Build: add the ability to support plugins in BWC tests

This commit adds the ability to support running with plugins in tests that make use of
backwards compatibility nodes. This can be used to test rolling upgrades with plugins
to ensure they do not cause issues during a rolling upgrade of elasticsearch.

buildSrc/src/main/groovy/org/elasticsearch/gradle/test/ClusterFormationTasks.groovy

@@ -23,6 +23,7 @@ import org.apache.tools.ant.taskdefs.condition.Os
 import org.elasticsearch.gradle.LoggedExec
 import org.elasticsearch.gradle.VersionProperties
 import org.elasticsearch.gradle.plugin.PluginBuildPlugin
+import org.elasticsearch.gradle.plugin.PluginPropertiesExtension
 import org.gradle.api.AntBuilder
 import org.gradle.api.DefaultTask
 import org.gradle.api.GradleException
@@ -30,6 +31,7 @@ import org.gradle.api.InvalidUserDataException
 import org.gradle.api.Project
 import org.gradle.api.Task
 import org.gradle.api.artifacts.Configuration
+import org.gradle.api.artifacts.Dependency
 import org.gradle.api.file.FileCollection
 import org.gradle.api.logging.Logger
 import org.gradle.api.tasks.Copy
@@ -82,12 +84,17 @@ class ClusterFormationTasks {
             // from mirrors using gradles built-in mechanism etc.
             project.configurations {
                 elasticsearchBwcDistro
+                elasticsearchBwcPlugins
             }
             configureDistributionDependency(project, config.distribution, project.configurations.elasticsearchBwcDistro, config.bwcVersion)
+            for (Map.Entry<String, Project> entry : config.plugins.entrySet()) {
+                configureBwcPluginDependency("${task.name}_elasticsearchBwcPlugins", project, entry.getValue(),
+                        project.configurations.elasticsearchBwcPlugins, config.bwcVersion)
+            }
         }
         for (int i = 0; i < config.numNodes; i++) {
             // we start N nodes and out of these N nodes there might be M bwc nodes.
-            // for each of those nodes we might have a different configuratioon
+            // for each of those nodes we might have a different configuration
             String elasticsearchVersion = VersionProperties.elasticsearch
             Configuration distro = currentDistro
             if (i < config.numBwcNodes) {
@@ -116,6 +123,13 @@ class ClusterFormationTasks {
         project.dependencies.add(configuration.name, "org.elasticsearch.distribution.${distro}:elasticsearch:${elasticsearchVersion}@${packaging}")
     }
 
+    /** Adds a dependency on a different version of the given plugin, which will be retrieved using gradle's dependency resolution */
+    static void configureBwcPluginDependency(String name, Project project, Project pluginProject, Configuration configuration, String elasticsearchVersion) {
+        verifyProjectHasBuildPlugin(name, elasticsearchVersion, project, pluginProject)
+        PluginPropertiesExtension extension = pluginProject.extensions.findByName('esplugin');
+        project.dependencies.add(configuration.name, "org.elasticsearch.plugin:${extension.name}:${elasticsearchVersion}@zip")
+    }
+
     /**
      * Adds dependent tasks to start an elasticsearch cluster before the given task is executed,
      * and stop it after it has finished executing.
@@ -147,7 +161,13 @@ class ClusterFormationTasks {
         setup = configureStopTask(taskName(task, node, 'stopPrevious'), project, setup, node)
         setup = configureExtractTask(taskName(task, node, 'extract'), project, setup, node, configuration)
         setup = configureWriteConfigTask(taskName(task, node, 'configure'), project, setup, node, seedNode)
-        setup = configureCopyPluginsTask(taskName(task, node, 'copyPlugins'), project, setup, node)
+        if (node.config.plugins.isEmpty() == false) {
+            if (node.nodeVersion == VersionProperties.elasticsearch) {
+                setup = configureCopyPluginsTask(taskName(task, node, 'copyPlugins'), project, setup, node)
+            } else {
+                setup = configureCopyBwcPluginsTask(taskName(task, node, 'copyBwcPlugins'), project, setup, node)
+            }
+        }
 
         // install modules
         for (Project module : node.config.modules) {
@@ -317,18 +337,13 @@ class ClusterFormationTasks {
      * to the test resources for this project.
      */
     static Task configureCopyPluginsTask(String name, Project project, Task setup, NodeInfo node) {
-        if (node.config.plugins.isEmpty()) {
-            return setup
-        }
         Copy copyPlugins = project.tasks.create(name: name, type: Copy, dependsOn: setup)
 
         List<FileCollection> pluginFiles = []
         for (Map.Entry<String, Project> plugin : node.config.plugins.entrySet()) {
 
