
+
+# will be used by attached slave agents:
+EXPOSE 50000 
 CMD ["/usr/bin/java",  "-jar",  "/usr/share/jenkins/jenkins.war"]
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