|Software development process|
|Paradigms and models|
|Methodologies and frameworks|
|Standards and BOKs|
DevOps (a clipped compound of development and operations) is a set of practices that emphasizes the collaboration and communication of both software developers and other information-technology (IT) professionals while automating the process of software delivery and infrastructure changes. It aims at establishing a culture and environment where building, testing, and releasing software can happen rapidly, frequently, and more reliably.
In traditional functionally separated organizations there is rarely cross-departmental integration of these functions with IT operations. DevOps promotes a set of processes and methods for thinking about communication and collaboration between development, QA, and IT operations.
At the Agile 2008 conference, Andrew Clay Shafer and Patrick Debois discussed "Agile Infrastructure". The term "DevOps" was popularized through a series of devopsdays starting in 2009 in Belgium. Since then, there have been devopsdays conferences held in many countries worldwide.
Jabbari et al. based on a review of definitions of DevOps from 238 papers formulated the following definition: "DevOps is a development methodology with a set of practices aimed at bridging the gap between Development and Operations, emphasizing communication and collaboration, continuous integration, quality assurance and delivery with automated deployment”
Because DevOps is a cultural shift and collaboration between development, operations and testing, there is no single DevOps tool, rather a set or “DevOps toolchain” consisting of multiple tools. Generally, DevOps tools fit into one or more of these categories, which is reflective of the software development and delivery process:
- Code – Code development and review, Version control tools, code merging
- Build – continuous integration tools, build status
- Test – Test and results determine performance
- Package – Artifact repository, application pre-deployment staging
- Release – Change management, release approvals, release automation
- Configure – Infrastructure configuration and management, Infrastructure as Code tools
- Monitor – Applications performance monitoring, end user experience
Though there are many tools available, certain categories of them are essential in the DevOps toolchain setup for use in an organization. Some attempts to identify those basic tools can be found in the existing literature.
Tools such as Docker (containerization), Jenkins (continuous Integration), Puppet (Infrastructure as Code) and Vagrant (virtualization platform) among many others are often used and frequently referenced in DevOps tooling discussions.
Relationship to agile and continuous delivery
Agile and DevOps are similar, but while agile software development represents a change in thinking and practice that should lead to organizational change, DevOps places more emphasis on implementing change to achieve its goals. The need for DevOps was born from the increasing popularity of agile software development, as that tends to lead to an increased number of releases. One goal of DevOps is to establish an environment where releasing more reliable applications faster and more frequently can occur. Release managers are beginning to utilize tools such as application release automation and continuous integration tools to help advance this goal, doing so through the continuous delivery approach.
Continuous delivery and DevOps are similar in their meanings and are often conflated, but they are two different concepts. DevOps has a broader scope, and centers around the organizational change, specifically the collaboration of the various teams involved in software delivery (developers, operations, quality assurance, management, etc.), as well as automating the processes in software delivery. Continuous Delivery, on the other hand, is an approach to automate the delivery aspect, and focuses on bringing together different processes and executing them more quickly and more frequently. They have common end goals and are often used in conjunction to achieve them. DevOps and Continuous Delivery share a background in agile methods and lean thinking: small and quick changes with focused value to the end customer. They are well communicated and collaborated internally, thus helping achieve quick time to market, with reduced risks.
The specific goals of DevOps span the entire delivery pipeline. They include improved deployment frequency, which can lead to faster time to market, lower failure rate of new releases, shortened lead time between fixes, and faster mean time to recovery in the event of a new release crashing or otherwise disabling the current system. Simple processes become increasingly programmable and dynamic, using a DevOps approach. DevOps aims to maximize the predictability, efficiency, security, and maintainability of operational processes. Very often, automation supports this objective.
DevOps integration targets product delivery, continuous testing, quality testing, feature development, and maintenance releases in order to improve reliability and security and provide faster development and deployment cycles. Many of the ideas (and people) involved in DevOps came from the enterprise systems management and agile software development movements.
