[Backport release/1.8.x] Distributed event notification of GWC config changes

src/gwc/autoconfigure/src/main/java/org/geoserver/cloud/autoconfigure/gwc/backend/PgconfigGwcInitializer.java

@@ -7,12 +7,13 @@
 import lombok.NonNull;
 import lombok.extern.slf4j.Slf4j;
 
+import org.geoserver.GeoServerConfigurationLock;
 import org.geoserver.cloud.gwc.backend.pgconfig.PgconfigTileLayerCatalog;
-import org.geoserver.cloud.gwc.config.core.AbstractGwcInitializer;
 import org.geoserver.cloud.gwc.event.TileLayerEvent;
 import org.geoserver.cloud.gwc.repository.GeoServerTileLayerConfiguration;
 import org.geoserver.config.GeoServerReinitializer;
 import org.geoserver.gwc.ConfigurableBlobStore;
+import org.geoserver.gwc.config.AbstractGwcInitializer;
 import org.geoserver.gwc.config.GWCConfigPersister;
 import org.geoserver.gwc.config.GWCInitializer;
 import org.geoserver.gwc.layer.TileLayerCatalog;
@@ -46,8 +47,9 @@ class PgconfigGwcInitializer extends AbstractGwcInitializer {
     public PgconfigGwcInitializer(
             @NonNull GWCConfigPersister configPersister,
             @NonNull ConfigurableBlobStore blobStore,
-            @NonNull GeoServerTileLayerConfiguration geoseverTileLayers) {
-        super(configPersister, blobStore, geoseverTileLayers);
+            @NonNull GeoServerTileLayerConfiguration geoseverTileLayers,
+            @NonNull GeoServerConfigurationLock configLock) {
+        super(configPersister, blobStore, geoseverTileLayers, configLock);
     }
 
     @Override

src/gwc/autoconfigure/src/main/java/org/geoserver/cloud/autoconfigure/gwc/backend/PgconfigTileLayerCatalogAutoConfiguration.java

@@ -7,6 +7,7 @@
 import lombok.NonNull;
 import lombok.extern.slf4j.Slf4j;
 
+import org.geoserver.GeoServerConfigurationLock;
 import org.geoserver.catalog.Catalog;
 import org.geoserver.cloud.autoconfigure.catalog.backend.pgconfig.ConditionalOnPgconfigBackendEnabled;
 import org.geoserver.cloud.autoconfigure.catalog.backend.pgconfig.PgconfigDataSourceAutoConfiguration;
@@ -58,13 +59,18 @@ void log() {
         log.info("GeoWebCache TileLayerCatalog using PostgreSQL config backend");
     }
 
-    /** Replacement for {@link GWCInitializer} when using {@link GeoServerTileLayerConfiguration} */
+    /**
+     * Replacement for {@link GWCInitializer} when using {@link GeoServerTileLayerConfiguration}
+     *
+     * @param configLock
+     */
     @Bean
     PgconfigGwcInitializer gwcInitializer(
             GWCConfigPersister configPersister,
             ConfigurableBlobStore blobStore,
-            GeoServerTileLayerConfiguration tileLayerCatalog) {
-        return new PgconfigGwcInitializer(configPersister, blobStore, tileLayerCatalog);
+            GeoServerTileLayerConfiguration tileLayerCatalog,
+            GeoServerConfigurationLock configLock) {
+        return new PgconfigGwcInitializer(configPersister, blobStore, tileLayerCatalog, configLock);
     }
 
     @Bean(name = "gwcCatalogConfiguration")

src/gwc/autoconfigure/src/test/java/org/geoserver/cloud/autoconfigure/gwc/core/GwcCoreAutoConfigurationTest.java

@@ -17,8 +17,15 @@
 import org.geoserver.cloud.gwc.repository.CloudDefaultStorageFinder;
 import org.geoserver.cloud.gwc.repository.CloudGwcXmlConfiguration;
 import org.geoserver.cloud.gwc.repository.CloudXMLResourceProvider;
+import org.geoserver.gwc.ConfigurableLockProvider;
+import org.geoserver.gwc.GWC;
+import org.geoserver.gwc.GeoServerLockProvider;
+import org.geoserver.gwc.config.AbstractGwcInitializer;
 import org.geoserver.gwc.config.DefaultGwcInitializer;
+import org.geoserver.gwc.config.GWCConfig;
+import org.geoserver.gwc.config.GWCConfigPersister;
 import org.geoserver.platform.GeoServerExtensionsHelper;
+import org.geowebcache.locks.LockProvider;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
@@ -65,6 +72,35 @@ void defaultCacheDirectoryIsAFile(@TempDir File tmpDir) throws IOException {
         assertContextLoadFails(BeanInitializationException.class, "is not a directory");
     }
 
