The Continuous Integration process is the first two actions in the state-transition diagram. Which – if successful – kicks off the Continuous Delivery pipeline that implements the definition of done. Deployment is just one of the many actions that will have to be done continuously in this pipeline. Ideally, the process is automated from the point where the developer commits to the VCS to the point where the pipeline has confirmed that we have a valid release candidate.
Neither the question nor the answers really fit my simple way of thinking about it. Im a consultant and have synchronized these definitions with a number of Dev teams and DevOps people, but am curious about how it matches with the industry at large:
Zero. Nothing is automated when devs check in code… Youre lucky if they have compiled, run, or performed any testing prior to check-in.
EDIT: I would like to point out that theres a difference between the concept of “continuous delivery” as referenced in the first principle of the Agile Manifesto (http://agilemanifesto.org/principles.html) and the practice of Continuous Delivery, as seems to be referenced by the context of the question. The principle of continuous delivery is that of striving to reduce the Inventory waste as described in Lean thinking (http://www.miconleansixsigma.com/8-wastes.html). The practice of Continuous Delivery (CD) by agile teams has emerged in the many years since the Agile Manifesto was written in 2001. This agile practice directly addresses the principle, although they are different things and apparently easily confused.
“Continuous delivery is a software development methodology where the release process is automated. Every software change is automatically built, tested, and deployed to production. Before the final push to production, a person, an automated test, or a business rule decides when the final push should occur. Although every successful software change can be immediately released to production with continuous delivery, not all changes need to be released right away.
Continuous integration is a software development practice where members of a team use a version control system and integrate their work frequently to the same location, such as a master branch. Each change is built and verified by tests and other verifications in order to detect any integration errors as quickly as possible. Continuous integration is focused on automatically building and testing code, as compared to continuous delivery, which automates the entire software release process up to production.”
Atlassian posted a good explanation about Continuous integration vs. continuous delivery vs. continuous deployment:
Continuous Integration – is an automation to build and test application whenever new commits are pushed into the branch.
Continuous Delivery – is Continuous Integration + Deploy application to production by “clicking on a button” (Release to customers is often, but on demand).
Or more than several times per day. As often as any given discrete task is completed, basically. Consider for example a team of developers working on a single business application. In many environments, the following may happen:
These can lead to problems. Poor code/task organization leads to branching, branching leads to merging, merging… leads to suffering. Continuous integration as a practice addresses this by encouraging everybody to work from the same shared source. Individual work items should be discrete enough to be completed in a short amount of time (hours at most).
Basically the general idea is that integrating a small change in a small amount of work. Integrating a large change is a disproportionately large amount of work. The aggregate of integration work is smaller if done in constant small steps. This allows developers to spend more time working on business-visible features instead of development process overhead.
This follows the same idea of discrete, well defined work items. If theres a single master codebase which is only ever adjusted in small increments by complete, tested, known working features then that codebase is always stable. Automated testing is key here to be able to prove that stability at the push of a button.
The less stabilization work that needs to be done (which, again, is development process overhead and should be eliminated), the more often that codebase can be pushed to any given environment. In a lot of companies a deployment can be a pretty grueling process. Even a week-long all-hands-on-deck operation. This is expensive and produces no business value. By employing good work item definitions, effective automated testing, and continuous integration a team can be in a position to automate the codebases delivery to any given environment.
Youll rarely see this happen in a business environment, and its quite a joy when its encountered. If the codebase can be automatically tested and automatically deployed to any given environment then, well, production is an environment like any other. So if the team has built up to this point then theres a potential for significant value to the business by always being able to deploy updates to production.
Defect fixes are sent to customers faster, new features reach the market faster, new ideas are tested against the market in smaller increments to allow for redirection of priorities, etc.
For example, lets say a company has a big idea for a new feature in their software-based product or service. Theyve done some research, they know the market, and they believe this idea will result in a strong new line of revenue. Now consider two options for delivering that feature:
In the first scenario, if the feature doesnt have the desired market effect then a lot of money is wasted on something customers dont actually want. In the second scenario the fact that customers dont want it is determined much, much earlier and the rest of the work is de-prioritized.
Ultimately these “continuous things” are all about removing development process overhead. If a companys line of revenue is a particular service offering then ideally all of their costs should go into that offering. Development process overhead (merging code, re-testing the same features after a merge, manual deployment tasks, etc.) dont actually contribute to the value of the service, so these concepts seek to remove those costs from the process.
