HONEYCOMB-207 : Configurable modules list for distributions

Export list of modules for built distribution on compile time according
to distribution.modules property to ***module-config.txt
Load aggregated set of modules on start from all descriptors in /modules
folder

Change-Id: Icdeb23536aee3a243a221d3f2ec5f340d387764e
Signed-off-by: Jan Srnicek <jsrnicek@cisco.com>

2 files changed, 165 insertions, 25 deletions

diff --git a/infra/minimal-distribution/src/main/java/io/fd/honeycomb/infra/distro/ActiveModuleProvider.java b/infra/minimal-distribution/src/main/java/io/fd/honeycomb/infra/distro/ActiveModuleProvider.java
new file mode 100644
index 000000000..03c56969d
--- /dev/null
+++ b/infra/minimal-distribution/src/main/java/io/fd/honeycomb/infra/distro/ActiveModuleProvider.java
@@ -0,0 +1,154 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.fd.honeycomb.infra.distro;
+
+import com.google.common.collect.ImmutableList;
+import com.google.inject.Module;
+import java.io.File;
+import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.URL;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import javax.annotation.Nonnull;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Provides list of active modules for distribution
+ */
+public class ActiveModuleProvider {
+
+    public static final String STANDARD_MODULES_RELATIVE_PATH = "../modules/";
+    private static final Logger LOG = LoggerFactory.getLogger(ActiveModuleProvider.class);
+
+    /**
+     * Provide unique set of active modules filtered from provided resources
+     */
+    public static Set<Module> loadActiveModules(@Nonnull final List<String> moduleNames) {
+        final ClassLoader classLoader = ActiveModuleProvider.class.getClassLoader();
+        LOG.info("Reading active modules configuration for distribution");
+
+        // process resources to resource modules
+        return moduleNames.stream()
+                .map(String::trim)
+                .filter(trimmedLine -> trimmedLine.length() != 0)
+                // filter out commented lines
+                .filter(nonEmptyLine -> !nonEmptyLine.startsWith("//"))
+                // filter duplicates
+                .distinct()
+                .map(validLine -> nameToClass(validLine, classLoader))
+                // filters out classes that are not modules
+                .filter(ActiveModuleProvider::filterNonModules)
+                .map(ActiveModuleProvider::classToInstance)
+                .collect(Collectors.toSet());
+    }
+
+    /**
+     * Aggregate all resources from provided relative path into a {@code List<String>}
+     */
+    public static List<String> aggregateResources(final String relativePath, final ClassLoader classLoader) {
+        try {
+            return Collections.list(classLoader.getResources(relativePath)).stream()
+                    .map(ActiveModuleProvider::toURI)
+                    .flatMap(ActiveModuleProvider::folderToFile)
+                    .map(File::toURI)
+                    .map(Paths::get)
+                    // readAll lines and add them to iteration
+                    .flatMap(ActiveModuleProvider::readLines)
+                    .collect(Collectors.toList());
+        } catch (IOException e) {
+            LOG.error("Unable to load resources from relative path {}", relativePath, e);
+            throw new IllegalStateException("Unable to load resources from relative path " + relativePath, e);
+        }
+    }
+
+    private static Stream<File> folderToFile(final URI uri) {
+        final File[] files = new File(uri).listFiles(File::isFile);
+
+        return files != null
+                ? ImmutableList.copyOf(files).stream()
+                : Collections.<File>emptyList().stream();
+    }
+
+    private static boolean filterNonModules(final Class<?> clazz) {
+        final boolean isModule = Module.class.isAssignableFrom(clazz);
+        if (!isModule) {
+            LOG.warn("Class {} is provided in modules configuration, but is not a Module and will be ignored", clazz);
+        }
+        return isModule;
+    }
+
+    /**
+     * Read lines from {@code Path}
+     */
+    private static Stream<String> readLines(final Path path) {
+        try {
+            return Files.readAllLines(path).stream();
+        } catch (IOException e) {
+            LOG.error("Unable to read content of {}", path, e);
+            throw new IllegalStateException("Unable to read content of " + path, e);
+        }
+    }
+
+    /**
+     * Converts {@code URL} to {@code URI}
+     */
+    private static URI toURI(final URL url) {
+        try {
+            return url.toURI();
+        } catch (URISyntaxException e) {
+            LOG.error("Unable to convert {} to uri", url);
+            throw new IllegalStateException("Unable to convert " + url + " to uri", e);
+        }
+    }
+
+    /**
+     * Loads class by provided name
+     */
+    private static Class<?> nameToClass(final String name,
+                                        final ClassLoader classLoader) {
+        try {
+            LOG.info("Loading module class {}", name);
+            return classLoader.loadClass(name);
+        } catch (ClassNotFoundException e) {
+            LOG.error("Unable to convert {} to class, make sure you've provided sources to classpath", name);
+            throw new IllegalStateException(
+                    "Unable to convert " + name + " to class, make sure you've provided sources to classpath", e);
+        }
+    }
+
+    /**
+     * Creates instance of module class
+     */
+    private static Module classToInstance(final Class<?> moduleClass) {
+        try {
+            LOG.info("Creating instance for module {}", moduleClass);
+            return Module.class.cast(moduleClass.newInstance());
+        } catch (InstantiationException | IllegalAccessException e) {
+            LOG.error("Unable to create instance for class {}", moduleClass, e);
+            throw new IllegalStateException("Unable to create instance for class" + moduleClass, e);
+        }
+    }
+}
diff --git a/infra/minimal-distribution/src/main/java/io/fd/honeycomb/infra/distro/Main.java b/infra/minimal-distribution/src/main/java/io/fd/honeycomb/infra/distro/Main.java
index d3a562d3a..3c62382c2 100644
--- a/infra/minimal-distribution/src/main/java/io/fd/honeycomb/infra/distro/Main.java
+++ b/infra/minimal-distribution/src/main/java/io/fd/honeycomb/infra/distro/Main.java
@@ -16,8 +16,11 @@
 
