Install Jenkins CI & Configure Open-JDK 8 on Debian-based System

install-jenkins.sh

#!/bin/bash

echo "==================================================================="
echo
echo "Installs Jenkins & Open-JDK 8"
echo "You may be prompted for root credentials to complete the install."
echo
echo "==================================================================="

set -o nounset                    # unset variables are errors

SCRIPTVERSION="2019.01.29"
SCRIPTNAME="install-jenkins.sh"
SCRIPTFULLNAME="$0"
PORT='8080'
HEAPSIZE='512'

echoerror() { printf "\033[1;31m * ERROR\033[0m: %s\\n" "$@" 1>&2; }

usage() {
  cat << EOT
    Usage :  ${SCRIPTNAME} [options] 

    Options:
      -h  Display this message
      -v  Display script version
      -p  Http port number desired for the Jenkins instance.  Default is 8080.
      -s  Heap size desired for Jenkins to avoid performance issues with builds. Default is 512 MB.
EOT
}   # ----------  end of function usage  ----------

while getopts ':hvp:s:' opt
do
  case "${opt}" in

    h )  usage; exit 0                                ;;
    v )  echo "$0 -- Version $SCRIPTVERSION"; exit 0  ;;    
    p )  PORT=$OPTARG                                 ;;
    s )  HEAPSIZE=$OPTARG                             ;;

    \?)  echo
          echoerror "Option does not exist : $OPTARG"
          usage
          exit 1
        ;;

  esac    # --- end of case ---
done
shift $((OPTIND-1))

if [ -f /etc/default/jenkins ]; then
  echo "Jenkins is already installed on $HOSTNAME."
else  
  echo "************************ JENKINS INSTALL **************************"
  echo "Installing Jenkins."
  echo "You may be prompted for root credentials to complete the install."
  echo "******************************************************************" 
  
  #Install Jenkins & compliant Java 8 dependency
  wget -qO- https://pkg.jenkins.io/debian/jenkins.io.key | sudo bash -c "apt-key add"  
  sudo bash -c "echo 'deb http://pkg.jenkins.io/debian-stable binary/' >> /etc/apt/sources.list.d/jenkins.list"
  
  sudo bash -c "apt update && apt upgrade -y" 
  sudo bash -c "apt install openjdk-8-jdk jenkins -y"  
  
  #Set JAVA_HOME to openJDK-8
  sudo bash -c "update-alternatives --set java /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java"
  sudo bash -c "echo 'JAVA_HOME=\"/usr/lib/jvm/java-8-openjdk-amd64/jre\"' >> /etc/environment"
  source /etc/environment
  
  #Set port value in Jenkins configuration if an alternate port was passed to the script
  if [ "$PORT" != "8080" ]; then
    sudo bash -c "sed -i -e 's/HTTP_PORT=8080/HTTP_PORT=$PORT/g' /etc/default/jenkins" 
  fi    
  
  #Set maximum heap size for Jenkins
  sudo bash -c "sed -i -e 's/#JAVA_ARGS=\"-Xmx256m\"/JAVA_ARGS=\"-Xmx$HEAPSIZEm\"/g' /etc/default/jenkins"
   
  sudo bash -c "ufw allow $PORT && ufw enable"  
  sudo bash -c "systemctl enable jenkins.service && service jenkins restart"
  
  INITPASSWD=$( sudo bash -c "cat /var/lib/jenkins/secrets/initialAdminPassword" )
  
  echo "$SCRIPTFULLNAME ($SCRIPTVERSION) complete."
  echo "Browse http://$HOSTNAME:$PORT to unlock Jenkins with this password:"
  echo $INITPASSWD  
fi