How to Deploy Docker Swarm | Linux Installation Guide

Managing containers across various Linux servers at IOFLOOD is made easy through the installation of Docker Swarm. As we often utilize the service discovery, load balancing, and fault tolerance features, we’ve taken the time to compile our notes and tips into this comprehensive article. With our expertise, we aim to assit our dedicated cloud server hosting and fellow developers through installing and configuring Docker Swarm.

In this guide, we will navigate the process of installing Docker Swarm on your Linux system. We are going to provide you with installation instructions for Debian, Ubuntu, CentOS, and AlmaLinux, delve into how to compile Docker Swarm from the source, and install a specific version. Finally, we will show you how to use Docker Swarm and ascertain that the correctly installed version is in use.

Let’s get started with the step-by-step Docker Swarm installation on your Linux system!

TL;DR: How Do I Install Docker Swarm on Linux?

Docker Swarm is included with Docker. To install Docker on Debian-based distributions like Ubuntu, use the command sudo apt-get install docker-ce. For RPM-based distributions like CentOS, use the command sudo yum install docker-ce. You can then initialize Docker Swarm using sudo docker swarm init.

# Debian-based distributions
sudo apt-get install docker-ce

# RPM-based distributions
sudo yum install docker-ce

# Output:
# Docker will be installed along with Docker Swarm

This is a basic way to install Docker Swarm on Linux, but there’s much more to learn about installing and using Docker Swarm. Continue reading for more detailed information and advanced usage scenarios.

Getting Started with Docker Swarm

Docker Swarm is a container orchestration tool bundled with Docker. It allows you to manage multiple containers deployed across multiple host machines. This is especially useful when you’re dealing with complex applications that require various services running on different containers.

Installing Docker Swarm with APT

For Debian-based systems like Ubuntu, you can install Docker, which includes Docker Swarm, using the Advanced Package Tool (APT). Here’s how you can do it:

# Update your repository
sudo apt-get update

# Install Docker
sudo apt-get install docker-ce

# Verify Docker installation
sudo docker --version

# Output:
# Docker version 20.10.7, build f0df350

In the above example, we first updated the package repository using sudo apt-get update. Then, we installed Docker using sudo apt-get install docker-ce. Finally, we verified the Docker installation by checking its version with sudo docker --version. The output should show the installed version of Docker.

Installing Docker Swarm with YUM

For RPM-based systems like CentOS or Fedora, you can use the Yellowdog Updater, Modified (YUM) to install Docker. Here’s the step-by-step guide:

# Update your repository
sudo yum update

# Install Docker
sudo yum install docker-ce

# Start Docker
sudo systemctl start docker

# Enable Docker to start at boot
sudo systemctl enable docker

# Verify Docker installation
sudo docker --version

# Output:
# Docker version 20.10.7, build f0df350

In the above example, we first updated the package repository using sudo yum update. Then, we installed Docker using sudo yum install docker-ce. We started Docker using sudo systemctl start docker and enabled it to start at boot using sudo systemctl enable docker. Finally, we verified the Docker installation by checking its version with sudo docker --version. The output should show the installed version of Docker.

Initializing Docker Swarm

After installing Docker, you can initialize Docker Swarm using the following command:

# Initialize Docker Swarm
sudo docker swarm init

# Output:
# Swarm initialized: current node (dxn1zf6l61qsb1josjja83ngz) is now a manager.

In the above command, we initialized Docker Swarm using sudo docker swarm init. The output shows that Docker Swarm has been initialized and your node is now a manager.

Advanced Docker Swarm Features

Docker Swarm has a number of advanced features that make it a powerful tool for managing and scaling containerized applications. In this section, we’ll discuss how to create a Swarm, add nodes, and deploy services.

Creating a Swarm

A Swarm is a group of machines running Docker and joined into a cluster. After you have installed Docker, you can create a Swarm as follows:

# Create a Swarm
sudo docker swarm init

# Output:
# Swarm initialized: current node (dxn1zf6l61qsb1josjja83ngz) is now a manager.

In this example, we created a Swarm using the sudo docker swarm init command. The output indicates that the Swarm has been initialized and the current node is now a manager.

