Continuous deployment contrasts withcontinuous delivery (also abbreviated CD), a similar approach in which software functionalities are also frequently delivered and deemed to be potentially capable of being deployed, but are actually not deployed.[4] As such, continuous deployment can be viewed as a more complete form of automation than continuous delivery.[5]
Diagram highlighting the difference in deployment processes betweencontinuous delivery and continuous deployment
Continuous deployment extends the principles ofcontinuous integration and delivery by including fully automated production deployment without the need for manual approval, instead relying on rigorous automated testing.[7] Reviews may still take place in the form developer-developercode reviews, but the need for intermediary reviewers such as achange-advisory board is minimized.[8]
Because code changes are deployed automatically, continuous deployment requires a much higher standard of automated testing, as test quality determines the reliability of releases.[9] Without this, the risk of introducing production failures outweighs the benefits of deployment automation.
In addition, continuous deployment emphasizes small incremental changes and dark launches through the use offeature toggles. Developers can deploy code into production months before a public release by gradually adding functionality in small chunks, verifying stability, and then enabling the feature for users when it is considered ready.[10][9]
Continuous deployment removes the need to wait for releases, as once a change passes internal testing it is automatically deployed to production.[11] This allows for shortertime-to-market and more frequent releases,[8] which in turn increases customer satisfaction and provides companies with more marketing opportunities.[12]
A major motivation for continuous deployment is that deploying software into the field more often makes it easier to find, catch, and fix bugs.[13] Deploying small, incremental changes makes it easier to trace the origin of bugs, since issues will be isolated to a recent and relatively small code change.[14][12]
Under this methodology, new software features can be released to customers more quickly and frequently after their development, accelerating the delivery of value to customers and enhancing customer satisfaction. Teams can begin to collect customer feedback almost immediately, driving rapid innovation of relevant features.[12][8]
Continuous delivery requires a significant investment in adequate test coverage, real-time monitoring, and strong continuous integration pipelines to prevent bugs from reaching production.[15][16][11][12] Customers may also find software that is constantly changing creates a learning curve which can negatively affect their experience.[12]
Moving to continuous delivery is also a culture shift for developers who are accustomed to traditional release cycles, often requiring a provenDevOps process.[17] Adopting this process requires collaboration among multiple stakeholders, including development teams, leadership, operations, and quality assurance. A 2007 study recorded one company manager's reaction to continuous delivery: "When the release team and I confronted the developers with our new process - releasing a story as soon as it is signed off - it scared the hell out of them."[18]
In an environment in which data-centricmicroservices provide the functionality, and where the microservices can have multiple instances, continuous deployment consists of instantiating the new version of a microservice and retiring the old version once it has drained all the requests in flight.[19][20][21]
^Holmstrom Olsson, Helena; Alahyari, Hiva; Bosch, Jan (2012). "Climbing the "Stairway to Heaven" -- A Mulitiple-Case Study Exploring Barriers in the Transition from Agile Development towards Continuous Deployment of Software".2012 38th Euromicro Conference on Software Engineering and Advanced Applications.IEEE Computer Society. pp. 392–399.doi:10.1109/SEAA.2012.54.ISBN978-0-7695-4790-9.S2CID15199568.
^Claps, Gerry Gerard; Berntsson Svenssonb, Richard; Aurum, Aybüke (2014). "On the journey to continuous deployment: Technical and social challenges along the way".Information and Software Technology.57:21–31.doi:10.1016/j.infsof.2014.07.009.
^"Continuous Deployment: An Essential Guide".IBM. 2019-10-02. Retrieved2022-11-28.Continuous deployment is the natural outcome of continuous delivery done well. Eventually, the manual approval delivers little or no value and is merely slowly things down. At that point, it is done away with and continuous delivery becomes continuous deployment.
^Claps, Gerry Gerard; Berntsson Svenssonb, Richard; Aurum, Aybüke (2014). "On the journey to continuous deployment: Technical and social challenges along the way".Information and Software Technology.57:21–31.doi:10.1016/j.infsof.2014.07.009.
^"What is CD?".Amazon Web Services, Inc. Retrieved2025-10-03.
^Olsson, Helena Holmström; Alahyari, Hiva; Bosch, Jan (September 2012). "Climbing the "Stairway to Heaven" -- A Mulitiple-Case Study Exploring Barriers in the Transition from Agile Development towards Continuous Deployment of Software".2012 38th Euromicro Conference on Software Engineering and Advanced Applications. pp. 392–399.doi:10.1109/SEAA.2012.54.ISBN978-0-7695-4790-9.