+    @Test
+    void lockProviderDelegatesStoGeoSeverLockProvider() {
+        runner.run(
+                context -> {
+                    GeoServerExtensionsHelper.init(context);
+                    assertThat(context)
+                            .hasNotFailed()
+                            .hasBean(AbstractGwcInitializer.GWC_LOCK_PROVIDER_BEAN_NAME)
+                            .getBean(AbstractGwcInitializer.GWC_LOCK_PROVIDER_BEAN_NAME)
+                            .isInstanceOf(GeoServerLockProvider.class);
+
+                    GWCConfigPersister persister = context.getBean(GWCConfigPersister.class);
+                    GWCConfig config = persister.getConfig();
+                    assertThat(config.getLockProviderName())
+                            .isEqualTo(AbstractGwcInitializer.GWC_LOCK_PROVIDER_BEAN_NAME);
+
+                    GWC gwc = GWC.get();
+
+                    LockProvider lockProvider = gwc.getLockProvider();
+                    assertThat(lockProvider).isInstanceOf(ConfigurableLockProvider.class);
+                    GeoServerLockProvider expected =
+                            context.getBean(
+                                    AbstractGwcInitializer.GWC_LOCK_PROVIDER_BEAN_NAME,
+                                    GeoServerLockProvider.class);
+                    assertThat(((ConfigurableLockProvider) lockProvider).getDelegate())
+                            .isSameAs(expected);
+                });
+    }
+
     @Test
     void contextLoads() {
         runner.run(

src/gwc/core/src/main/java/org/geoserver/cloud/gwc/config/core/GeoServerIntegrationConfiguration.java

@@ -7,6 +7,13 @@
 import lombok.extern.slf4j.Slf4j;
 
 import org.geoserver.cloud.config.factory.FilteringXmlBeanDefinitionReader;
+import org.geoserver.cloud.gwc.event.ConfigChangeEvent;
+import org.geoserver.config.util.XStreamPersisterFactory;
+import org.geoserver.gwc.config.CloudGwcConfigPersister;
+import org.geoserver.gwc.config.GWCConfigPersister;
+import org.geoserver.platform.GeoServerResourceLoader;
+import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.ImportResource;
 
@@ -32,6 +39,7 @@ public class GeoServerIntegrationConfiguration {
             |gwcTransactionListener\
             |gwcWMSExtendedCapabilitiesProvider\
             |gwcInitializer\
+            |gwcGeoServervConfigPersister\
             ).*$\
             """;
 
@@ -42,4 +50,20 @@ public class GeoServerIntegrationConfiguration {
     public void log() {
         log.info("GeoWebCache core GeoServer integration enabled");
     }
+
+    /**
+     * Overrides {@code gwcGeoServervConfigPersister} with a cluster-aware {@link
+     * GWCConfigPersister} that sends {@link ConfigChangeEvent}s upon {@link
+     * GWCConfigPersister#save(org.geoserver.gwc.config.GWCConfig)}
+     *
+     * @param xsfp
+     * @param resourceLoader
+     */
+    @Bean
+    GWCConfigPersister gwcGeoServervConfigPersister(
+            XStreamPersisterFactory xsfp,
+            GeoServerResourceLoader resourceLoader,
+            ApplicationEventPublisher publisher) {
+        return new CloudGwcConfigPersister(xsfp, resourceLoader, publisher::publishEvent);
+    }
 }

src/gwc/core/src/main/java/org/geoserver/cloud/gwc/config/core/GeoWebCacheCoreConfiguration.java

