How to write a startup script for your Ubuntu containers:

To create an Ubuntu bash script that starts Docker containers automatically after a server power restart, you can follow these steps:

1. Create a new bash script file, for example start_containers.sh:

#!/bin/bash
set -eou pipefail

# Log file for debugging
LOG_FILE="/var/log/docker_startup.log"

# Function to log messages
log_message() {
    echo "$(date): $1" >> "$LOG_FILE"
}

# Wait for Docker to start
while ! docker info >/dev/null 2>&1; do
    log_message "Waiting for Docker to start..."
    sleep 5
done

log_message "Docker is running. Starting containers..."

# Start your containers here
docker start container1
docker start container2
docker start container3

# Or use docker-compose if you have a docker-compose.yml file
# cd /path/to/your/docker/compose/directory
# docker-compose up -d

log_message "Containers started successfully"

2. Make the script executable:

chmod +x start_containers.sh

3. To ensure this script runs automatically after a server restart, you can create a systemd service. Create a new file named docker-startup.service in /etc/systemd/system/:

sudo nano /etc/systemd/system/docker-startup.service

4. Add the following content to the file:

[Unit]
Description=Start Docker containers after boot
After=docker.service
Requires=docker.service

[Service]
Type=oneshot
ExecStart=/path/to/your/start_containers.sh
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target

5. Save the file and exit the editor.
6. Reload the systemd daemon to recognize the new service:

sudo systemctl daemon-reload

7. Enable the service to run at boot:

sudo systemctl enable docker-startup.service

8. You can start the service manually to test it:

sudo systemctl start docker-startup.service

This script and systemd service will:

• Wait for the Docker daemon to start before attempting to start containers
• Log its actions to a file for debugging purposes
• Start your specified containers or run docker-compose
• Run automatically after each system reboot

Remember to replace container1, container2, etc., with your actual container names or use docker-compose commands if you prefer that method[2][3][4].

By using this approach, you ensure that your Docker containers start automatically after a server reboot, without relying on Docker’s built-in restart policies. This gives you more control over the startup process and allows for additional logic if needed[5].

Citations:
[1] https://help.ubuntu.com/community/Beginners/BashScripting
[2] https://www.reddit.com/r/selfhosted/comments/ovr175/how_do_you_auto_recreate_docker_containers_on/
[3] https://betterstack.com/community/questions/how-to-start-docker-containers-automatically-after-reboot/
[4] https://www.digitalocean.com/community/questions/how-to-start-docker-containers-automatically-after-a-reboot
[5] https://supportfly.io/docker-restart-policy/
[6] https://www.warp.dev/terminus/docker-run-bash
[7] https://stackoverflow.com/questions/30449313/how-do-i-make-a-docker-container-start-automatically-on-system-boot
[8] https://docs.docker.com/engine/containers/start-containers-automatically/
[9] https://jugmac00.github.io/blog/how-to-run-a-dockerized-service-via-systemd/