Docker Swarm has seen enormous traction in the container orchestration space since it makes managing your containers so much easier. With Swarm, you can use many different container managers, and teams can also share containers while moving them between containers in clusters. It integrates very well with Kubernetes and Mesosphere DC/OS, helping you to create an excellent container orchestration platform.
Using Docker Swarm with Kubernetes in a "plus" configuration is possible as Kubernetes works as an overlay on top of Swarm. This technique might take some getting used to, and I suggest you read through the Kubernetes documentation first.
Docker Swarm is especially popular with Docker users, so we thought it would be interesting to explore Swarm's top 5 features.
#1 – Installation and Setup
We are used to installing software by clicking a button on the internet or manually running commands on the command line. With Docker Swarm, there is a much more streamlined installation process, which we'll discuss here.
Docker for Windows users can automatically install Docker Swarm by running the following command:
docker swarm init one docker swarm init
Docker for MacOS can also install Swarm directly by running the following command:
docker run -d -p 8080:8080 \ -e CURL_FLUSH_READS -e CURL_FLUSH_EXTS \ -v $(PWD):/docker-swarm/swarm.yml:/swarm.yml \ gcenter
Once installed, you will have to set the Swarm information file in the cluster root directory:
docker run --rm --link docker://docker/swarm-stats -v $(PWD):/docker-swarm/swarm.yml:/swarm.yml \ --name swarm-stats 1 docker run -- rm -- link docker : / swarm - stats
This set of commands will run the configuration tool to collect information about the cluster and your containerized applications. You can then launch the Swarm Dashboard to view the stats for the cluster, see what is currently running and see your containers.
Once the Dashboard is running, click on your docker.com domain in the upper left corner, and you will be taken to the Swarm dashboard.
#2 – Configuration
If you already have a working Kubernetes cluster, you can continue to work with it directly in the UI. For new clusters that are started, you can use the following Swarm Command to create a new "master" cluster:
docker swarm create --name master-1 1 docker swarm to create -- name master - 1
#3 – Replication Controller
The first job that Docker Swarm performs is to provide a set of replicas for your containers. The Replication Controller orchestrates this. It will then connect to the master and create a copy of your containers in a swarm state.
#4 – API Gateway
As you develop your application, you will have access to the cluster API directly from the CI/CD environment. Docker Swarm will work with this, allowing you to modify cluster state and monitor Docker Swarm metrics. For example, you can create a new state, spin up new containers, or switch between containers in the cluster state.
#5 – Storage
The next step is to install storage into your cluster. Swarm uses storage volumes for the state and pods of your containers.
To do this, you will use the Volume Manager for Swarm to connect directly to your cluster volumes.
Learn core Docker technologies such as Docker Hub, Docker Compose, Docker Swarn with the Docker Certified Associate Certification Training Course.
Summary
Docker Swarm provides an excellent toolset for deploying containerized applications into a production environment, and, in our experience, it works pretty well, even in production. To get started, visit the Docker website for instructions and the Docker API.
If you’re looking to improve your skills and knowledge of DevOps tools and technologies, Simplilearn has a number of courses and programs to help you. One such course is the Docker Certified Administrator (DCA) Certification course, which includes training in Docker Swarm. For a comprehensive program that covers a full spectrum of DevOps skills, consider the Post Graduate Program in DevOps, offered in collaboration with Caltech CTME. It includes the DCA certification course as well as Kubernetes certification, training in Chef, Ansible, and Puppet, and a portfolio-worth capstone project to demonstrate your new skills.
