[JENKINS-49594] Implement extension points to contribute pod template…

src/main/java/org/csanchez/jenkins/plugins/kubernetes/KubernetesCloud.java

@@ -188,9 +188,7 @@ public List<PodTemplate> getTemplates() {
      */
     @Nonnull
     public List<PodTemplate> getAllTemplates() {
-        List<PodTemplate> podTemplates = new ArrayList<>(PodTemplateMap.get().getTemplates(this));
-        podTemplates.addAll(templates);
-        return Collections.unmodifiableList(podTemplates);
+        return PodTemplateSource.getAll(this);
     }
 
     @DataBoundSetter
@@ -397,9 +395,7 @@ public synchronized Collection<NodeProvisioner.PlannedNode> provision(@CheckForN
 
             List<NodeProvisioner.PlannedNode> r = new ArrayList<NodeProvisioner.PlannedNode>();
 
-            ArrayList<PodTemplate> templates = getMatchingTemplates(label);
-
-            for (PodTemplate t: templates) {
+            for (PodTemplate t: getTemplatesFor(label)) {
                 LOGGER.log(Level.INFO, "Template: " + t.getDisplayName());
                 for (int i = 1; i <= excessWorkload; i++) {
                     if (!addProvisionedSlave(t, label)) {
@@ -491,16 +487,20 @@ public PodTemplate getTemplate(@CheckForNull Label label) {
      * Gets all PodTemplates that have the matching {@link Label}.
      * @param label label to look for in templates
      * @return list of matching templates
+     * @deprecated Use {@link #getTemplatesFor(Label)} instead.
      */
+    @Deprecated
     public ArrayList<PodTemplate> getMatchingTemplates(@CheckForNull Label label) {
-        ArrayList<PodTemplate> podList = new ArrayList<PodTemplate>();
-        List<PodTemplate> podTemplates = getAllTemplates();
-        for (PodTemplate t : podTemplates) {
-            if ((label == null && t.getNodeUsageMode() == Node.Mode.NORMAL) || (label != null && label.matches(t.getLabelSet()))) {
-                podList.add(t);
-            }
-        }
-        return podList;
+        return new ArrayList<>(getTemplatesFor(label));
+    }
+
+    /**
+     * Gets all PodTemplates that have the matching {@link Label}.
+     * @param label label to look for in templates
+     * @return list of matching templates
+     */
+    public List<PodTemplate> getTemplatesFor(@CheckForNull Label label) {
+        return PodTemplateFilter.applyAll(this, getAllTemplates(), label);
     }
 
     /**
@@ -635,4 +635,12 @@ private Object readResolve() {
         return this;
     }
 
+    @Extension
+    public static class PodTemplateSourceImpl extends PodTemplateSource {
+        @Nonnull
+        @Override
+        public List<PodTemplate> getList(@Nonnull KubernetesCloud cloud) {
+            return cloud.getTemplates();
+        }
+    }
 }

src/main/java/org/csanchez/jenkins/plugins/kubernetes/PodTemplateFilter.java

@@ -0,0 +1,60 @@
+package org.csanchez.jenkins.plugins.kubernetes;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import javax.annotation.CheckForNull;
+import javax.annotation.Nonnull;
+
+import hudson.ExtensionList;
+import hudson.ExtensionPoint;
+import hudson.model.Label;
+
+/**
+ * Filters a pod template according to criteria.
+ */
+public abstract class PodTemplateFilter implements ExtensionPoint {
+    /**
+     * Returns a list of all implementations of {@link PodTemplateFilter}.
+     * @return a list of all implementations of {@link PodTemplateFilter}.
+     */
+    public static ExtensionList<PodTemplateFilter> all() {
+        return ExtensionList.lookup(PodTemplateFilter.class);
+    }
+
+    /**
+     * Pass the given pod templates list into all filters implementations.
+     *
+     * @param cloud The cloud instance the pod templates are getting considered for
+     * @param podTemplates The initial list of pod templates
+     * @param label The label that was requested for provisioning
+     * @return The pod template list after filtering
+     */
+    public static List<PodTemplate> applyAll(@Nonnull KubernetesCloud cloud, @Nonnull List<PodTemplate> podTemplates, @CheckForNull Label label) {
+        List<PodTemplate> result = new ArrayList<>();
+        for (PodTemplate t : podTemplates) {
+            PodTemplate output = null;
+            for (PodTemplateFilter f : all()) {
+                output = f.transform(cloud, t, label);
+                if (output == null) {
+                    break;
+                }
+            }
+            if (output != null) {
+                result.add(output);
+            }
+        }
+        return result;
+    }
+
+    /**
+     * Transforms a pod template definition.
+     *
+     * @param cloud The {@link KubernetesCloud} instance the {@link PodTemplate} instances will be scheduled into.
+     * @param podTemplate The input pod template to process.
+     * @param label The label that was requested for provisioning
+     * @return A new pod template after transformation. It can be null if the filter denies access to the given pod template.
+     */
+    @CheckForNull
+    protected abstract PodTemplate transform(@Nonnull KubernetesCloud cloud, @Nonnull PodTemplate podTemplate, @CheckForNull Label label);
+}

