Docker - Basics

🐳 Docker – Basics

Docker is a tool that makes it easy to run applications in isolated environments called containers. It’s lightweight, fast, and very useful when dealing with blockchain nodes, APIs, or backend tools.

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🧠 What is Docker (In Simple Words)?

Think of Docker like a box.

• You put an app and everything it needs inside this box.

• You can send this box to any server.

• It will run exactly the same way everywhere.

This is helpful because:

• You don’t have to install dependencies manually.

• It avoids "works on my machine" problems.

• It saves time when setting up or migrating.

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🧰 Why Use Docker in Crypto?

In the crypto world, Docker is commonly used to:

• Run blockchain nodes (e.g. Ethereum, Cosmos, Aptos)

• Host explorers, RPC servers, or tooling

• Build reproducible environments for testnets

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⚙️ How to Install Docker on Ubuntu (VPS)

For Ubuntu 20.04 or 22.04, run the following steps:

# Update package list
sudo apt update

# Install Docker dependencies
sudo apt install -y apt-transport-https ca-certificates curl software-properties-common

# Add Docker’s official GPG key
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/trusted.gpg.d/docker.gpg

# Add Docker repo to APT sources
echo "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list

# Update package list again
sudo apt update

# Install Docker CE
sudo apt install -y docker-ce

# Enable Docker to start at boot
sudo systemctl enable docker
sudo systemctl start docker

# Check Docker version
docker --version

✅ Done! Docker is now installed and ready to use.

Optional: Add your user to the Docker group (to run docker without sudo):

sudo usermod -aG docker $USER

Then log out and log back in, or run newgrp docker.

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📦 Example: Running a Simple Container

Let’s try running an Ubuntu container:

docker run -it ubuntu

This will:

• Download the Ubuntu image (if not already downloaded)

• Start an interactive shell inside the container

You can now run Linux commands inside this isolated environment.

To exit: just type exit

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🧪 Example: Running a Blockchain Node with Docker

Here’s an example for running a Cosmos SDK chain node (e.g. Gaia):

docker run -it ghcr.io/cosmos/gaia:v23.2.0 gaiad version

You can also run full nodes with volume mounting and config, like:

docker run -d \
  --name gaiad-node \
  -v $HOME/.gaia:/root/.gaia \
  -p 26656:26656 \
  -p 26657:26657 \
  ghcr.io/cosmos/gaia:v23.2.0 \
  gaiad start

This will:

• Run the node in background (-d)

• Mount your config directory

• Expose the necessary ports

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🗑️ Cleaning Up Docker

To see running containers:

docker ps

To stop a container:

docker stop <container-id>

To remove a container:

docker rm <container-id>

To list all images:

docker images

To remove an image:

docker rmi <image-id>

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🧠 Summary

Term	Meaning
Container	A lightweight, isolated instance of an app
Image	The package used to create a container
Volume	A shared folder between your host and Docker
Docker Hub	Public repo of Docker images

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💡 Docker is a must-have tool for DevOps and node runners. Once you get used to it, it’ll save you hours of setup time.

Next → Learn how to run your validator in Docker or monitor logs inside containers.