Fix: Don't destroy credentials when re-creating folders

As noted in JENKINS-44681, any credentials on folders are lost when
re-creating folders, as we don't merge the existing credentials with the
newly created folder.

To do this, we need to find any instances of
`FolderCredentialsProvider.FolderCredentialsProperty` in the `Folder`'s
and if present, merge the credentials.

We need to promote our dependency on `cloudbees-folder` to a runtime
dependency, as we now need to reference the `Folder` and any
`FolderCredentialsProperty`s.

Note that in `JenkinsJobManagementSpec`, we need to use
`getNodeTemplate` to ensure that the real implementation of `getXml` is
called, which will execute the `configuredBlocks`.

Because we need to call to the `configure` method, we need to call out
to a new Groovy file, `DslItemConfigurer`, which processes the new
`AbstractFolderProperty` and converts it to the correct XML
representation. When parsing it, we need to make sure we add a valid XML
header, otherwise `XmlParser` will reject it.

Closes JENKINS-44681.

job-dsl-plugin/build.gradle

@@ -89,6 +89,7 @@ dependencies {
     compile(project(':job-dsl-core'))  {
         exclude group: 'org.jvnet.hudson', module:'xstream'
     }
+    jenkinsPlugins 'org.jenkins-ci.plugins:cloudbees-folder:5.14'
     jenkinsPlugins 'org.jenkins-ci.plugins:structs:1.19'
     jenkinsPlugins 'org.jenkins-ci.plugins:script-security:1.54'
     optionalJenkinsPlugins('org.jenkins-ci.plugins:vsphere-cloud:1.1.11') {
@@ -99,7 +100,6 @@ dependencies {
     optionalJenkinsPlugins 'io.jenkins:configuration-as-code:1.15'
     jenkinsTest 'io.jenkins:configuration-as-code:1.15'
     jenkinsTest 'io.jenkins:configuration-as-code:1.15:tests'
-    jenkinsTest 'org.jenkins-ci.plugins:cloudbees-folder:5.14'
     jenkinsTest 'org.jenkins-ci.plugins:matrix-auth:1.3'
     jenkinsTest 'org.jenkins-ci.plugins:nested-view:1.14'
     jenkinsTest 'org.jenkins-ci.plugins:credentials:2.1.10'

job-dsl-plugin/src/main/groovy/javaposse/jobdsl/plugin/DslItemConfigurer.groovy

@@ -0,0 +1,21 @@
+package javaposse.jobdsl.plugin
+
+import com.cloudbees.hudson.plugins.folder.AbstractFolderProperty
+import hudson.model.Items
+import javaposse.jobdsl.dsl.Item
+
+class DslItemConfigurer {
+    private static final String XML_HEADER = "<?xml version='1.1' encoding='UTF-8'?>"
+
+    /**
+     * Merge an {@link AbstractFolderProperty} into a new {@link Item}'s properties.
+     *
+     * @param item the property to merge
+     * @param dslItem the DSL item to merge the properties into
+     */
+    static void mergeCredentials(AbstractFolderProperty<?> property, Item dslItem) {
+        String xml = Items.XSTREAM2.toXML(property)
+        Node node = new XmlParser().parseText(XML_HEADER + xml)
+        dslItem.configure { p -> p / 'properties' << node }
+    }
+}

job-dsl-plugin/src/main/groovy/javaposse/jobdsl/plugin/JenkinsJobManagement.java

@@ -1,5 +1,13 @@
 package javaposse.jobdsl.plugin;
 
+import static hudson.model.Result.UNSTABLE;
+import static hudson.model.View.createViewFromXML;
+import static java.lang.String.format;
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import com.cloudbees.hudson.plugins.folder.AbstractFolderProperty;
+import com.cloudbees.hudson.plugins.folder.Folder;
+import com.cloudbees.hudson.plugins.folder.properties.FolderCredentialsProvider.FolderCredentialsProperty;
 import com.google.common.collect.Collections2;
 import com.google.common.collect.Iterables;
 import com.thoughtworks.xstream.io.xml.XppDriver;
@@ -52,6 +60,7 @@
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 import java.util.logging.Level;
 import java.util.logging.Logger;
@@ -444,6 +453,7 @@ private String lookupJob(String path) throws IOException {
     }
 
     private boolean updateExistingItem(AbstractItem item, javaposse.jobdsl.dsl.Item dslItem) {
+        mergeCredentials(item, dslItem);
         String config = dslItem.getXml();
 
         item.checkPermission(Item.EXTENDED_READ);
@@ -576,6 +586,22 @@ private void renameJob(Job from, String to) throws IOException {
         from.renameTo(FilenameUtils.getName(to));
     }
 
