sync_containers.info

Let’s break down what this script does in detail. The script is named sync_containers.sh, authored by GJS (homelab-alpha), and its purpose is to synchronize Docker container images from a predefined list, validate container labels, and perform system disk space checks. It also logs all actions and errors to a log file.

Script Metadata link

• Filename: sync_containers.sh
• Author: GJS (homelab-alpha)
• Date: February 23, 2025
• Version: 1.0.0
• Description: Synchronizes Docker container images from a predefined list, validates container formats, checks system disk space, and logs the actions.
• RAW Script: sync_containers.sh

Script Header link

The script starts with a metadata section, including the author, version, description, and usage instructions. It also provides information about available options and necessary dependencies.

Requirements link

Before running the script, ensure the following dependencies are available on your system:

• Docker: Required for managing and pulling container images.
• Disk space validation: Ensures sufficient space to download Docker containers.
• Log directory: Automatically created if it does not already exist.

Usage link

Command-Line Usage link

The script can be executed directly with the following command structure:

./sync_containers.sh [options]

Options link

• --update: Synchronize Docker containers.
• --info: Display current system and Docker information.
• -h, --help: Show the help menu.
• -q, --quit: Exit the script.

Examples link

1. Synchronize Docker containers:

   ./sync_containers.sh --update
   

2. Display system and Docker information:

   ./sync_containers.sh --info
   

3. Show help menu:

   ./sync_containers.sh --help
   

4. Exit the script:

   ./sync_containers.sh --quit
   

Main Menu link

Upon execution, the script displays an interactive menu, offering the following options:

1. Synchronize Docker containers.
2. Display Docker and system information.
3. Exit the script.

Additionally, users can interact with the following shortcuts:

• -h or --help: Show the help menu.
• -q or --quit: Exit the script.

Synchronization Process link

The synchronization process consists of the following key steps:

1. Disk Space Check: Verifies available disk space before attempting to pull images.
2. Container Format Validation: Checks each container image against a regular expression to ensure correct format.
3. Pull Docker Images: Attempts to pull each Docker image from the list. Success or failure is logged.
4. Logging: All actions, successes, and failures are logged to a file (sync_containers.log).
5. Summary Report: After synchronization, the script provides a summary of the success, failure, and invalid pulls.

Example Output link

Starting Docker container synchronization...
Pulling amir20/dozzle:latest...
Success: amir20/dozzle:latest pulled successfully.
Pulling containrrr/watchtower:latest...
Error: Failed to pull containrrr/watchtower:latest.
Detailed error for containrrr/watchtower:latest:
<docker pull error log>

Summary:
 - Successful pulls: 10
 - Failed pulls: 2
 - Invalid labels: 0

Synchronization completed!

Handling User Input link

Upon running the script, users are prompted with the following options:

• Option 1: Synchronize Docker containers (--update).
• Option 2: View system and Docker information (--info).
• Option 3: Exit the script (--quit).

If the user selects an invalid option, the script will ask them to choose again.

Functions link

Display Help Message link

The display_help() function provides a detailed guide on script options and usage.

display_help() {
  clear
  echo "================================================================================"
  echo "                   Docker Container Sync Tool - Help                            "
  echo "================================================================================"
  echo
  echo "Usage:"
  echo "  ./sync_containers.sh [options]"
  echo
  echo "Options:"
  echo "  1. --update   : Synchronize Docker containers"
  echo "  2. --info     : Show current user's system and Docker information."
  echo "  h, --help     : Display this help message."
  echo "  q, --quit     : Exit the script."
  echo
  echo "Description:"
  echo "  This script helps you synchronize Docker container images from a"
  echo "  predefined list. It validates container labels, checks disk space,"
  echo "  and ensures Docker and network connectivity before pulling the images."
  echo
  echo "================================================================================"
}

Display System and Docker Information link

The display_info() function provides system details, Docker status, and available disk space.

display_info() {
  clear
  echo "================================================================================"
  echo "                  Docker User and System Information                            "
  echo "================================================================================"
  echo
  echo "Current User Information:"
  echo "User  ID (PUID): $(id -u)"
  echo "Group ID (PGID): $(id -g)"
  echo

  echo "Install Check List:"
  if command -v docker &>/dev/null; then
    docker_version=$(docker --version)
    echo "$docker_version"
  else
    echo "Docker: Not installed"
  fi

  if command -v docker compose &>/dev/null; then
    docker_compose_version=$(docker compose version)
    echo "$docker_compose_version"
  else
    echo "Docker Compose: Not installed"
  fi

  echo
  echo "System Disk Space:"
  df -h | grep -E '^/dev/|^Filesystem'
  echo
  echo "================================================================================"
}

Synchronize Docker Containers link

The sync_containers() function handles the synchronization by validating formats, checking disk space, and pulling the images.

sync_containers() {
  if [[ -z "${CONTAINERS+x}" || -z "$log_file" ]]; then
    echo "Error: CONTAINERS array or log file path is not defined."
    return 1
  fi

  echo "Starting Docker container synchronization..."
  success_count=0
  fail_count=0
  invalid_count=0

  for container in "${CONTAINERS[@]}"; do
    if [[ "$container" =~ ^[a-zA-Z0-9_.-]+(/?[a-zA-Z0-9_.-]+)+(:[a-zA-Z0-9_.-]+)?$ ]]; then
      echo "Pulling $container..."
      if docker pull "$container" &>>"$log_file"; then
        ((success_count++))
        echo "Success: $container pulled successfully."
      else
        ((fail_count++))
        echo "Error: Failed to pull $container."
        echo "Detailed error for $container:" >> "$log_file"
        docker pull "$container" 2>> "$log_file"
      fi
    else
      ((invalid_count++))
      echo "Invalid container format: $container"
    fi
  done

  echo
  echo "Summary:"
  echo " - Successful pulls: $success_count"
  echo " - Failed pulls: $fail_count"
  echo " - Invalid labels: $invalid_count"
  echo
  echo "Synchronization completed!"
}

Command-Line Option Parsing link

The main loop processes user input and executes the appropriate action (synchronizing containers, displaying system info, or quitting).

while true; do
  clear
  echo "================================================================================"
  echo "                           Docker Container Sync Tool                           "
  echo "================================================================================"
  echo
  echo "Please choose an option:"
  echo
  echo "   1. Synchronize Docker containers"
  echo "   2. Display Docker and system information"
  echo
  echo "   q: quit   h: help"
  echo "================================================================================"
  echo
  read -r -p "Please select an option (1, 2, h, or q to exit): " choice

  case $choice in
  1 | --update)
    echo "Starting synchronization of Docker containers..."
    sync_containers
    break
    ;;
  2 | --info)
    display_info
    echo
    read -n 1 -s -r -p "Press any key to continue..."
    continue
    ;;
  h | --help)
    display_help
    echo
    read -n 1 -s -r -p "Press any key to continue..."
    continue
    ;;
  q | --quit)
    echo "Exiting the script. Goodbye!"
    exit 0
    ;;
  *)
    echo "Error: Invalid option. Please try again."
    ;;
  esac
done

Conclusion link

The sync_containers.sh script simplifies Docker container synchronization, ensuring proper disk space, format validation, and error logging. It is a helpful tool for automating Docker container management tasks, making it ideal for Docker administrators or anyone managing containerized applications.