Automated Jenkins Upgrade Script

jenkins-upgrade-script.sh

#!/bin/bash
# This script will auto upgrade jenkins to latest stable version if found.

export EPOCH_DATE="$(date +%s)"
export JENKINS_UPGRADE_URL="http://mirrors.jenkins-ci.org/war-stable/latest/jenkins.war"
export JENKINS_DIR="/usr/share/java"
export TEMP_DIR="/tmp/jenkins-upgrade-"$EPOCH_DATE"/"
export WEBHOOK="https://hooks.slack.com/services/XXXX/YYYY/ZZZZZ"

# Create temp directory
mkdir "$TEMP_DIR"

# download latest stable war file to temp directory
wget "$JENKINS_UPGRADE_URL" -P "$TEMP_DIR"/ || exit 1

# Check MD5 of new and old jenkins
export NEW_JENKINS_MD5="$(md5sum /tmp/jenkins-upgrade-"$EPOCH_DATE"/jenkins.war | awk '{print $1}')"
export OLD_JENKINS_MD5="$(md5sum "$JENKINS_DIR/jenkins.war" | awk '{print $1}')"
if [ "$NEW_JENKINS_MD5" != "$OLD_JENKINS_MD5" ]; then
  echo "Jenkins Upgrade Available. Upgrading..."
  curl -X POST -H 'Content-type: application/json' --data '{"text":"Jenkins Upgrade Available. Upgrading..."}' "$WEBHOOK"
  while true; do
    # stop the jenkins service
    if systemctl stop jenkins.service 2> /dev/null; then
      # move the current war file to backup
      cp "$JENKINS_DIR"/jenkins.war "$JENKINS_DIR"/jenkins.war-"$EPOCH_DATE"
      # move the latest war file to current
      cp "$TEMP_DIR"/jenkins.war "$JENKINS_DIR"/
      # start the jenkins service
      systemctl start jenkins.service
      sleep 5
      # check connectivity to check service is running properly, else revert to older version
      if echo -e '\x1dclose\x0d' | telnet localhost 8080 > /dev/null 2>&1; then
        echo "Jenkins Started Successfully"
        curl -X POST -H 'Content-type: application/json' --data '{"text":"Jenkins Started Successfully"}' "$WEBHOOK"
        break
      else
        echo "Jenkins Failed to start. Manual intervention required."
        curl -X POST -H 'Content-type: application/json' --data '{"text":"Jenkins Failed to start. Manual intervention required."}' "$WEBHOOK"
        break
      fi
    else
      echo "Unable to stop Jenkins for upgrade. Retrying in 5 mins"
      curl -X POST -H 'Content-type: application/json' --data '{"text":"Unable to stop Jenkins for upgrade. Retrying in 5 mins."}' "$WEBHOOK"
      sleep 5
    fi
  done
else
  echo "No Upgrade available."
fi

# Removing temporary stuff
rm -rf "$TEMP_DIR"