Progressive delivery (blue-green, rolling updates, canaries, etc.) is a set of deployment practices that aim at rolling out new features gradually.
This time I will not write a lenghtly post. Instead, I'll try to explain different deployment strategies through diagrams. This is for all those who dislike black and white terminal and prefer colors, boxes, and lines with arrows.
The deployment strategies are not presented in any particular order.
I am continuously getting questions about blue-green releases inside a Docker Swarm cluster. Viktor, in your The DevOps 2.0 Toolkit book you told us to use blue-green deployment. How do we do it with services running inside a Swarm cluster? My answer is usually something along the following lines. With the old Swarm, blue-green releases were easier than rolling updates (neither were supported out of the box). Now we got rolling updates. Use them! The reaction to that is often that we still want blue-green releases.
This post is my brainstorming on this subject. I did not write it as a result of some deep thinking. There is no great wisdom in it. I just wrote what was passing through my mind while I was trying to answer another one of the emails containing blue-green deployment questions. What follows might not make much sense. Don't be harsh on me.
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.
- Blue-green deployment
- Relative scaling
- Proxy reconfiguration
Traditionally, we deploy a new release by replacing the current one. The old release is stopped, and the new one is brought up in its place. The problem with this approach is the downtime occurring from the moment the old release is stopped until the new one is fully operational. No matter how quickly you try to do this process, there will be some downtime. That might be only a millisecond, or it can last for minutes or, in extreme situations, even hours. Having monolithic applications introduces additional problems like, for example, the need to wait a considerable amount of time until the application is initialized. People tried to solve this issue in various ways, and most of them used some variation of the blue-green deployment process. The idea behind it is simple. At any time, one of the releases should be running meaning that, during the deployment process, we must deploy a new release in parallel with the old one. The new and the old releases are called blue and green.
Today is an exciting day for me. I just decided that the book I spent the last eight months writing is ready for general public.
What made me write the book? Certainly not the promise of wealth since, as any author of technical books will confirm, there is no money that can compensate the number of hours involved in writing a technical book. The reasons behind this endeavor are of a different nature. I realized that this blog is a great way for me to explore different subjects and share my experience with the community. However, due to the format, blog posts do not give enough space to explore, in more details, subjects I'm passionate about so, around eight months ago, I decided to start working on The DevOps 2.0 Toolkit: Automating the Continuous Deployment Pipeline with Containerized Microservices book. It treats similar subjects as those I write about in this blog, but with much more details. More importantly, the book allowed me to organize my experience into a much more coherent story.
The book is about different techniques that help us architect software in a better and more efficient way with microservices packed as immutable containers, tested and deployed continuously to servers that are automatically provisioned with configuration management tools. It's about fast, reliable and continuous deployments with zero-downtime and ability to roll-back. It's about scaling to any number of servers, designing self-healing systems capable of recuperation from both hardware and software failures and about centralized logging and monitoring of the cluster.
In other words, this book envelops the whole microservices development and deployment lifecycle using some of the latest and greatest practices and tools. We'll use Docker, Kubernetes, Ansible, Ubuntu, Docker Swarm and Docker Compose, Consul, etcd, Registrator, confd, Jenkins, and so on. We'll go through many practices and, even more, tools.
At this moment, around 70% is finished and you'll receive regular updates if you decide to purchase the book. The truth is that my motivation for writing the book is the same as with this blog. I like sharing my experience and this book is one more way to accomplish that. You can set your own price and if you feel that the minimum amount is still too high, please send me a private message and I'll get back to you with a free copy.
Please give The DevOps 2.0 Toolkit: Automating the Continuous Deployment Pipeline with Containerized Microservices a try and let me know what you think. Any feedback is welcome and appreciated.
The idea behind this article is to explore ways to deploy releases with Jenkins to Docker Swarm without downtime. We'll use blue-green procedure. More info about the process and one possible implementation can be found in the Blue-Green Deployment, Automation and Self-Healing Procedure article. One of the downsides of the process we used in that article is Ansible itself. While it is probably the best tool for provisioning and orchestration, it had some downsides when we tried to use it as the tool to deploy containers. This is especially evident when the process is complex. Ansible lacks some constructs common in most programming languages. This time we'll try to implement the same process but using the Jenkins Workflow Plugin that was developed and contributed to Jenkins open source project by CloudBees.