 package io.fd.honeycomb.infra.distro;
 
+import static io.fd.honeycomb.infra.distro.ActiveModuleProvider.STANDARD_MODULES_RELATIVE_PATH;
+import static io.fd.honeycomb.infra.distro.ActiveModuleProvider.aggregateResources;
+import static io.fd.honeycomb.infra.distro.ActiveModuleProvider.loadActiveModules;
+
 import com.google.common.base.Preconditions;
-import com.google.common.collect.ImmutableList;
 import com.google.inject.ConfigurationException;
 import com.google.inject.CreationException;
 import com.google.inject.Guice;
@@ -28,20 +31,14 @@ import com.google.inject.ProvisionException;
 import com.google.inject.name.Names;
 import io.fd.honeycomb.data.init.DataTreeInitializer;
 import io.fd.honeycomb.data.init.InitializerRegistry;
-import io.fd.honeycomb.infra.distro.cfgattrs.CfgAttrsModule;
 import io.fd.honeycomb.infra.distro.cfgattrs.HoneycombConfiguration;
-import io.fd.honeycomb.infra.distro.data.ConfigAndOperationalPipelineModule;
-import io.fd.honeycomb.infra.distro.data.context.ContextPipelineModule;
 import io.fd.honeycomb.infra.distro.initializer.InitializerPipelineModule;
 import io.fd.honeycomb.infra.distro.netconf.HoneycombNotification2NetconfProvider;
 import io.fd.honeycomb.infra.distro.netconf.NetconfModule;
-import io.fd.honeycomb.infra.distro.netconf.NetconfReadersModule;
 import io.fd.honeycomb.infra.distro.netconf.NetconfSshServerProvider;
 import io.fd.honeycomb.infra.distro.netconf.NetconfTcpServerProvider;
 import io.fd.honeycomb.infra.distro.restconf.RestconfModule;
-import io.fd.honeycomb.infra.distro.schema.SchemaModule;
-import io.fd.honeycomb.infra.distro.schema.YangBindingProviderModule;
-import java.util.List;
+import java.util.Set;
 import org.eclipse.jetty.server.Server;
 import org.eclipse.jetty.server.ServerConnector;
 import org.opendaylight.netconf.mapping.api.NetconfOperationServiceFactory;
@@ -53,29 +50,18 @@ public final class Main {
 
     private static final Logger LOG = LoggerFactory.getLogger(Main.class);
 
-    public static final List<Module> BASE_MODULES = ImmutableList.of(
-            // Infra
-            new YangBindingProviderModule(),
-            new SchemaModule(),
-            new ConfigAndOperationalPipelineModule(),
-            new ContextPipelineModule(),
-            new InitializerPipelineModule(),
-            new NetconfModule(),
-            new NetconfReadersModule(),
-            new RestconfModule(),
-            // Json config attributes
-            new CfgAttrsModule());
-
-    private Main() {}
+    private Main() {
+    }
 
     public static void main(String[] args) {
-        init(BASE_MODULES);
+        final ClassLoader classLoader = Main.class.getClassLoader();
+        init(loadActiveModules(aggregateResources(STANDARD_MODULES_RELATIVE_PATH, classLoader)));
     }
 
     /**
-     * Initialize the Honeycomb infrastructure + all wired plugins.
+     * Initialize the Honeycomb with provided modules
      */
-    public static Injector init(final List<? extends Module> modules) {
+    public static Injector init(final Set<? extends Module> modules) {
         try {
             LOG.info("Starting honeycomb");
             Injector injector = Guice.createInjector(modules);