@@ -14,12 +14,15 @@
 import org.geoserver.cloud.gwc.repository.CloudDefaultStorageFinder;
 import org.geoserver.cloud.gwc.repository.CloudGwcXmlConfiguration;
 import org.geoserver.cloud.gwc.repository.CloudXMLResourceProvider;
+import org.geoserver.gwc.GeoServerLockProvider;
+import org.geoserver.gwc.config.AbstractGwcInitializer;
 import org.geoserver.platform.resource.Resource;
 import org.geoserver.platform.resource.ResourceStore;
 import org.geoserver.platform.resource.Resources;
 import org.geowebcache.config.ConfigurationResourceProvider;
 import org.geowebcache.config.XMLConfiguration;
 import org.geowebcache.config.XMLFileResourceProvider;
+import org.geowebcache.locks.LockProvider;
 import org.geowebcache.storage.DefaultStorageFinder;
 import org.geowebcache.util.ApplicationContextProvider;
 import org.springframework.beans.FatalBeanException;
@@ -56,11 +59,22 @@
 @ImportResource(
         reader = FilteringXmlBeanDefinitionReader.class, //
         locations = {
-            "jar:gs-gwc-[0-9]+.*!/geowebcache-core-context.xml#name=^(?!gwcXmlConfig|gwcDefaultStorageFinder|gwcGeoServervConfigPersister|metastoreRemover).*$"
+            "jar:gs-gwc-[0-9]+.*!/geowebcache-core-context.xml#name=^(?!gwcXmlConfig|gwcDefaultStorageFinder|metastoreRemover).*$"
         })
 @Slf4j(topic = "org.geoserver.cloud.gwc.config.core")
 public class GeoWebCacheCoreConfiguration {
 
+    /**
+     * @return a {@link GeoServerLockProvider} delegating the the {@link ResourceStore}, whose
+     *     {@link ResourceStore#getLockProvider()} is known to be cluster-capable
+     */
+    @Bean(name = AbstractGwcInitializer.GWC_LOCK_PROVIDER_BEAN_NAME)
+    LockProvider gwcLockProvider(@Qualifier("resourceStoreImpl") ResourceStore resourceStore) {
+        var provider = new GeoServerLockProvider();
+        provider.setDelegate(resourceStore);
+        return provider;
+    }
+
     @Bean
     SetRequestPathInfoFilter setRequestPathInfoFilter() {
         return new SetRequestPathInfoFilter();
@@ -283,9 +297,12 @@ public void doFilter(ServletRequest request, ServletResponse response, FilterCha
          * </ul>
          */
         protected ServletRequest adaptRequest(HttpServletRequest request) {
-            // full request URI (e.g. '/geoserver/cloud/{workspace}/gwc/service/tms/1.0.0', where
-            // '/geoserver/cloud' is the context path as given by the gateway's base uri, and
-            // '/{workspace}/gwc' the suffix after which comes the pathInfo '/service/tms/1.0.0')
+            // full request URI (e.g. '/geoserver/cloud/{workspace}/gwc/service/tms/1.0.0',
+            // where
+            // '/geoserver/cloud' is the context path as given by the gateway's base uri,
+            // and
+            // '/{workspace}/gwc' the suffix after which comes the pathInfo
+            // '/service/tms/1.0.0')
             final String requestURI = request.getRequestURI();
 
             final String gwc = "/gwc";

src/gwc/core/src/main/java/org/geoserver/cloud/gwc/event/ConfigChangeEvent.java

@@ -0,0 +1,16 @@
+package org.geoserver.cloud.gwc.event;
+
+@SuppressWarnings("serial")
+public class ConfigChangeEvent extends GeoWebCacheEvent {
+
+    public static final String OBJECT_ID = "gwcConfig";
+
+    public ConfigChangeEvent(Object source) {
+        super(source, Type.MODIFIED);
+    }
+
+    @Override
+    protected String getObjectId() {
+        return OBJECT_ID;
+    }
+}

src/gwc/core/src/main/java/org/geoserver/cloud/gwc/config/core/AbstractGwcInitializer.java → src/gwc/core/src/main/java/org/geoserver/gwc/config/AbstractGwcInitializer.java

@@ -2,7 +2,7 @@
  * (c) 2024 Open Source Geospatial Foundation - all rights reserved This code is licensed under the
  * GPL 2.0 license, available at the root application directory.
  */
-package org.geoserver.cloud.gwc.config.core;
+package org.geoserver.gwc.config;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
@@ -11,21 +11,25 @@
 import lombok.NonNull;
 import lombok.RequiredArgsConstructor;
 
+import org.geoserver.GeoServerConfigurationLock;
+import org.geoserver.GeoServerConfigurationLock.LockType;
 import org.geoserver.cloud.gwc.event.TileLayerEvent;
 import org.geoserver.cloud.gwc.repository.GeoServerTileLayerConfiguration;
 import org.geoserver.config.GeoServer;
 import org.geoserver.config.GeoServerReinitializer;
 import org.geoserver.gwc.ConfigurableBlobStore;
-import org.geoserver.gwc.config.GWCConfig;
-import org.geoserver.gwc.config.GWCConfigPersister;
-import org.geoserver.gwc.config.GWCInitializer;
+import org.geoserver.gwc.GWC;
 import org.geoserver.gwc.layer.GeoServerTileLayer;
 import org.geoserver.gwc.layer.TileLayerCatalog;
+import org.geoserver.platform.resource.Resource;
+import org.geoserver.platform.resource.Resources;
 import org.geowebcache.layer.TileLayer;
+import org.geowebcache.locks.LockProvider;
 import org.geowebcache.storage.blobstore.memory.CacheConfiguration;
 import org.geowebcache.storage.blobstore.memory.CacheProvider;
 import org.geowebcache.storage.blobstore.memory.guava.GuavaCacheProvider;
 import org.slf4j.Logger;
+import org.springframework.beans.factory.InitializingBean;
 import org.springframework.context.event.EventListener;
 import org.springframework.util.StringUtils;
 
