Added programmatic config.xml submission/retrieval support.

changelog.html

@@ -57,6 +57,8 @@ Upcoming changes</a>
 <ul class=image>
   <li class=bug>
     Fixed NPE in Groovy script execution via CLI (<a href="https://issues.jenkins-ci.org/browse/JENKINS-12302">issue 12302</a>)
+  <li class=rfe>
+    Supported programmatic retrieval/update of slave <tt>config.xml</tt>
   <li class=rfe>
     Breadcrumb now supports drop-down menu for faster navigation
     (<a href="https://groups.google.com/forum/#!topic/jenkinsci-dev/j9uCKnQB-Xw/discussion">discussion</a>)

core/src/main/java/hudson/model/Computer.java

@@ -64,6 +64,7 @@ import org.kohsuke.stapler.QueryParameter;
 import org.kohsuke.stapler.HttpResponses;
 import org.kohsuke.stapler.HttpResponse;
 import org.kohsuke.stapler.HttpRedirect;
+import org.kohsuke.stapler.WebMethod;
 import org.kohsuke.stapler.export.Exported;
 import org.kohsuke.stapler.export.ExportedBean;
 import org.kohsuke.args4j.Option;
@@ -87,6 +88,8 @@ import java.net.InetAddress;
 import java.net.NetworkInterface;
 import java.net.Inet4Address;
 
+import static javax.servlet.http.HttpServletResponse.*;
+
 /**
  * Represents the running state of a remote computer that holds {@link Executor}s.
  *
@@ -1069,27 +1072,57 @@ public /*transient*/ abstract class Computer extends Actionable implements Acces
         String name = Util.fixEmptyAndTrim(req.getSubmittedForm().getString("name"));
         Jenkins.checkGoodName(name);
         
-        final Jenkins app = Jenkins.getInstance();
-
         Node result = getNode().reconfigure(req, req.getSubmittedForm());
+        replaceBy(result);
+
+        // take the user back to the slave top page.
+        rsp.sendRedirect2("../"+result.getNodeName()+'/');
+    }
+
+    /**
+     * Accepts <tt>config.xml</tt> submission, as well as serve it.
+     */
+    @WebMethod(name = "config.xml")
+    public void doConfigDotXml(StaplerRequest req, StaplerResponse rsp)
+            throws IOException, ServletException {
+        checkPermission(Jenkins.ADMINISTER);
+        if (req.getMethod().equals("GET")) {
+            // read
+            rsp.setContentType("application/xml");
+            Jenkins.XSTREAM2.toXML(getNode(), rsp.getOutputStream());
+            return;
+        }
+        if (req.getMethod().equals("POST")) {
+            // submission
+            Node result = (Node)Jenkins.XSTREAM2.fromXML(req.getReader());
+
+            replaceBy(result);
+            return;
+        }
+
+        // huh?
+        rsp.sendError(SC_BAD_REQUEST);
+    }
+
+    /**
+     * Replaces the current {@link Node} by another one.
+     */
+    private void replaceBy(Node newNode) throws ServletException, IOException {
+        final Jenkins app = Jenkins.getInstance();
 
         // replace the old Node object by the new one
         synchronized (app) {
             List<Node> nodes = new ArrayList<Node>(app.getNodes());
             int i = nodes.indexOf(getNode());
             if(i<0) {
-                sendError("This slave appears to be removed while you were editing the configuration",req,rsp);
-                return;
+                throw new IOException("This slave appears to be removed while you were editing the configuration");
             }
 
-            nodes.set(i,result);
+            nodes.set(i, newNode);
             app.setNodes(nodes);
         }
-
-        // take the user back to the slave top page.
-        rsp.sendRedirect2("../"+result.getNodeName()+'/');
     }
-    
+
     /**
      * Really deletes the slave.
      */

core/src/main/resources/hudson/model/Computer/_api.jelly

@@ -28,4 +28,12 @@ THE SOFTWARE.
   <p>
     Load statistics of this computer has <a href="../loadStatistics/api/">its own separate API</a>.
   </p>
+
+  <h2>Fetch/Update config.xml</h2>
+  <p>
+    To programmatically obtain <tt>config.xml</tt>, hit <a href="../config.xml">this URL</a>.
+    You can also POST an updated <tt>config.xml</tt> to the same URL to programmatically
+    update the configuration of a node.
+  </p>
+
 </j:jelly>