+    private void mergeCredentials(AbstractItem item, javaposse.jobdsl.dsl.Item dslItem) {
+        if (item instanceof Folder) {
+            Folder folder = (Folder) item;
+            Optional<AbstractFolderProperty<?>> maybeProperty =
+                folder.getProperties().stream()
+                .filter(p -> p instanceof FolderCredentialsProperty)
+                .findFirst();
+
+            if (maybeProperty.isPresent()) {
+                LOGGER.log(Level.FINE, format("Merging credentials for %s", item.getName()));
+                DslItemConfigurer.mergeCredentials(maybeProperty.get(), dslItem);
+            }
+        }
+    }
+
+
     @SuppressWarnings("unchecked")
     private static <I extends AbstractItem & TopLevelItem> void move(Item item, DirectlyModifiableTopLevelItemGroup destination) throws IOException {
         Items.move((I) item, destination);

job-dsl-plugin/src/test/groovy/javaposse/jobdsl/plugin/JenkinsJobManagementSpec.groovy

@@ -1,7 +1,16 @@
 package javaposse.jobdsl.plugin
 
+import com.cloudbees.hudson.plugins.folder.AbstractFolder
+import com.cloudbees.hudson.plugins.folder.AbstractFolderProperty
+import com.cloudbees.hudson.plugins.folder.AbstractFolderPropertyDescriptor
 import com.cloudbees.hudson.plugins.folder.Folder
+import com.cloudbees.hudson.plugins.folder.properties.FolderCredentialsProvider
+import com.cloudbees.plugins.credentials.CredentialsScope
+import com.cloudbees.plugins.credentials.domains.Domain
+import com.cloudbees.plugins.credentials.domains.DomainCredentials
+import com.cloudbees.plugins.credentials.impl.UsernamePasswordCredentialsImpl
 import com.google.common.io.Resources
+import hudson.Extension
 import hudson.FilePath
 import hudson.model.AbstractBuild
 import hudson.model.AllView
@@ -632,6 +641,32 @@ class JenkinsJobManagementSpec extends Specification {
         e.message == 'Type of item "my-job" does not match existing type, item type can not be changed'
     }
 
+    def 'createOrUpdateConfig should preserve credentials if they exist on a folder'() {
+        setup:
+        Folder folder = jenkinsRule.createProject(Folder, 'folder')
+        folder.addProperty(createCredentialProperty())
+
+        when:
+        jobManagement.createOrUpdateConfig(createItem('folder', '/folder.xml'), false)
+
+        then:
+        def actual = jenkinsRule.jenkins.getItem('folder')
+        actual.properties.size() == 1
+    }
+
+    def 'createOrUpdateConfig should ignore other properties on the folder'() {
+        setup:
+        Folder folder = jenkinsRule.createProject(Folder, 'folder')
+        folder.addProperty(new FakeProperty())
+
+        when:
+        jobManagement.createOrUpdateConfig(createItem('folder', '/folder.xml'), false)
+
+        then:
+        def actual = jenkinsRule.jenkins.getItem('folder')
+        actual.properties.size() == 0
+    }
+
     def 'createOrUpdateView should work if view type changes'() {
         setup:
         jenkinsRule.jenkins.addView(new AllView('foo'))
@@ -973,10 +1008,27 @@ class JenkinsJobManagementSpec extends Specification {
         Resources.toString(Resources.getResource(resourceName), UTF_8)
     }
 
+    private static FolderCredentialsProvider.FolderCredentialsProperty createCredentialProperty() {
+        UsernamePasswordCredentialsImpl  credentials = new UsernamePasswordCredentialsImpl(CredentialsScope.GLOBAL, '',
+            '', '', '')
+        DomainCredentials[] domainCredentials = new DomainCredentials[1]
+        domainCredentials[0] = new DomainCredentials(Domain.global(), Collections.singletonList(credentials))
+
+        new FolderCredentialsProvider.FolderCredentialsProperty(domainCredentials)
+    }
+
+    private static class FakeProperty extends AbstractFolderProperty<AbstractFolder<?>> {
+
+        @Extension(optional = true)
+            static class DescriptorImpl extends AbstractFolderPropertyDescriptor {
+                final String displayName = ''
+            }
+    }
+
     private Item createItem(String name, String config) {
         new Item(jobManagement, name) {
             @Override
-            Node getNode() {
+            Node getNodeTemplate() {
                 new XmlParser().parse(JenkinsJobManagementSpec.getResourceAsStream(config))
             }
         }

job-dsl-plugin/src/test/resources/folder.xml

@@ -0,0 +1,2 @@
+<com.cloudbees.hudson.plugins.folder.Folder>
+</com.cloudbees.hudson.plugins.folder.Folder>