Service Discovery Inside A Docker Swarm Cluster

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The text that follows contains excerpts from the Service Discovery Inside A Swarm Cluster chapter of the The DevOps 2.1 Toolkit: Docker Swarm book.

Service Discovery In The Swarm Cluster

The old (standalone) Swarm required a service registry so that all its managers can have the same view of the cluster state. When instantiating the old Swarm nodes, we had to specify the address of a service registry. However, if you take a look at setup instructions of the new Swarm (Swarm Mode introduced in Docker 1.12), you’ll notice that we nothing is required beyond Docker Engines. You will not find any mention of an external service registry or a key-value store.
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The DevOps Toolkit Series Are Born

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The DevOps 2.1 ToolkitAt the beginning of 2016, I published The DevOps 2.0 Toolkit. It took me a long time to finish it. Much longer than I imagined.

I started by writing blog posts in TechnologyConversations.com. They become popular and I received a lot of feedback. Through them, I clarified the idea behind the book. The goal was to provide a guide for those who want to implement DevOps practices and tools. At the same time, I did not want to write a material usable to any situation. I wanted to concentrate only on people that truly want to implement the latest and greatest practices. I hoped to make it go beyond the “traditional” DevOps. I wished to show that the DevOps movement matured and evolved over the years and that we needed a new name. A reset from the way DevOps is implemented in some organizations. Hence the name, The DevOps 2.0 Toolkit.
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Distributed Application Bundles (Tour Around Docker 1.12 Series)

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The new Swarm bundled in Docker 1.12+ is a vast improvement compared to the old orchestration and scheduling. There is no more the need to run a separate set of Swarm containers (it is bundled in Docker Engine), failover strategies are much more reliable, service discovery is baked in, the new networking works like a charm, and so on. The list of features and improvements is quite big. If you haven’t had a chance to give it a spin, please read the Docker Swarm Introduction and Integrating Proxy With Docker Swarm.

In those articles we used commands to run Docker services inside the Swarm cluster. If you are like me, you are probably used to the simplicity Docker Compose provides. Instead trying to memorize commands with all the arguments required for running services, you probably specified everything as Docker Compose files and run containers with a simple docker-compose up -d command. After all, that is much more convenient than docker service create followed by an endless number of arguments. My brain does not have the capacity to memorize all of them.

When I started “playing” with the new Swarm, my first impression was this is great, followed by I don’t want to memorize different arguments for all of my services. I want my Compose files back into the game.
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Integrating Proxy With Docker Swarm (Tour Around Docker 1.12 Series)

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Docker Swarm

This article continues where Docker Swarm Introduction left. I will assume that you have at least a basic knowledge how Swarm in Docker v1.12+ works. If you don’t, please read the previous article first.

The fact that we can deploy any number of services inside a Swarm cluster does not mean that they are accessible to our users. We already saw that the new Swarm networking made it easy for services to communicate with each other.

Let’s explore how we can utilize it to expose them to the public. We’ll try to integrate a proxy with the Swarm network and further explore benefits version v1.12 brought.
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Docker Swarm Introduction (Tour Around Docker 1.12 Series)

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Docker SwarmDocker just published a new Docker Engine v1.12. It is the most significant release since v1.9. Back then, we got Docker networking that, finally, made containers ready for use in clusters. With v1.12, Docker is reinventing itself with a whole new approach to cluster orchestration. Say goodbye to Swarm as a separate container that depends on an external data registry and welcome the new Docker Swarm. Everything you’ll need to manage your cluster is now incorporated into Docker Engine. Swarm is there. Service discovery is there. Improved networking is there.
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Docker Networking and DNS: The Good, The Bad, And The Ugly

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Docker SDN (Software Defined Network) already exists for quite some time. What is new, starting from the release 1.11, is the addition of DNS round-robin load balancing. That is both a reason for celebration and an opportunity to explore Docker networking and DNS. We’ll explore internal and external networking, see how DNS fits into the picture, discuss use cases that might be a good fit, and finish with pros and cons.
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Docker Flow – Walkthrough

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Docker Flow is a project aimed towards creating an easy to use continuous deployment flow. It depends on Docker Engine, Docker Compose, Consul, and Registrator. Each of those tools is proven to bring value and are recommended for any Docker deployment.

The goal of the project is to add features and processes that are currently missing inside the Docker ecosystem. The project, at the moment, solves the problems of blue-green deployments, relative scaling, and proxy service discovery and reconfiguration. Many additional features will be added soon.

The current list of features is as follows.