[JENKINS-20609] refactored script hook

in preparation of introducing other hooks

core/src/main/java/hudson/init/impl/GroovyInitScript.java

@@ -23,20 +23,13 @@
  */
 package hudson.init.impl;
 
-import groovy.lang.GroovyCodeSource;
-import groovy.lang.GroovyShell;
+import hudson.init.Initializer;
+import jenkins.model.Jenkins;
+import jenkins.util.groovy.GroovyHookScript;
 
-import java.io.File;
-import java.io.FileFilter;
 import java.io.IOException;
-import java.net.URL;
-import java.util.Arrays;
-import java.util.logging.Logger;
 
-import jenkins.model.Jenkins;
-import static hudson.init.InitMilestone.JOB_LOADED;
-import hudson.init.Initializer;
-import java.util.logging.Level;
+import static hudson.init.InitMilestone.*;
 
 /**
  * Run the initialization script, if it exists.
@@ -46,46 +39,6 @@ import java.util.logging.Level;
 public class GroovyInitScript {
     @Initializer(after=JOB_LOADED)
     public static void init(Jenkins j) throws IOException {
-        URL bundledInitScript = j.servletContext.getResource("/WEB-INF/init.groovy");
-        if (bundledInitScript!=null) {
-            LOGGER.info("Executing bundled init script: "+bundledInitScript);
-            execute(new GroovyCodeSource(bundledInitScript));
-        }
-
-        File initScript = new File(j.getRootDir(),"init.groovy");
-        if(initScript.exists()) {
-            execute(initScript);
-        }
-        
-        File initScriptD = new File(j.getRootDir(),"init.groovy.d");
-        if (initScriptD.isDirectory()) {
-            File[] scripts = initScriptD.listFiles(new FileFilter() {
-                public boolean accept(File f) {
-                    return f.getName().endsWith(".groovy");
-                }
-            });
-            if (scripts!=null) {
-                // sort to run them in a deterministic order
-                Arrays.sort(scripts);
-                for (File f : scripts)
-                    execute(f);
-            }
-        }
+        new GroovyHookScript("init").run();
     }
-
-    private static void execute(File initScript) throws IOException {
-        LOGGER.info("Executing "+initScript);
-        execute(new GroovyCodeSource(initScript));
-    }
-
-    private static void execute(GroovyCodeSource initScript) {
-        GroovyShell shell = new GroovyShell(Jenkins.getInstance().getPluginManager().uberClassLoader);
-        try {
-            shell.evaluate(initScript);
-        } catch (RuntimeException x) {
-            LOGGER.log(Level.WARNING, "Failed to run script " + initScript.getName(), x);
-        }
-    }
-
-    private static final Logger LOGGER = Logger.getLogger(GroovyInitScript.class.getName());
 }

core/src/main/java/jenkins/util/groovy/GroovyHookScript.java

+package jenkins.util.groovy;
+
+import groovy.lang.GroovyCodeSource;
+import groovy.lang.GroovyShell;
+import jenkins.model.Jenkins;
+
+import java.io.File;
+import java.io.FileFilter;
+import java.io.IOException;
+import java.net.URL;
+import java.util.Arrays;
+import java.util.Set;
+import java.util.TreeSet;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/**
+ * A collection of Groovy scripts that are executed as various hooks.
+ *
+ * <p>
+ * For a given hook name, like "init", the following locations are searched for hook scripts,
+ * and then they are executed in turn.
+ *
+ * <ol>
+ * <li>/WEB-INF/<i>HOOK</i>.groovy in the war file
+ * <li>/WEB-INF/<i>HOOK</i>.groovy.d/*.groovy in the war file
+ * <li>$JENKINS_HOME/<i>HOOK</i>.groovy
+ * <il>$JENKINS_HOME/<i>HOOK</i>.groovy.d/*.groovy
+ * </ol>
+ *
+ * <p>
+ * Scripts inside <tt>/WEB-INF</tt> is meant for OEM distributions of Jenkins. Files inside
+ * <tt>$JENKINS_HOME</tt> are for installation local settings. Use of <tt>HOOK.groovy.d</tt>
+ * allows configuration management tools to control scripts easily.
+ *
+ * @author Kohsuke Kawaguchi
+ */
+public class GroovyHookScript {
+    private final String hook;
+
+    public GroovyHookScript(String hook) {
+        this.hook = hook;
+    }
+
+    public void run() throws IOException {
+        Jenkins j = Jenkins.getInstance();
+        final String hookGroovy = hook+".groovy";
+        final String hookGroovyD = hook+".groovy.d";
+
+        URL bundled = j.servletContext.getResource("/WEB-INF/"+ hookGroovy);
+        execute(bundled);
+
+        Set<String> resources = j.servletContext.getResourcePaths("/WEB-INF/"+ hookGroovyD +"/");
+        if (resources!=null) {
+            // sort to execute them in a deterministic order
+            for (String res : new TreeSet<String>(resources)) {
+                bundled = j.servletContext.getResource(res);
+                execute(bundled);
+            }
+        }
+
+        File script = new File(j.getRootDir(), hookGroovy);
+        execute(script);
+
+        File scriptD = new File(j.getRootDir(), hookGroovyD);
+        if (scriptD.isDirectory()) {
+            File[] scripts = scriptD.listFiles(new FileFilter() {
+                public boolean accept(File f) {
+                    return f.getName().endsWith(".groovy");
+                }
+            });
+            if (scripts!=null) {
+                // sort to run them in a deterministic order
+                Arrays.sort(scripts);
+                for (File f : scripts)
+                    execute(f);
+            }
+        }
+    }
+
+    protected void execute(URL bundled) throws IOException {
+        if (bundled!=null) {
+            LOGGER.info("Executing bundled script: "+bundled);
+            execute(new GroovyCodeSource(bundled));
+        }
+    }
+
+    protected void execute(File f) throws IOException {
+        if (f.exists()) {
+            LOGGER.info("Executing "+f);
+            execute(new GroovyCodeSource(f));
+        }
+    }
+
+    protected void execute(GroovyCodeSource s) {
+        try {
+            createShell().evaluate(s);
+        } catch (RuntimeException x) {
+            LOGGER.log(Level.WARNING, "Failed to run script " + s.getName(), x);
+        }
+    }
+
+    /**
+     * Can be used to customize the environment in which the script runs.
+     */
+    protected GroovyShell createShell() {
+        return new GroovyShell(Jenkins.getInstance().getPluginManager().uberClassLoader);
+    }
+
+    private static final Logger LOGGER = Logger.getLogger(GroovyHookScript.class.getName());
+}