--- title: "Replication and Failover of a Docker Environment: From Proxmox Container to Cloud — Paolo Ronco" language: "en" url: "https://paoloronco.it/en/writing/1377-2" --- [← writing](/en/writing) 15 July 2025 · 3 min read # Replication and Failover of a Docker Environment: From Proxmox Container to Cloud Managing a website on a local server (on-premises) offers many advantages in terms of control and customization, but it also brings an important risk: operational continuity. A home or office server cannot guarantee 100% uptime — just one blackout, a hardware issue, or, as in my case, being away during holidays, and the site could remain offline for hours or days. * * * Managing a website on a local server (on-premises) offers many advantages in terms of control and customization, but it also brings an important risk: operational continuity. A home or office server cannot guarantee 100% uptime — just one blackout, a hardware issue, or, as in my case, being away during holidays, and the site could remain offline for hours or days. For this reason, I decided to implement a **Replication + Cloud Failover** solution, which allows: - **Periodic Replication** of WordPress content and database from the local server to the cloud - **Automatic (or Semi-Automatic) Failover** in case the local server is offline - The ability to manage and update services remotely as well ## How Does My Solution Work? 1. **Local → Cloud Replication** - Every night, backup scripts for web servers and WordPress database are executed - Files are transferred via `scp` to the cloud server with SSH key authentication 2. **Cloud Restore** - In the morning, cronjobs on the cloud server run restore scripts: containers are updated and the database is restored 3. **Failover** - If the local server is online, Cloudflare load balances traffic - If the local server is offline, traffic automatically switches to the cloud server without manual intervention 4. **Cloud Management** - Portainer for Docker management - Fail2Ban and basic hardening for security ### When the Local Container Is UP: ✅ Handles normal requests ### When the Local Container Is DOWN: ✅ Cloudflare redirects requests to the cloud VM ✅ The site remains online, services continue to function ## Tutorial: ## OnPremise: #### a) Backup of Docker Volumes of Web Servers For each dockerized service (like NGINX or others), I create a backup of the volumes using a temporary Alpine container. At the end, everything is transferred to the cloud via **SCP**. Example — **Web Server Example**: ```plaintext #!/bin/bash DATE=$(date +"%Y%m%d-%H%M") BACKUP_DIR="/root/backups" CLOUD_USER="insert_username" CLOUD_IP="insert_cloud_ip" SSH_KEY="insert_ssh_key" REMOTE_PATH="/home/insert_username/webserver_backup_${DATE}.tar.gz" mkdir -p ${BACKUP_DIR} cd ${BACKUP_DIR} # Backup Docker volumes docker run --rm -v insert_volume_id1:/volume -v $(pwd):/backup alpine sh -c "cd /volume && tar czf /backup/nginx_backup.tar.gz ." docker run --rm -v insert_volume_id2:/volume -v $(pwd):/backup alpine sh -c "cd /volume && tar czf /backup/html_backup.tar.gz ." # Create a single archive and transfer to the cloud tar czf webserver_backup_${DATE}.tar.gz nginx_backup.tar.gz html_backup.tar.gz scp -i ${SSH_KEY} webserver_backup_${DATE}.tar.gz ${CLOUD_USER}@${CLOUD_IP}:${REMOTE_PATH} rm -f nginx_backup.tar.gz html_backup.tar.gz ``` * * * ### b) WordPress Database Dump I execute a SQL dump from the MySQL/MariaDB container and transfer it to the cloud: ```plaintext #!/bin/bash DATE=$(date +"%Y%m%d-%H%M") LOCAL_DUMP="/root/wordpress_db_backup_${DATE}.sql" CLOUD_USER="insert_username" CLOUD_IP="insert_cloud_ip" SSH_KEY="insert_ssh_key" DB_USER="insert_db_user" DB_PASS="insert_db_password" DB_NAME="insert_db_name" docker exec insert_container_name_db mysqldump --no-tablespaces -u ${DB_USER} -p"${DB_PASS}" ${DB_NAME} > ${LOCAL_DUMP} scp -i ${SSH_KEY} ${LOCAL_DUMP} ${CLOUD_USER}@${CLOUD_IP}:/home/insert_username/ ``` * * * ### c) Automation with Cronjob Example of crontab: `0 3 * * * /root/scripts/replica_webserver.sh 0 4 * * * /root/scripts/replica_wordpress.sh` ## Cloud: ### a) Restore of Web Server Volumes On the cloud, I unpack the received backups and restore them to Docker volumes: ```plaintext #!/bin/bash BACKUP_FILE=$(ls -t /home/insert_username/webserver_backup_*.tar.gz | head -n 1) RESTORE_DIR="/root/restore_temp" mkdir -p ${RESTORE_DIR} tar xzf ${BACKUP_FILE} -C ${RESTORE_DIR} docker run --rm -v insert_volume_id1:/data -v ${RESTORE_DIR}:/backup alpine sh -c "rm -rf /data/* && tar xzf /backup/nginx_backup.tar.gz -C /data" docker run --rm -v insert_volume_id2:/data -v ${RESTORE_DIR}:/backup alpine sh -c "rm -rf /data/* && tar xzf /backup/html_backup.tar.gz -C /data" rm -rf ${RESTORE_DIR} ``` * * * ### b) Restore of WordPress Database ```plaintext #!/bin/bash DUMP_PATH=$(ls -t /home/insert_username/wordpress_db_backup_*.sql | head -n 1) CONTAINER_DB="insert_container_name_db" DB_USER="insert_db_user" DB_PASS="insert_db_password" DB_NAME="insert_db_name" docker cp "$DUMP_PATH" "$CONTAINER_DB:/wordpress_db_backup.sql" docker exec -i "$CONTAINER_DB" mysql -u "$DB_USER" -p"$DB_PASS" "$DB_NAME" -e "SET FOREIGN_KEY_CHECKS=0;DROP TABLE IF EXISTS wp_commentmeta, wp_comments, wp_links, wp_options, wp_postmeta, wp_posts, wp_term_relationships, wp_terms, wp_term_taxonomy, wp_usermeta, wp_users;SET FOREIGN_KEY_CHECKS=1;" docker exec -i "$CONTAINER_DB" sh -c "mysql -u $DB_USER -p\"$DB_PASS\" $DB_NAME < /wordpress_db_backup.sql" ``` * * * ### c) Automation with Cronjob on Cloud Example of crontab: ```plaintext 0 5 * * * /root/scripts/restore_webserver.sh 0 6 * * * /root/scripts/restore_wordpress.sh ``` ## Cloudflare: On both machines (Proxmox and Cloud), I activate the Cloudflare tunnel: ```plaintext cloudflared service install insert_tunnel_token ``` ## Cloudflare automatically manages traffic based on the availability of the on-premises container or the cloud VM. On this page - [How Does My Solution Work?](#how-does-my-solution-work) - [Tutorial:](#tutorial) - [OnPremise:](#onpremise) - [Cloud:](#cloud) - [Cloudflare:](#cloudflare) - [Cloudflare automatically manages traffic based on the availability of the on-premises container or the cloud VM.](#cloudflare-automatically-manages-traffic-based-on-the-availability-of-the-on-premises-container-or-the-cloud-vm)