src/main/java/org/csanchez/jenkins/plugins/kubernetes/PodTemplateLabelFilter.java

@@ -0,0 +1,22 @@
+package org.csanchez.jenkins.plugins.kubernetes;
+
+import javax.annotation.CheckForNull;
+import javax.annotation.Nonnull;
+
+import hudson.Extension;
+import hudson.model.Label;
+import hudson.model.Node;
+
+/**
+ * Implementation of {@link PodTemplateFilter} filtering pod templates matching the right label.
+ */
+@Extension
+public class PodTemplateLabelFilter extends PodTemplateFilter {
+    @Override
+    protected PodTemplate transform(@Nonnull KubernetesCloud cloud, @Nonnull PodTemplate podTemplate, @CheckForNull Label label) {
+        if ((label == null && podTemplate.getNodeUsageMode() == Node.Mode.NORMAL) || (label != null && label.matches(podTemplate.getLabelSet()))) {
+            return podTemplate;
+        }
+        return null;
+    }
+}

src/main/java/org/csanchez/jenkins/plugins/kubernetes/PodTemplateSource.java

@@ -0,0 +1,32 @@
+package org.csanchez.jenkins.plugins.kubernetes;
+
+import static java.util.stream.Collectors.toList;
+
+import java.util.Collection;
+import java.util.List;
+
+import javax.annotation.Nonnull;
+
+import hudson.ExtensionList;
+import hudson.ExtensionPoint;
+
+/**
+ * A source of pod templates.
+ */
+public abstract class PodTemplateSource implements ExtensionPoint {
+    public static List<PodTemplate> getAll(@Nonnull KubernetesCloud cloud) {
+        return ExtensionList.lookup(PodTemplateSource.class)
+                .stream()
+                .map(s -> s.getList(cloud))
+                .flatMap(Collection::stream)
+                .collect(toList());
+    }
+
+    /**
+     * The list of {@link PodTemplate} contributed by this implementation.
+     * @return The list of {@link PodTemplate} contributed by this implementation.
+     * @param cloud
+     */
+    @Nonnull
+    protected abstract List<PodTemplate> getList(@Nonnull KubernetesCloud cloud);
+}

src/main/java/org/csanchez/jenkins/plugins/kubernetes/pipeline/PodTemplateMap.java

@@ -10,6 +10,7 @@
 
 import org.csanchez.jenkins.plugins.kubernetes.KubernetesCloud;
 import org.csanchez.jenkins.plugins.kubernetes.PodTemplate;
+import org.csanchez.jenkins.plugins.kubernetes.PodTemplateSource;
 
 import hudson.Extension;
 import hudson.ExtensionList;
@@ -62,4 +63,14 @@ public void removeTemplate(@Nonnull KubernetesCloud cloud, @Nonnull PodTemplate
         getOrCreateTemplateList(cloud).remove(podTemplate);
     }
 
+    @Extension
+    public static class PodTemplateSourceImpl extends PodTemplateSource {
+
+        @Nonnull
+        @Override
+        public List<PodTemplate> getList(@Nonnull KubernetesCloud cloud) {
+            return PodTemplateMap.get().getTemplates(cloud);
+        }
+    }
+
 }