Problem Statement
Explain Jenkins backup and disaster recovery strategies. What should be backed up, how often, and how to restore?
Explanation
Critical data to backup includes JENKINS_HOME directory containing jobs (jobs/ directory with job configurations), builds (builds/ directory with build history and artifacts, though often excluded due to size), plugins (plugins/ directory), system configuration (config.xml, credentials.xml, secrets/), user content (userContent/), and workspace (workspace/ rarely backed up as it's recreatable). Essential are job configurations, credentials, and system configuration; build history and artifacts are optional (can be large).
Backup strategies: full backup copies entire JENKINS_HOME periodically (weekly), incremental backup copies only changes since last backup (daily), configuration-only backup excludes builds and workspaces (small, frequent). Use thinBackup plugin for automated scheduled backups with retention policies, or Jenkins Backup Plugin, or filesystem-level backups (LVM snapshots, AWS EBS snapshots). Store backups offsite (S3, Azure Blob, separate datacenter) for disaster recovery.
Configuration as Code approach: use Jenkins Configuration as Code (JCasC) plugin storing configuration as YAML in version control, Job DSL Plugin or Pipeline for job definitions as code, Credentials stored in external secret management. This enables treating Jenkins as cattle not pets, recreating from code rather than restoring from backup. Combine with backup strategy for defense in depth.
Backup schedule and retention: configuration backups daily with 30-day retention, full backups weekly with 4-week retention, monthly backups kept for 12 months. Automate with cron or Jenkins job. Test backups regularly (monthly) by restoring to test environment verifying configuration and jobs work correctly. Untested backups are useless.
What to exclude from backups: workspace directories (recreatable from SCM), fingerprints (not critical), large build artifacts (store in artifact repository instead), old build history (implement retention policy). This reduces backup size and time significantly.
Disaster recovery procedures: install Jenkins on new server matching version of backed-up instance, stop Jenkins service, restore JENKINS_HOME from backup overwriting new installation, install required plugins (from backed-up plugins list or JCasC), start Jenkins service, verify jobs run correctly, reconfigure agents (agents will reconnect), update DNS or load balancer to point to new instance. Document step-by-step DR procedures with screenshots.
High Availability options: Jenkins HA with active-passive setup sharing JENKINS_HOME on network storage, or CloudBees Jenkins Enterprise with HA features. Shared filesystem (NFS, EFS) enables fast failover. Test failover procedures regularly. For critical installations, implement HA rather than relying solely on backups.
Backup automation example:
```groovy
pipeline {
agent any
triggers { cron('H 2 * * *') } // Daily at ~2 AM
stages {
stage('Backup') {
steps {
sh '''
tar -czf jenkins-backup-$(date +%Y%m%d).tar.gz \
--exclude='workspace/*' \
--exclude='builds/*/archive' \
$JENKINS_HOME
'''
sh 'aws s3 cp jenkins-backup-*.tar.gz s3://backups/jenkins/'
sh 'find . -name "jenkins-backup-*.tar.gz" -mtime +30 -delete'
}
}
}
}
```
Understanding backup and DR strategies ensures business continuity and quick recovery from failures, critical for organizations relying on Jenkins for software delivery.