Adding Nodes to the Swarm

Once you have a Swarm, you can add nodes to it. Each node in the Swarm is either a manager node or a worker node. Here’s how you can add a worker node to the Swarm:

# On the worker node, run the following command
sudo docker swarm join --token SWMTKN-1-49nj1cmql0jkz5s954yi3oex3nedyz0fb0xx14ie39trti4wxv-8vxv8rssmk743ojnwacrr2e7c 192.168.99.100:2377

# Output:
# This node joined a swarm as a worker.

In this example, we added a worker node to the Swarm using the sudo docker swarm join --token command. Replace SWMTKN-1-49nj1cmql0jkz5s954yi3oex3nedyz0fb0xx14ie39trti4wxv-8vxv8rssmk743ojnwacrr2e7c with the token for your Swarm, and 192.168.99.100:2377 with the IP address and port of the manager node. The output indicates that the node has joined the Swarm as a worker.

Deploying Services to the Swarm

A service is the definition of the tasks to execute on the manager or worker nodes. It is the central structure of the Swarm system and the primary root of user interaction with the Swarm. Here’s how you can deploy a service to the Swarm:

# Create a service
sudo docker service create --replicas 1 --name helloworld alpine ping docker.com

# List the services running on the Swarm
sudo docker service ls

# Output:
# ID            NAME        MODE        REPLICAS  IMAGE
# 9uk4639qpg7n  helloworld  replicated  1/1       alpine:latest

In this example, we first created a service using the sudo docker service create --replicas 1 --name helloworld alpine ping docker.com command. This command creates a service named helloworld that runs the ping docker.com command on an alpine image. We then listed the services running on the Swarm using the sudo docker service ls command. The output shows the services running on the Swarm.

Other Container Orchestration Tools

While Docker Swarm is a powerful tool for managing containers, it’s not the only option out there. Kubernetes is another popular container orchestration tool that you might consider using. Let’s take a closer look at Kubernetes and how it compares to Docker Swarm.

Kubernetes: A Powerful Alternative

Kubernetes, also known as K8s, is a portable, extensible, open-source platform for managing containerized workloads and services. It’s designed to facilitate both declarative configuration and automation.

Here’s how you can install Kubernetes on Linux:

# Update your package lists for upgrades and new packages
sudo apt-get update

# Install Docker
sudo apt-get install docker.io

# Install Kubernetes
sudo apt-get install apt-transport-https
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
echo "deb http://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list
sudo apt-get update
sudo apt-get install -y kubeadm

# Output:
# Kubernetes will be installed

In the above example, we first updated the package repository using sudo apt-get update. Then, we installed Docker using sudo apt-get install docker.io. After that, we installed Kubernetes with a series of commands.

Docker Swarm vs Kubernetes

While both Docker Swarm and Kubernetes are powerful tools, they have their own strengths and weaknesses.

• Ease of Use: Docker Swarm is generally easier to set up and use than Kubernetes, which can be complex and difficult to master.

• Scalability: Kubernetes is more robust and better suited to large-scale, complex deployments than Docker Swarm.

• Community Support: Kubernetes has a larger community and more third-party integrations than Docker Swarm.

In conclusion, if you’re looking for a simple, straightforward tool for managing containers, Docker Swarm is a great choice. But if you need to manage large-scale, complex deployments, you might want to consider using Kubernetes instead.

Troubleshooting Docker Swarm

While installing Docker Swarm on Linux is generally straightforward, you may encounter some common issues. Let’s discuss these potential hurdles and how to overcome them.

Issue: Docker Command Not Found

After installing Docker, you may find that your system doesn’t recognize the docker command. This could be because the Docker binary isn’t in your system’s PATH.

# Try running Docker
docker --version

# Output:
# bash: docker: command not found

In the above example, we tried running docker --version, but the system didn’t recognize the docker command. The output shows the error message bash: docker: command not found.

Solution: Add Docker to your system’s PATH. You can do this by adding the following line to your ~/.bashrc or ~/.zshrc file: export PATH=/usr/local/bin:$PATH. Then, source your ~/.bashrc or ~/.zshrc file, or open a new terminal.

Issue: Docker Swarm Init Fails

When trying to initialize Docker Swarm with docker swarm init, you may encounter an error if Docker can’t determine which IP address to use.

# Try initializing Docker Swarm
sudo docker swarm init

# Output:
# Error response from daemon: could not choose an IP address to advertise since this system has multiple addresses

In the above example, we tried initializing Docker Swarm using sudo docker swarm init, but Docker couldn’t determine which IP address to use. The output shows the error message Error response from daemon: could not choose an IP address to advertise since this system has multiple addresses.

Solution: Specify an advertise address when you initialize Docker Swarm. You can do this with the --advertise-addr flag, like this: sudo docker swarm init --advertise-addr 192.168.99.100, replacing 192.168.99.100 with your IP address.

