Use Java 8 when installing Jenkins (#10)

* Create Jenkins home directory when creating user

Note: This change means that the Jenkins home directory will have a
mode of 0755 instead of 0777, as it was before.

* Use /bin/false for the Jenkins user's shell

* Move Java version to variable for apt installation

This change allows the user to specify a list of apt packages and a
specific Java version to use on the Jenkins master instance.

As of Jenkins 2.54, Java 8 is required. For more information, see:
https://jenkins.io/blog/2017/04/10/jenkins-has-upgraded-to-java-8/

Author: nre-ableton

README.md

@@ -96,6 +96,19 @@ jenkins_docker_container_name: jenkins
 jenkins_docker_expose_port: true
 ```
 
+Debian-Specific Role Variables
+------------------------------
+
+```yml
+# Packages which are to be installed on the jenkins instance
+jenkins_apt_packages:
+  - openjdk-8-jdk
+
+# Java version to use. Note that JDK 8 is required for Jenkins
+# 2.54 or greater.
+jenkins_java_version: "java-1.8.0-openjdk-amd64"
+```
+
 Example Playbook
 ----------------
 

tasks/apt/install.yml

@@ -1,5 +1,8 @@
 ---
 
+- name: Include Debian-specific variables
+  include_vars: "debian.yml"
+
 - name: Create Jenkins group
   group:
     name: "{{ jenkins_config_group }}"
@@ -9,16 +12,10 @@
   user:
     name: "{{ jenkins_config_owner }}"
     group: "{{ jenkins_config_group }}"
+    home: "{{ jenkins_home }}"
+    shell: "/bin/false"
     state: present
 
-- name: Ensure jenkins home dir is created
-  file:
-    path: "{{ jenkins_home }}"
-    mode: 0777
-    owner: "{{ jenkins_config_owner }}"
-    group: "{{ jenkins_config_group }}"
-    state: directory
-
 - name: Install apt PPA dependencies
   apt:
     name: python-software-properties
@@ -45,13 +42,12 @@
     group: root
     mode: 0644
 
-- name: Install OpenJDK 7
-  apt:
-    name: openjdk-7-jdk
-    update_cache: yes
+- name: Install apt packages
+  action: apt name={{ item }} state=present
+  with_items: "{{ jenkins_apt_packages }}"
 
-- name: Update java alternatives
-  shell: /usr/sbin/update-java-alternatives -s java-1.7.0-openjdk-amd64
+- name: Set default Java version
+  shell: /usr/sbin/update-java-alternatives -s "{{ jenkins_java_version }}"
   ignore_errors: yes
 
 - name: Add Jenkins key

vars/debian.yml

@@ -0,0 +1,6 @@
+---
+
+jenkins_apt_packages:
+  - openjdk-8-jdk
+
+jenkins_java_version: "java-1.8.0-openjdk-amd64"