Maven2 : SCM

通常在Nightly Build的環節，我比較喜歡Clean Build，也就是從Checkout、Compile、Test、Deploy都是一個動作完成的Compile、Test、Deploy都可以靠Maven或Ant完成，但是自VCS中checkout source code就要看plugin的支援程度了。即便是plugin支援度不夠，只要該種VCS有提供command line的模式，我想就能利用shell或script的方式來達到完整的Clean Build。 例如：

git clone [url] ＃checkout source code from VCS
cd [project]
mvn site -Pprod

當然利用Maven提供的SCM來處理也是不錯，除了checkin, checkout之外也可以利用scm plugin來列出changelog或add、remove檔案，不過我個人是比較少用到這些功能就是。

Maven提供的SCM Plugin請參考 http://maven.apache.org/scm/plugins/index.html， 而支援的SCM的完整度則可以考http://maven.apache.org/scm/matrix.html

為了使用Maven的SCM Plugin，通常單獨將<scm>建一個pom.xml，其他plugin或build的東西就免寫了，當然要用原來project的pom.xml也無不可，簡單看個例子。

<project xsi:schemalocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0">
  <modelversion>4.0.0</modelversion>

  <groupid>idv.elliot</groupid>
  <artifactid>BuildDemo</artifactid>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>pom</packaging>

  <name>BuildDemo</name>
  <url>http://github.com/ElliotChen/BuildDemo </url>

  <scm>
    <!-- 僅供讀取的Connection URL, 前面必需加上scm:xxx -->
    <connection>scm:git:git://github.com/ElliotChen/BuildDemo.git </connection>
    <!-- 可以執行checkin的Connection URL, 前面必需加上scm:xxx -->
    <developerconnection>scm:git:git://github.com/ElliotChen/BuildDemo.git </developerconnection>
    <url>http://github.com/ElliotChen/BuildDemo </url>
  </scm>
  <build>
    <plugins>
      <plugin>
        <groupid>org.apache.maven.plugins</groupid>
        <artifactid>maven-scm-plugin</artifactid>
        <version>1.3</version>
        <!-- Checkout之後要執行的Goal -->
        <configuration>
          <goals>site</goals>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project> 

簡單來說，只要在<scm>裡的<connection>填入SCM checkout source code的url，然後在url之前依你使用的SCM種類加上指定的prefix，然後在<maven-scm-plugin>的<configuration>中填上接下來要執行的goal，最後執行

mvn clean scm:bootstrap 

這樣就可以看到像下列的輸出:

[INFO] [scm:bootstrap {execution: default-cli}]
[INFO] Removing /Users/elliot/tmp/target/checkout
[INFO] Executing: /bin/sh -c cd /Users/elliot/tmp/target && git clone git://github.com/ElliotChen/BuildDemo.git /Users/elliot/tmp/target/checkout
[INFO] Working directory: /Users/elliot/tmp/target
[INFO] Executing: /bin/sh -c cd /Users/elliot/tmp/target/checkout && git pull git://github.com/ElliotChen/BuildDemo.git master
[INFO] Working directory: /Users/elliot/tmp/target/checkout
[INFO] Executing: /bin/sh -c cd /Users/elliot/tmp/target/checkout && git checkout
[INFO] Working directory: /Users/elliot/tmp/target/checkout
[INFO] Executing: /bin/sh -c cd /Users/elliot/tmp/target/checkout && git ls-files
[INFO] Working directory: /Users/elliot/tmp/target/checkout
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Building BuildDemo
[INFO]    task-segment: [site]
[INFO] ------------------------------------------------------------------------
[INFO] [site:site {execution: default-site}]