I think were over analyzing and maybe complicating a bit the “continuous” suite of words. In this context continuous means automation. For the other words attached to “continuous” use the English language as your translation guide and please dont try to complicate things!
In “continuous build” we automatically build (write/compile/link/etc) our application into something thats executable for a specific platform/container/runtime/etc.
“Continuous integration” means that your new functionality tests and performs as intended when interacting with another entity. Obviously, before integration takes place, the build must happen and thorough testing would also be used to validate the integration. So, in “continuous integration” one uses automation to add value to an existing bucket of functionality in a way that doesnt negatively disrupt the existing functionality but rather integrates nicely with it, adding a perceived value to the whole.
Integration implies, by its mere English definition, that things jive harmoniously so in code-talk my add compiles, links, tests and runs perfectly within the whole. You wouldnt call something integrated if it failed the end product, would you?!
In our context “Continuous deployment” is synonymous with “continuos delivery” since at the end of the day weve provided functionality to our customers. However, by overanalyzing this, I could argue that deploy is a subset of delivery because deploying something doesnt necessarily mean that we delivered. We deployed the code but because we havent effectively communicated to our stakeholders, we failed to deliver from a business perspective! We deployed the troops but we havent delivered the promised water and food to the nearby town.
What if I were to add the “continuous transition” term, would it have its own merit? After all, maybe its better suited to describe the movement of code through environments since it has the connotation of “from/to” more so than deployment or delivery which could imply one location only, in perpetuity! This is what we get if we dont apply common sense.
In conclusion, this is simple stuff to describe (doing it is a bit more …complicated!), just use common sense, the English language and youll be fine.
Continuous Integration: The practice of merging the development work with the main branch constantly so that the code has been tested as often as possible to catch issues early.
Continuous Delivery: Continuous delivery of code to an environment once the code is ready to ship. This could be staging or production. The idea is the product is delivered to a user base, which can be QAs or customers for review and inspection.
Unit test during the Continuous Integration phase can not catch all the bugs and business logic, particularly design issues that is why we need QA, or staging environment for testing.
Continuous Deployment: The deployment or release of code as soon as its ready. Continuous Deployment requires Continuous Integration and Continuous Delivery otherwise the code quality wont be guarantee in a release.
From what Ive learned with Alex Cowan in the course Continuous Delivery & DevOps, CI and CD is part of a product pipeline that consists in the time it goes from an Observations to a Released Product.
From Observations to Designs the goal is to get high quality testable ideas. This part of the process is considered Continuous Design.
What happens after, when we go from the Code onwards, its considered a Continuous Delivery capability whose aim is to execute the ideas and release to the customer very fast (you can read Jez Humbles book Continuous Delivery: Reliable Software Releases through Build, Test, and Deployment Automation for more details). The following pipeline explains which steps Continuous Integration (CI) and Continuous Delivery (CD) consist of.
(you can watch the following two videos for a more pratical overview using CircleCI – Getting started with CircleCI – Continuous Integration P2 and Running CircleCI on Pull Request).
One can specify the CI/CD pipeline as following, that goes from New Code to a released Product.
The first three steps have to do with Tests, extending the boundary of whats being tested.
Continuous Deployment, on the other hand, is to handle the Deployment automatically. So, any code commit that passes the automated testing phase is automatically released into the production.
Note: This isnt necessarily what your pipelines should look like, yet they can serve as reference.
What is Continuous Integration Continuous Integration is a process or a development practice of automated build and automated test i.e. A developer is required to commit his code multiple times into a shared repository where each integration is verified by automated build and test.
If the build fails/success it is notified to a developer and then he can take relevant actions.
What is Continuous Delivery Continuous Delivery is the practise where we keep our code deployable at any point which has passed all the test and has all the required configuration to push the code to production but hasn’t been deployed yet.
What is Continuous Deployment With the help of CI we have created s build for our application and is ready to push to production. In this step our build is ready and with CD we can deploy our application directly to QA environment and if everything goes well we can deploy the same build to production.
So basically, Continuous deployment is one step further than continuous delivery. With this practice, every change which passes all stages of your production pipeline is released to your customers.
Configuration Management: CM is all about maintaining the configuration of server which will be compatible to application requirement.
CI: A software development practice where members of a team integrate their work at least daily. Each integration is verified by automated build (include tests)to detect error as quick as possible. CD: CD Builds on CI, where you build software in such a way that the software can be released to production at any time.