             Project pluginProject = plugin.getValue()
-            if (pluginProject.plugins.hasPlugin(PluginBuildPlugin) == false) {
-                throw new GradleException("Task ${name} cannot project ${pluginProject.path} which is not an esplugin")
-            }
+            verifyProjectHasBuildPlugin(name, node.nodeVersion, project, pluginProject)
             String configurationName = "_plugin_${pluginProject.path}"
             Configuration configuration = project.configurations.findByName(configurationName)
             if (configuration == null) {
@@ -358,6 +373,31 @@ class ClusterFormationTasks {
         return copyPlugins
     }
 
+    /** Configures task to copy a plugin based on a zip file resolved using dependencies for an older version */
+    static Task configureCopyBwcPluginsTask(String name, Project project, Task setup, NodeInfo node) {
+        for (Map.Entry<String, Project> plugin : node.config.plugins.entrySet()) {
+            Project pluginProject = plugin.getValue()
+            verifyProjectHasBuildPlugin(name, node.nodeVersion, project, pluginProject)
+            String configurationName = "_plugin_bwc_${pluginProject.path}"
+            Configuration configuration = project.configurations.findByName(configurationName)
+            if (configuration == null) {
+                configuration = project.configurations.create(configurationName)
+            }
+
+            final String depName = pluginProject.extensions.findByName('esplugin').name
+            Dependency dep = project.configurations.elasticsearchBwcPlugins.dependencies.find {
+                it.name == depName
+            }
+            configuration.dependencies.add(dep)
+        }
+
+        Copy copyPlugins = project.tasks.create(name: name, type: Copy, dependsOn: setup) {
+            from project.configurations.elasticsearchBwcPlugins
+            into node.pluginsTmpDir
+        }
+        return copyPlugins
+    }
+
     static Task configureInstallModuleTask(String name, Project project, Task setup, NodeInfo node, Project module) {
         if (node.config.distribution != 'integ-test-zip') {
             throw new GradleException("Module ${module.path} not allowed be installed distributions other than integ-test-zip because they should already have all modules bundled!")
@@ -373,7 +413,12 @@ class ClusterFormationTasks {
     }
 
     static Task configureInstallPluginTask(String name, Project project, Task setup, NodeInfo node, Project plugin) {
-        FileCollection pluginZip = project.configurations.getByName("_plugin_${plugin.path}")
+        final FileCollection pluginZip;
+        if (node.nodeVersion != VersionProperties.elasticsearch) {
+            pluginZip = project.configurations.getByName("_plugin_bwc_${plugin.path}")
+        } else {
+            pluginZip = project.configurations.getByName("_plugin_${plugin.path}")
+        }
         // delay reading the file location until execution time by wrapping in a closure within a GString
         Object file = "${-> new File(node.pluginsTmpDir, pluginZip.singleFile.getName()).toURI().toURL().toString()}"
         Object[] args = [new File(node.homeDir, 'bin/elasticsearch-plugin'), 'install', file]
@@ -623,4 +668,11 @@ class ClusterFormationTasks {
         project.ant.project.removeBuildListener(listener)
         return retVal
     }
+
+    static void verifyProjectHasBuildPlugin(String name, String version, Project project, Project pluginProject) {
+        if (pluginProject.plugins.hasPlugin(PluginBuildPlugin) == false) {
+            throw new GradleException("Task [${name}] cannot add plugin [${pluginProject.path}] with version [${version}] to project's " +
+                    "[${project.path}] dependencies: the plugin is not an esplugin")
+        }
+    }
 }

buildSrc/src/main/groovy/org/elasticsearch/gradle/test/NodeInfo.groovy

@@ -93,6 +93,9 @@ class NodeInfo {
     /** buffer for ant output when starting this node */
     ByteArrayOutputStream buffer = new ByteArrayOutputStream()
 
+    /** the version of elasticsearch that this node runs */
+    String nodeVersion
+
     /** Creates a node to run as part of a cluster for the given task */
     NodeInfo(ClusterConfiguration config, int nodeNum, Project project, Task task, String nodeVersion, File sharedDir) {
         this.config = config
@@ -105,6 +108,7 @@ class NodeInfo {
         }
         baseDir = new File(project.buildDir, "cluster/${task.name} node${nodeNum}")
         pidFile = new File(baseDir, 'es.pid')
+        this.nodeVersion = nodeVersion
         homeDir = homeDir(baseDir, config.distribution, nodeVersion)
         confDir = confDir(baseDir, config.distribution, nodeVersion)
         if (config.dataDir != null) {