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Server Migration Guide

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David Bau edited this page Dec 29, 2025 · 1 revision

Server Migration Guide

This page documents the process for migrating infrastructure servers to new hardware or Ubuntu versions.

Overview

The baulab.us cluster runs on Ubuntu LTS releases. Migration is needed when:

  • Hardware reaches end-of-life
  • Ubuntu version goes out of support (20.04 → 24.04)
  • Expanding capacity

Current Infrastructure

Server Ubuntu Role Migration Status
baunames 20.04 LDAP, Ansible → baunames24
bauserver 20.04 Web server → bauserver24
baushare Synology DSM NAS No migration needed
baunas24 Synology DSM NAS No migration needed

Migration Scripts

Migration scripts are located in /home/localdavidbau/admin/lab/scripts/:

Script Purpose
backup_ldap_full.sh Complete LDAP backup
gather_system_info.sh Collect system info for planning
restore_ldap_server.sh Restore LDAP to new server

LDAP Server Migration

Step 1: Backup Current Server

On baunames (old server):

cd /home/localdavidbau/admin/lab/scripts
sudo ./backup_ldap_full.sh

# Backup is saved to /share/backup/ldap-full-YYYYMMDD-HHMMSS/

This backs up:

  • LDAP configuration (slapcat -n 0)
  • LDAP data (slapcat -n 1)
  • TLS certificates
  • phpLDAPadmin config

Step 2: Prepare New Server

On baunames24 (new server):

# Install base packages
sudo apt update
sudo apt install -y slapd ldap-utils

# Stop slapd for restoration
sudo systemctl stop slapd

Step 3: Restore Data

# Copy backup to new server
scp -r /share/backup/ldap-full-LATEST localdavidbau@baunames24:/tmp/

# On new server, run restore script
ssh baunames24
cd /tmp/ldap-full-LATEST
sudo ./restore_ldap_server.sh

Step 4: Update TLS Certificates

Generate new certificates for the new hostname:

# On new server
sudo openssl req -x509 -nodes -days 3650 \
  -newkey rsa:2048 \
  -keyout /etc/ldap/baunames24_slapd_key.pem \
  -out /etc/ldap/baunames24_slapd_cert.pem \
  -subj "/CN=baunames24.khoury.northeastern.edu"

sudo chown openldap:openldap /etc/ldap/baunames24_slapd_*.pem
sudo chmod 640 /etc/ldap/baunames24_slapd_key.pem

Update LDAP TLS config:

cat > /tmp/tls.ldif << EOF
dn: cn=config
changetype: modify
replace: olcTLSCertificateFile
olcTLSCertificateFile: /etc/ldap/baunames24_slapd_cert.pem
-
replace: olcTLSCertificateKeyFile
olcTLSCertificateKeyFile: /etc/ldap/baunames24_slapd_key.pem
EOF

sudo ldapmodify -Y EXTERNAL -H ldapi:/// -f /tmp/tls.ldif

Step 5: Update Clients

Update all client machines to point to new LDAP server:

# On baunames (ansible controller)
cd /srv/ansible24

# Edit ldap-client/sssd.conf to update ldap_uri
# ldap_uri = ldaps://baunames24.khoury.northeastern.edu

# Deploy to all clients
ansible-playbook ldapclient.yml

Step 6: Verify

# Test LDAP connectivity from a client
ldapsearch -x -H ldap://baunames24 -b "dc=baulab,dc=us" "(uid=davidbau)"

# Test login
ssh testuser@someclient

Web Server Migration

Step 1: Backup

# On bauserver
sudo tar -czf /share/backup/bauserver-$(date +%Y%m%d).tar.gz \
  /etc/apache2 \
  /etc/letsencrypt \
  /var/www

Step 2: Install on New Server

# On bauserver24
sudo apt install -y apache2 libapache2-mod-wsgi-py3

# Enable modules
sudo a2enmod ssl rewrite proxy proxy_http wsgi

Step 3: Restore Configuration

# Copy sites-available configs
sudo cp /share/backup/bauserver-*/etc/apache2/sites-available/* /etc/apache2/sites-available/

# Copy SSL certificates
sudo cp -r /share/backup/bauserver-*/etc/letsencrypt /etc/

# Enable sites
sudo a2ensite baulab-ssl
sudo systemctl reload apache2

Step 4: Update DNS

Contact Khoury IT to update DNS records:

  • baulab.us → new bauserver24 IP
  • shell.baulab.us → new IP

Ansible Migration

The /srv/ansible24/ directory contains playbooks updated for Ubuntu 24.04.

Key Differences (20.04 → 24.04)

Component 20.04 24.04
Python 3.8 3.12
SSSD config Minor changes Updated options
systemd Same Same

Updating Playbooks

  1. Test on single machine first:

    ansible-playbook main.yml -l testhost --check

  2. Apply to one machine:

    ansible-playbook main.yml -l testhost

  3. Roll out to all:

    ansible-playbook main.yml

Pre-Migration Checklist

  • Document current IP addresses and DNS entries
  • Backup all configuration files
  • Test backups can be restored (on test VM)
  • Schedule maintenance window
  • Notify users of downtime
  • Verify new hardware is on network
  • Update inventory in /etc/ansible/hosts

Post-Migration Checklist

  • All users can log in
  • NFS mounts work
  • Web services accessible
  • SSL certificates valid
  • Monitoring configured
  • Old server decommissioned (but kept as backup)

Rollback Plan

If migration fails:

  1. Stop services on new server
  2. Update DNS/client configs back to old server
  3. Restart services on old server
  4. Investigate and retry migration

Keep old server running (powered off or isolated) for at least 30 days after successful migration.

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