@@ -54,14 +58,28 @@
  * @since 1.8
  */
 @RequiredArgsConstructor
-public abstract class AbstractGwcInitializer implements GeoServerReinitializer {
+public abstract class AbstractGwcInitializer implements GeoServerReinitializer, InitializingBean {
+
+    /**
+     * {@link GWC#saveConfig(GWCConfig)} will lookup for the {@link LockProvider} named after {@link
+     * GWCConfig#getLockProviderName()}. We need it to be a cluster-aware lock provider. This is the
+     * bean name to be registered by the configuration, and we'll set it to {@link
+     * GWCConfig#setLockProviderName(String)} during initialization.
+     */
+    public static final String GWC_LOCK_PROVIDER_BEAN_NAME = "gwcClusteringLockProvider";
 
     protected final @NonNull GWCConfigPersister configPersister;
     protected final @NonNull ConfigurableBlobStore blobStore;
     protected final @NonNull GeoServerTileLayerConfiguration geoseverTileLayers;
+    protected final @NonNull GeoServerConfigurationLock globalConfigLock;
 
     protected abstract Logger logger();
 
+    @Override
+    public void afterPropertiesSet() throws IOException {
+        initializeGeoServerIntegrationConfigFile();
+    }
+
     /**
      * @see org.geoserver.config.GeoServerInitializer#initialize(org.geoserver.config.GeoServer)
      */
@@ -80,6 +98,58 @@ public void initialize(final GeoServer geoServer) throws Exception {
         setUpNonMemoryCacheableLayers();
     }
 
+    /**
+     * Initialize the datadir/gs-gwc.xml file before {@link
+     * #initialize(org.geoserver.config.GeoServer) super.initialize(GeoServer)}
+     */
+    private void initializeGeoServerIntegrationConfigFile() throws IOException {
+        globalConfigLock.lock(LockType.WRITE);
+        try {
+            if (configFileExists()) {
+                updateLockProviderName();
+            } else {
+                logger().info(
+                                "Initializing GeoServer specific GWC configuration {}",
+                                configPersister.findConfigFile());
+                GWCConfig defaults = new GWCConfig();
+                defaults.setVersion("1.1.0");
+                defaults.setLockProviderName(GWC_LOCK_PROVIDER_BEAN_NAME);
+                configPersister.save(defaults);
+            }
+        } finally {
+            globalConfigLock.unlock();
+        }
+    }
+
+    /**
+     * In case the {@link GWCConfig} exists and its lock provider name is not {@link
+     * #GWC_LOCK_PROVIDER_BEAN_NAME}, updates and saves the configuration.
+     *
+     * <p>At this point, {@link #configFileExists()} is known to be true.
+     */
+    private void updateLockProviderName() throws IOException {
+        final GWCConfig gwcConfig = configPersister.getConfig();
+        if (!GWC_LOCK_PROVIDER_BEAN_NAME.equals(gwcConfig.getLockProviderName())) {
+            if (null == gwcConfig.getLockProviderName()) {
+                logger().info(
+                                "Setting GeoWebCache lock provider to {}",
+                                GWC_LOCK_PROVIDER_BEAN_NAME);
+            } else {
+                logger().warn(
+                                "Updating GeoWebCache lock provider from {} to {}",
+                                gwcConfig.getLockProviderName(),
+                                GWC_LOCK_PROVIDER_BEAN_NAME);
+            }
+            gwcConfig.setLockProviderName(GWC_LOCK_PROVIDER_BEAN_NAME);
+            configPersister.save(gwcConfig);
+        }
+    }
+
+    private boolean configFileExists() throws IOException {
+        Resource configFile = configPersister.findConfigFile();
+        return Resources.exists(configFile);
+    }
+
     @EventListener(TileLayerEvent.class)
     void onTileLayerEvent(TileLayerEvent event) {
         cacheProvider().ifPresent(cache -> onTileLayerEvent(event, cache));