In today’s fast-paced world of software development, companies are constantly seeking ways to accelerate their release cycles and deploy new features and fixes to users quickly. This has led to the rise of several related but distinct software development practices – continuous integration, continuous delivery, and continuous deployment. Though the names sound similar, there are some important differences between these three methodologies. In this article, we’ll break down the key distinctions and show when each approach is most applicable.
What is Continuous Integration?
Continuous integration (CI) is a development practice where developers frequently merge code changes into a shared repository, often multiple times per day. Each merge triggers an automated build and test process to catch integration bugs as early as possible
CI helps development teams avoid “integration hell”, where code works on individual developer machines but breaks when combined into the shared codebase By integrating regularly and automatically verifying each change, teams spot issues quickly and can fix them before they snowball.
The core aspects of continuous integration include:
- Using a version control system like Git for source code
- Having a shared code repository that all developers can access
- Automatically building the code into a runnable deliverable on each code commit
- Running automated tests to verify the code works as expected
- Providing rapid feedback to developers if bugs are found
CI is considered a best practice for modern software teams. When implemented well it leads to more stable code, faster debugging, and continuous progress on new work.
What is Continuous Delivery?
Continuous delivery (CD) builds on continuous integration by automating the release process. In addition to integrating and testing code, CD sets up automated processes to package and deploy the software to test environments on demand.
The goal is to keep the codebase deployable to users at any point. New code is integrated regularly via CI, then verified to be releasable via automated infrastructure and tests. Teams can then push releases out with minimal effort when needed.
Key aspects of continuous delivery include:
- Having mature CI processes in place
- Automating build, test, and deployment steps
- Ensuring deployments can happen at any time by automating release processes
- Releasing and testing code in production-like environments
- Having fast, reliable rollback procedures in case issues emerge
CD enables developers to ship incremental improvements to users more rapidly while minimizing risk. It works well for web services, mobile apps, and SaaS products that can be deployed independently of other systems.
What is Continuous Deployment?
Continuous deployment (CD) is an extension of continuous delivery where releases are fully automated. Instead of a manual approval or button click, validated code changes from CI are automatically pushed to production.
With proper test coverage, releases can happen numerous times per day. New code gets built, tested, and deployed automatically without human intervention. This allows end users to benefit from continuous incremental improvements.
Key points about continuous deployment include:
- It relies on mature continuous delivery practices being in place
- Deployments are fully automated once code is verified and approved
- Releases happen much more frequently – sometimes multiple times per day
- Developers focus on writing code rather than deployment processes
- Rollbacks and recovery processes are critical to deal with errors quickly
Continuous deployment works best for internet-scale companies like Facebook and Netflix. It lets them accelerate innovation for their users. But the approach requires extensive test automation and loosely coupled architectures to succeed.
Key Differences Summarized
While the terms sound alike, continuous integration, delivery, and deployment are distinct processes that serve different purposes. Here’s a quick summary of the key differences:
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Continuous integration focuses on developer workflow – frequently integrating code to a shared mainline to avoid big bang integrations. Automated builds and tests are run on each merge to catch bugs early.
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Continuous delivery expands on CI by automating release processes. Code is regularly built, tested, and deployed to production-like environments. Releases can be pushed to users quickly since everything is deployable.
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Continuous deployment fully automates the release process. Validated code changes are automatically pushed to production via the CI/CD pipeline. Human approvals are removed and users get continuous incremental updates.
When to Use Each Approach
The methodology you choose depends on your development team’s size, priorities, and risk tolerance:
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Nearly all teams should adopt continuous integration practices. Regular automated integration and testing improves code quality and developer productivity.
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Continuous delivery is ideal for teams that want to accelerate releases while minimizing risk. Checking each change against production-level environments provides confidence.
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Continuous deployment works best for high-performing engineering teams at internet scale companies. The focus is pure speed – deploying every validated change as fast as possible.
Evaluate your use case to pick the right approach. CI provides the foundation for CD and continuous deployment. You can then extend your capabilities over time as practices mature.
Implementing CI/CD/CD
Let’s discuss some best practices for implementing continuous integration, delivery, and deployment:
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Start with CI first. Focus on developer workflows before trying to automate full release processes. Get code merging and automated testing working smoothly.
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Encapsulate environments. Use containerization with Docker and orchestration tools like Kubernetes to replicate production environments for testing.
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Expand test automation. Invest in unit, integration, and UI testing to cover critical code paths and catch regressions.
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Monitor deployments. Use logging, monitoring, and alerting to gain visibility into releases. Be ready to quickly rollback any bad changes.
