> ## Documentation Index
> Fetch the complete documentation index at: https://docs.idocs.fyi/llms.txt
> Use this file to discover all available pages before exploring further.

# Docker Setup on Linux

> Installing Docker on Linux is a straightforward process, but the steps vary slightly depending on which distribution (distro) you are using. The most common method is using the official Docker repository to ensure you get the latest version.

## 1. Prerequisites

Before starting, uninstall any old versions of Docker (like `docker`, `docker.io`, or `docker-engine`) to avoid conflicts:

```
sudo apt-get remove docker docker-engine docker.io containerd runc
```

## 2. Installation on Ubuntu / Debian

Ubuntu is the most popular platform for Docker. Here is how to set it up:

### Step 1: Update and Install Dependencies

```
sudo apt update
sudo apt install ca-certificates curl gnupg lsb-release
```

### Step 2: Add Docker’s Official GPG Key

This ensures the software you're downloading is authentic.

```
sudo mkdir -p /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
```

### Step 3: Set up the Repository

```
echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu \
  $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
```

### Step 4: Install Docker Engine

```
sudo apt update
sudo apt install docker-ce docker-ce-cli containerd.io docker-compose-plugin
```

## 3. Installation on CentOS / RHEL

For Red Hat-based systems, use the `yum-utils` package.

1. **Install yum-utils:** `sudo yum install -y yum-utils`
2. **Add Repo:** `sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo`
3. **Install:** `sudo yum install docker-ce docker-ce-cli containerd.io`
4. **Start Docker:** `sudo systemctl start docker`

## 4. Post-Installation Steps (Important)

By default, you need `sudo` to run Docker commands. To run Docker as a non-root user, add your user to the `docker` group:

1. **Create the group:** `sudo groupadd docker` (usually already exists).
2. **Add your user:** `sudo usermod -aG docker $USER`
3. **Apply changes:** Log out and log back in, or run `newgrp docker`.

### Verify the Installation

Run the "hello-world" image to make sure everything is working:

```
docker run hello-world
```