DevOps aids in software application release management for an organization by standardizing development environments. Events can be more easily tracked as well as resolving documented process control and granular reporting issues. The DevOps approach grants developers more control of the environment, giving infrastructure more application-centric understanding.
Benefits of DevOps
Companies that practice DevOps have reported significant benefits, including significantly shorter time-to-market, improved customer satisfaction, better product quality, more reliable releases, improved productivity and efficiency, and the increased ability to build the right product by fast experimentation.
DevOps is more than just a tool or a process change; it inherently requires an organizational culture shift. This cultural change is especially difficult because of the conflicting nature of departmental roles. Operations seeks organizational stability; developers seek change; and testers seek risk reduction. Getting these groups to work cohesively is a critical challenge in enterprise DevOps adoption.
Building a DevOps culture
DevOps principles demand strong interdepartmental communication, and team-building and other employee engagement activities are often used to create an environment that fosters this communication and cultural change within an organization. Team-building activities can include board games, trust activities, and employee engagement seminars.
Companies with very frequent releases may require a DevOps awareness or orientation program. For example, the company that operates the image hosting website Flickr developed a DevOps approach to support a business requirement of ten deployments per day; this daily deployment cycle would be much higher at organizations producing multi-focus or multi-function applications. This is referred to as continuous deployment or continuous delivery and has been associated with the lean startup methodology. Working groups, professional associations and blogs have formed on the topic since 2009.
DevOps and architecture
To practice DevOps effectively, software applications have to meet a set of Architecturally Significant Requirements (ASRs) such as deployability, modifiability, testability, and monitorability. These ASRs require a high priority and cannot be traded off lightly.
Although in principle it is possible to practice DevOps with any architectural style, the microservices architectural style is becoming the standard for building continuously deployed systems. Because the size of each service is small, it allows the architecture of an individual service to emerge through continuous refactoring, hence reduces the need for a big up front design and allows for releasing the software early and continuously.
Scope of adoption
Some articles in the DevOps literature assume, or recommend, significant participation in DevOps initiatives from outside an organization's IT Department, e.g.: "DevOps is just the Agile principle taken to the full enterprise." An example of such broader participation is this recommended change to internal funding processes: "Funding is typically provided in a waterfall manner, with specific hard dates (months, quarters, fiscal year) and gates, not suitable for a Continuous Delivery model. Funding too should be continuous."
Adoption of DevOps is being driven by many factors including:
- Use of agile and other development processes and methods
- Demand for an increased rate of production releases from application and business unit stakeholders
- Wide availability of virtualized and cloud infrastructure from internal and external providers
- Increased usage of data center automation and configuration management tools
- Increased focus on test automation and continuous integration methods
- A critical mass of publicly available best practices
The Theory of Constraints applies to the adaptation of DevOps – the single constraint is the inherent aversion to change from departments within the enterprise. Incremental adoption embodies the methodology the Theory of Constraints provides for combating any constraint, known as “The five focusing steps”.
The Incremental approach centers around the idea of minimizing risk and cost of a DevOps Adoption whilst building the necessary in-house skillset and momentum needed to have widespread successful implementation across the enterprise. Gene Kim’s Three Ways Principles essentially establishes different ways of incremental DevOps adoption.
The First Way: Systems Thinking
The emphasis is on the performance of the entire system, as opposed to the performance of a specific or single department or individual. Focus is also on all business value streams that are enabled by IT. This process works in a linear fashion ensuring that defects are never passed along.
The Second Way: Amplify Feedback Loops
The emphasis is on increasing feedback and understanding of all teams involved. The outcomes of this will be increased communication and responding to all customers, internal and external, shortening and amplifying all feedback loops, and embedding knowledge where and to whom it’s needed.
The Third Way: Culture of Continual Experimentation and Learning
Two things are equally important: experimentation and practice. Embedding this in the working culture - where learning from taking risks, and repetition and practice are encouraged - is key to mastery. Risk taking and experimentation promote improvement, whilst mastery provides the skills required to revert any mistakes.
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