jenkins学习之Jenkins流水线

Jenkins pipeline

最近由于项目需要，接触到了Jenkins 2.0版本，其中最重要的特性就是提供了对pipeline的支持。
简单的来说，就是把Jenkins1.0版本中，Project中的相关配置信息，如SVN/Git的配置，Parameter的配置等都变成Code，即Pipeline as Code。
这样的优势为可以通过写代码的形式配置Project，且Jenkins中内置了常用的steps。实现了构建步骤代码化、构建过程视图化。

声明性管道与脚本管道

声明式管道 和 脚本化管道 的主要区别在于它们的语法和灵活性

声明性管道是一个相对较新的特性，它提出了pipeline as code的概念,它使管道代码更易于读写。管道代码是在 Jenkinsfile 文件中编写的，可以将其存放到源代码管理系统（如Git）。 

脚本化管道是一个传统方式。在这个管道中，Jenkinsfile 被写在 Jenkins UI实例上。

虽然这两条管道都是基于Groovy DSL的，但是脚本化的流水线使用更严格的基于Groovy的语法，因为它是Groovy基金会上构建的第一条管道。由于这个Groovy脚本并不是所有用户都想要的，所以引入声明性管道是为了提供一种更简单、更具选择性的Groovy语法。


声明性管道在标记为“pipeline”的块中定义，而脚本化管道在“node”中定义。 

选择Declarative Pipeline还是Scripted Pipeline

最开始的Pipeline plugin，支持的只有一种脚本类型，就是Scripted Pipeline；
Declarative Pipeline为Pipeline plugin在2.5版本之后新增的一种脚本类型，
与原先的Scripted Pipeline一样，都可以用来编写脚本。

使用哪一种脚本格式呢，我又纠结了，也查询了些资料。
https://stackoverflow.com/questions/43484979/jenkins-scripted-pipeline-or-declarative-pipeline
http://jenkins-ci.361315.n4.nabble.com/Declarative-pipelines-vs-scripted-td4891792.html
https://e.printstacktrace.blog/jenkins-scripted-pipeline-vs-declarative-pipeline-the-4-practical-differences/
https://medium.com/getamis/%E7%B2%BE%E9%80%9A-jenkins-pipeline-part1-e8ef48d3543e
https://medium.com/@c9s/%E7%B2%BE%E9%80%9A-jenkins-pipeline-part2-transform-node-step-%E4%BB%A5%E5%8F%8A-declarative-pipeline-4942ddf67dd5
https://medium.com/@c9s/%E7%B2%BE%E9%80%9A-jenkins-pipeline-part3-declarative-pipeline-and-its-implementation-20ee724a4a2a

最后，我还是选择了Declarative Pipeline，这也是后续Open Blue Ocean所支持的类型。
相对而言，Declarative Pipeline比较简单，如果Groovy很熟的，用Scripted Pipeline可能更顺手。
另外，Declarative Pipeline中，是可以内嵌Scripted Pipeline代码的。

Declarative Pipeline fundamentals 声明性管道与脚本管道

In Declarative Pipeline syntax, the pipeline block defines all the work done throughout your entire Pipeline.

Jenkinsfile (Declarative Pipeline)

pipeline {
    agent any  // Execute this Pipeline or any of its stages, on any available agent.
    stages {
        stage('Build') { //Defines the "Build" stage.
            steps {
                // Perform some steps related to the "Build" stage.
            }
        }
        stage('Test') { //Defines the "Test" stage.
            steps {
                // Perform some steps related to the "Test" stage.
            }
        }
        stage('Deploy') { //Defines the "Deploy" stage.
            steps {
                // Perform some steps related to the "Deploy" stage.
            }
        }
    }
}

Scripted Pipeline fundamentals 声明性管道与脚本管道

In Scripted Pipeline syntax, one or more node blocks do the core work throughout the entire Pipeline. Although this is not a mandatory requirement of Scripted Pipeline syntax, confining your Pipeline’s work inside of a node block does two things:

    Schedules the steps contained within the block to run by adding an item to the Jenkins queue. As soon as an executor is free on a node, the steps will run.

    Creates a workspace (a directory specific to that particular Pipeline) where work can be done on files checked out from source control.

Caution: Depending on your Jenkins configuration, some workspaces may not get automatically cleaned up after a period of inactivity. See tickets and discussion linked from JENKINS-2111 for more information.





Jenkinsfile (Scripted Pipeline)

node {  //Execute this Pipeline or any of its stages, on any available agent. 
    stage('Build') { // Defines the "Build" stage. stage blocks are optional in Scripted Pipeline syntax. However, implementing stage blocks in a Scripted Pipeline provides clearer visualization of each `stage’s subset of tasks/steps in the Jenkins UI.
        // Perform some steps related to the "Build" stage.
    }
    stage('Test') { //Defines the "Test" stage.
        // Defines the "Test" stage
    }
    stage('Deploy') { //Defines the "Deploy" stage.
        // Defines the "Deploy" stage.
    }
}

来源：oschina

链接：https://my.oschina.net/u/4276902/blog/4479889