# install-docker.sh — Docker installer script

## Purpose
- Installs Docker Engine, CLI, containerd and Compose plugin across common Linux distributions (Ubuntu/Debian, CentOS/RHEL, Fedora, Alpine, Arch).

## Requirements
- A Linux system with one of the supported distributions.
- `sudo` privileges for the user running the script.
- Internet access to download packages from Docker repositories.

## Usage
1. Make the script executable (if not already):

```bash
chmod +x install-docker.sh
```

2. Run the script as your normal user (you will be prompted for sudo):

```bash
./install-docker.sh
```

The script detects your OS via `/etc/os-release` and runs the appropriate package commands.

## Post-install steps
- The script enables and starts the Docker service via `systemctl`.
- It also adds the current user to the `docker` group. You may need to log out and log back in (or run `newgrp docker`) to use Docker without `sudo`.

## Notes & Troubleshooting
- Unsupported OS: the script exits with an error if the distribution is not recognized.
- On systems without `systemd` (or where `systemctl` is unavailable), service start/enable will fail—start Docker manually as appropriate for your init system.
- If package repository GPG fetch or keyring operations fail, verify network access and that `curl`/`gnupg` are present.
- The script assumes typical package managers: `apt`, `yum`, `dnf`, `apk`, or `pacman`.

## Example
```bash
# Run installer (prompts for sudo)
./install-docker.sh

# Verify Docker
docker --version
sudo systemctl status docker
```

## Security
- The script adds official Docker package repositories and installs upstream packages. Review the commands if you have custom security requirements.

## Contributing / Changes
- To adapt the script for additional distributions or custom mirrors, add/modify the `case` branches that handle installation for each `OS`.

## License
- No license included. If you want this README or script under a specific license, add a LICENSE file.