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Take an incremental approach. Don’t try to automate everything at once. Start small, deliver value continuously, and let working software guide efforts.
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Enable fast feedback. Provide channels for users and stakeholders to report issues early and often. Incorporate their feedback into the development process.
Key Benefits of CI/CD/CD
Implementing these practices provides many benefits for engineering teams and business stakeholders:
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Faster innovation – New features and fixes ship faster with automated pipelines
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Reduced risk – Code is thoroughly validated before reaching users, minimizing defects
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Reliability – Automation ensures releases follow consistent, repeatable processes
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Improved productivity – Less time spent on manual build and deploy tasks
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Developer happiness – Engineers focus on coding rather than release overhead
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Better quality – Tight feedback loops help identify bugs quickly
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Higher user satisfaction – Users enjoy more frequent updates and fixes
While adopting CI/CD/CD requires some upfront investment, the long-term productivity and business gains are immense.
Continuous integration, delivery, and deployment all aim to produce software that delights users as rapidly, safely, and sustainably as possible. CI establishes the foundation of merging code frequently and verifying changes automatically. CD builds on that by ensuring releases are automated and can happen anytime. And continuous deployment connects validated code changes directly to users without Slowing down.
Evaluate where your development practices stand today and pick the right starting point. Over time, you can continuously improve processes to achieve faster innovation, reduced risk, and quality at speed. The outcome will be software that customers actively want to use rather than software they are forced to tolerate.
12 Answers 12 Sorted by:
I Agree with your universitys definition. Continuous Integration is a strategy for how a developer can integrate code to the mainline continuously – as opposed to frequently.
You might claim that its merely a branching strategy in your version control system.
It has to do with the size of the tasks you assign to a developer; If a task is estimated to take 4-5 man-days then the developer will have no incitement to deliver anything for the next 4-5 days, because hes not done with anything – yet.
So size matters:
The ideal task size is not bigger than a days work. This way a developer will naturally have at least one integration per day.
There are basically three schools within Continuous Delivery:
Continuous Delivery is a natural extension of Continuous Integration
This school, looks at the Addison-Wesley “Martin Fowler” signature series and makes the assumption that since the 2007 release was called “Continuous Integration” and the one that followed in 2011 was called “Continuous Delivery” they are probably volume 1+2 of the same conceptual idea that has to do with continuous something.
Continuous Delivery has to do with Agile Software Development
This school takes off-set in the idea that Continuous Delivery is all about being able to support the principles in the agile movement, not just as a conceptual idea or a letter of intent but for real – in real life.
Taking offset in the first principle in the Agile Manifesto where the term “continuous delivery” is actually used for the first time:
This school claims that “Continuous Delivery” is a paradigm that embraces everything required to implement an automated verification of your “definition of done”.
This school accepts that “Continuous Delivery” and the buzz word or megatrend “DevOps” are flip sides of the same coin, in the sense that they both try to embrace or encapsulate this new paradigm or approach and not just a technique.
Continuous Delivery is a synonym to Continuous Deployment
The third school advocates that Continuous Deployment and Continuous Delivery can be used interchangeably to mean the same thing.
When something is ready in the hands of the developers, its immediately delivered to the end-users, which in most cases will mean that it should be deployed to the production environment. Hence “Deploy” and “Deliver” means the same.
Continuous Integration vs. Continuous Delivery vs Continuous Deployment: What Are The Differences?
What is the difference between continuous delivery & deployment?
Continuous Delivery (CD): With CD, an automated release process happens after integrations, builds, and tests. Continuous Deployment (CD): Every code change that goes through the production pipeline starts a deployment without the need for human intervention. Continuous integration, delivery, and deployment overlap in several ways.
What is the difference between continuous integration and continuous deployment?
The difference between continuous integration, continuous delivery, and continuous deployment is in how far each process goes to integrate, test, and deploy code through the DevOps cycle. Whatever your automation readiness, Puppet is there with the right infrastructure and IT automation solution at any scale.
What is the difference between continuous integration and delivery?
Continuous Integration happens before you build as you are testing code. Delivery means you can release something to the staging environment or the pre-production environment. Continuous Delivery is when your code is always ready to be released but isn’t pushed to production unless you make the decision to do so. It is a manual step.
What is continuous deployment & how does it work?
Continuous deployment automatically deploys every release through your pipeline (including testing) and to production. While they are different, continuous deployment is an extension of the continuous delivery concept. That is to say, releases that are moved forward using continuous delivery can eventually be deployed using continuous deployment.