Container Orchestration Explained

Docker Swarm is a container orchestration tool, an essential part of managing and deploying applications in a Docker environment. But what does that mean, and why is it important? Let’s dive into the fundamentals of Docker Swarm and container orchestration.

Understanding Container Orchestration

In the world of software development, a container is a lightweight, standalone, and executable software package that includes everything needed to run a piece of software, including the code, a runtime, libraries, environment variables, and config files.

Container orchestration is the process of automating the deployment, scaling, networking, and availability of container-based applications. In other words, it’s about managing the lifecycles of containers, especially in large, dynamic environments.

# Start a Docker service
sudo docker service create --name my_service my_image

# Scale the service
sudo docker service scale my_service=5

# Output:
# my_service scaled to 5

In this example, we first created a Docker service using sudo docker service create --name my_service my_image. Then, we scaled the service to 5 instances using sudo docker service scale my_service=5. The output shows that the service has been scaled to 5 instances. This is a basic example of container orchestration, where we are managing the lifecycle of a container-based application.

The Role of Docker Swarm in Container Orchestration

Docker Swarm is a tool that allows IT administrators and developers to create and manage a cluster of swarm nodes within the Docker platform. It turns a pool of Docker hosts into a single, virtual Docker host, as Docker Swarm serves the standard Docker API. Any tool that works with a Docker daemon works equally well with a Docker Swarm.

Docker Swarm mode also offers features like service discovery and load balancing, secure by default with automatically generated certificates, overlay networks for containers, and easy scaling of services.

By understanding the fundamentals of Docker Swarm and container orchestration, you can better manage complex applications and ensure they run smoothly and efficiently.

Main Uses of Docker Swarm

Docker Swarm’s relevance extends beyond just managing containers on your local Linux machine. It plays a pivotal role in DevOps and cloud computing, two areas that have transformed the software development landscape.

Docker Swarm in DevOps

In the world of DevOps, Docker Swarm helps bridge the gap between development and operations. It allows developers to work in a standardized environment using containers, which can then be deployed and scaled seamlessly in a production environment. This leads to faster, more reliable deployments.

Docker Swarm and Cloud Computing

In cloud computing, Docker Swarm helps manage and scale applications across multiple cloud servers. This makes it easier to handle large-scale applications and traffic spikes. It also supports multi-cloud deployments, providing flexibility and preventing vendor lock-in.

Exploring Docker Compose and Docker Machine

Docker Compose and Docker Machine are two additional tools in the Docker ecosystem that can enhance your container management capabilities.

• Docker Compose is a tool for defining and running multi-container Docker applications. It uses a YAML file to configure your application’s services and creates and starts all services from your configuration with a single command.

• Docker Machine is a tool that lets you install Docker Engine on virtual hosts. These hosts can now be managed using docker-machine commands. You can use Machine to create Docker hosts on your local Mac or Windows box, on your company network, in your data center, or on cloud providers like Azure, AWS, or Digital Ocean.

Further Resources for Mastering Docker Swarm

To further your understanding of Docker Swarm and its applications in DevOps and cloud computing, consider checking out the following resources:

• Docker’s Official Documentation – The authoritative resource for Docker concepts, commands, and best practices.

• A Guide on Docker Swarm – Learn Docker Swarm through three distinct service categories.

• A Deep Dive into Docker Swarm – Step-by-step instructions for setting up a Docker Swarm cluster on DigitalOcean.

Recap: Docker Swarm Linux Guide

In this comprehensive guide, we’ve explored the ins and outs of installing and using Docker Swarm on Linux. Docker Swarm, a powerful tool for container orchestration, can greatly simplify the management and deployment of applications in a Docker environment.

We started with the basics, walking through the process of installing Docker Swarm on Linux, both for Debian-based distributions like Ubuntu and for RPM-based distributions like CentOS. We then delved into more advanced topics, such as creating a Swarm, adding nodes, and deploying services.

Along the way, we addressed common issues you might encounter during Docker Swarm installation and provided solutions to help you navigate these challenges. We also explored alternative approaches to container orchestration, specifically Kubernetes, giving you a sense of the broader landscape of container orchestration tools.

Here’s a quick comparison of Docker Swarm and Kubernetes:

Whether you’re just starting out with Docker Swarm or looking to level up your container orchestration skills, we hope this guide has given you a deeper understanding of Docker Swarm and its capabilities.

With its balance of ease of use and powerful features, Docker Swarm is a valuable tool for managing and scaling containerized applications on Linux. Happy orchestrating!