曾经在内部的培训课上去提出这个问题,去曾经就类似的问题和去同事讨论,也曾经在某“德无哦普斯”群里和相关专家沟通过。但是在准备DevOps Professional课件的过程中,再一次颠覆了原先的理解。

用了一晚上时间,仔去细翻看DevOps Handbook相关内容,在网上也查阅了大量资料,试图去解读这两个概念的含义,以及背后的原因。

Jez Humble说,“在过去的5年里,人们对持续交去付和持续部署的区别有所误解。“的确,我自己对两者的看法和定义也发生去了改变。每个组织都应去该根据自己的需求做出选择。我们不应该关注形式,而去应该关注结果:部署应该是无风险、按需进行的一键式操作。”

这次不去争辩持续交付的定义,关键是在这个概念背后,都有哪些实践,以及原因和产生的结果。比叫什么更重要的是为什么。

Continuous Delivery持续交付的各种说法“持续交付:发布可靠软件的系统方法”

持续交付是最早由Jez Humble和David Farley提出,并在“持续交付:发布可靠软件的系统方法”一书中对其实现进行系统说明。

全书并没有找到明确的持续交付定义,原书英文版书名是“Continuous Delivery: Reliable Software Releases through Build, Test, and Deployment Automation”。自然的,持续交付是将部署自动化包含在内的,而且也把Release和Delivery关联在一起。这里的自动化部署,更多的是部署流水线,不是持续部署的概念。

在Jez Humble的以下文章中,对他为什么会选择Continuous Delivery有详尽的描述 https://continuousdelivery.com/2010/08/continuous-delivery-vs-continuous-deployment/

事实上,continuous deployment的概念是Timothy Fitz,在Jez的Continuous Delivery出版的前一年2009年提出的。Jez认为:

“What makes continuous deployment special is deploying every change that passes the automated tests (and optionally a short QA gate) to production. Continuous deployment is the practice of releasing every good build to users - a more accurate name might have been "continuous release”.” 因此此处的持续部署是将所有通过自动化测试以及QA环境的构建,自动发布给客户的动作,Jez说更准确的名称应该是“持续发布”(又引入一个词汇,进一步混乱)。

“Continuous delivery is about putting the release schedule in the hands of the business, not in the hands of IT”

持续交付更像是一个业务行为,而不是技术行为。

“So when can you say you're doing continuous delivery? I'd say it's when you could flip a switch to go to continuous deployment if you decided that was the best way to deliver value to your customers.”

所以持续交付是在部署到生产环境之前,加了一个业务判断,决定是否交付给客户,然后一键部署到生产环境。这一定义与随后的大部分文档相似,包括DevOps Handbook。

Martin Fowler的持续交付

https://martinfowler.com/bliki/ContinuousDelivery.html

Martin 2013年的持续交付文章中,也对持续交付与持续部署进行了比较。观点与Jez的相似,同时也援引了Jez的文章。

持续部署是自动化的将一切变更放到生产环境,而持续交付则有判断决策过程,并直接说“ In order to do Continuous Deployment you must be doing Continuous Delivery.”

“Continuous Delivery is sometimes confused with Continuous Deployment.Continuous Deployment means that every change goes through the pipeline and automatically gets put into production, resulting in many production deployments every day. Continuous Delivery just means that you are able to do frequent deployments but may choose not to do it, usually due to businesses preferring a slower rate of deployment. In order to do Continuous Deployment you must be doing Continuous Delivery.”

对持续交付与持续部署的关系,Martin也承认两个概念容易造成困惑,持续部署代表将所有变更自动通过流水线推到生产环境,持续交付则意味着你有能力这样做,但可以基于业务选择不这样做。

所以我不觉得两者有谁包含谁,两者在这个层面讲,一个是技术领域,一个是业务领域。

乔梁的持续交付

而同时期乔梁的演讲资料中,持续交付的说明,被定义为交付业务价值,而不是IT内部团队之间的交付。