Add ignored paths for config monitor

docs/modules/ROOT/pages/server/push-notifications-and-bus.adoc

@@ -16,6 +16,43 @@ The default configuration works out of the box with Github, Gitlab, Gitea, Gitee
 In addition to the JSON notifications from Github, Gitlab, Gitee, or Bitbucket, you can trigger a change notification by POSTing to `/monitor` with form-encoded body parameters in the pattern of `path=\{application}`.
 Doing so broadcasts to applications matching the `\{application}` pattern (which can contain wildcards).
 
+[[ignored-monitor-paths]]
+== Ignoring Paths
+
+You can configure the Config Server to ignore specific paths when processing webhook notifications by setting `spring.cloud.config.server.monitor.ignored-paths` to a list of regular expressions.
+
+Ignored paths are excluded before the Config Server determines which applications should be refreshed. This can be useful when a repository contains files that should not trigger configuration refreshes.
+
+For example:
+
+[source,yaml]
+----
+spring:
+  cloud:
+    config:
+      server:
+        monitor:
+          ignored-paths:
+            - "docker-compose/.*"
+            - "docs/.*"
+----
+
+Each regular expression is matched against the complete webhook path. A path is ignored when it matches any configured expression.
+
+By default, the Config Server processes at most 20 paths from a single notification. You can change this limit with `spring.cloud.config.server.monitor.max-paths`. If a notification contains more paths than the configured maximum, the remaining paths are not processed and a warning is logged.
+
+For example:
+
+[source,yaml]
+----
+spring:
+  cloud:
+    config:
+      server:
+        monitor:
+          max-paths: 50
+----
+
 NOTE: The `RefreshRemoteApplicationEvent` is transmitted only if the `spring-cloud-bus` is activated in both the Config Server and in the client application.
 
 NOTE: The default configuration also detects filesystem changes in local git repositories. In that case, the webhook is not used. However, as soon as you edit a config file, a refresh is broadcast.

spring-cloud-config-monitor/src/main/java/org/springframework/cloud/config/monitor/EnvironmentMonitorAutoConfiguration.java

@@ -75,7 +75,8 @@ protected static class BusPropertyPathConfiguration {
 		public PropertyPathEndpoint propertyPathEndpoint(BusProperties busProperties,
 				MonitorConfigurationProperties monitorProperties) {
 			return new PropertyPathEndpoint(new CompositePropertyPathNotificationExtractor(this.extractors),
-					busProperties.getId(), monitorProperties.getMaxDashes());
+					busProperties.getId(), monitorProperties.getMaxDashes(), monitorProperties.getMaxPaths(),
+					monitorProperties.getIgnoredPaths());
 		}
 
 		// TODO: With the current implementation bus can't be disabled
@@ -85,7 +86,8 @@ public PropertyPathEndpoint noBusBeanPropertyPathEndpoint(
 				@Value("${spring.cloud.bus.id:application}") String id,
 				MonitorConfigurationProperties monitorProperties) {
 			return new PropertyPathEndpoint(new CompositePropertyPathNotificationExtractor(this.extractors), id,
-					monitorProperties.getMaxDashes());
+					monitorProperties.getMaxDashes(), monitorProperties.getMaxPaths(),
+					monitorProperties.getIgnoredPaths());
 		}
 
 	}
@@ -99,7 +101,8 @@ public PropertyPathEndpoint noBusPropertyPathEndpoint(@Value("${spring.cloud.bus
 				@Autowired(required = false) List<PropertyPathNotificationExtractor> extractors,
 				MonitorConfigurationProperties monitorProperties) {
 			return new PropertyPathEndpoint(new CompositePropertyPathNotificationExtractor(extractors), id,
-					monitorProperties.getMaxDashes());
+					monitorProperties.getMaxDashes(), monitorProperties.getMaxPaths(),
+					monitorProperties.getIgnoredPaths());
 		}
 
 	}

spring-cloud-config-monitor/src/main/java/org/springframework/cloud/config/monitor/MonitorConfigurationProperties.java

@@ -16,6 +16,9 @@
 
 package org.springframework.cloud.config.monitor;
 
+import java.util.ArrayList;
+import java.util.List;
+
 import org.springframework.boot.context.properties.ConfigurationProperties;
 
 @ConfigurationProperties("spring.cloud.config.server.monitor")
@@ -27,6 +30,11 @@ public class MonitorConfigurationProperties {
 	 */
 	public static final int DEFAULT_MAX_DASHES = 20;
 
+	/**
+	 * Default maximum number of paths processed from a notification.
+	 */
+	public static final int DEFAULT_MAX_PATHS = 20;
+
 	private Endpoint endpoint = new Endpoint();
 
 	/**
@@ -36,6 +44,10 @@ public class MonitorConfigurationProperties {
 	 */
 	private int maxDashes = DEFAULT_MAX_DASHES;
 
+	private int maxPaths = DEFAULT_MAX_PATHS;
+
+	private List<String> ignoredPaths = new ArrayList<>();
+
 	private GitHub github = new GitHub();
 
 	private Gogs gogs = new Gogs();
@@ -112,6 +124,22 @@ public void setMaxDashes(int maxDashes) {
 		this.maxDashes = maxDashes;
 	}
 
+	public int getMaxPaths() {
+		return maxPaths;
+	}
+
+	public void setMaxPaths(int maxPaths) {
+		this.maxPaths = maxPaths;
+	}
+
+	public List<String> getIgnoredPaths() {
+		return ignoredPaths;
+	}
+
+	public void setIgnoredPaths(List<String> ignoredPaths) {
+		this.ignoredPaths = ignoredPaths;
+	}
+
 	public static class Endpoint {
 
 		private String path = "/monitor";

spring-cloud-config-monitor/src/main/java/org/springframework/cloud/config/monitor/PropertyPathEndpoint.java

@@ -22,6 +22,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.regex.Pattern;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -66,14 +67,32 @@ public class PropertyPathEndpoint implements ApplicationEventPublisherAware {
 	 */
 	private final int maxDashes;
 
+	/**
+	 * Upper bound on the number of paths processed from a notification. Prevents an
+	 * externally supplied notification from causing an unbounded amount of path
+	 * processing. Configurable via {@code spring.cloud.config.server.monitor.max-paths}.
+	 */
+	private final int maxPaths;
+
+	private final List<Pattern> ignoredPaths;
+
 	public PropertyPathEndpoint(PropertyPathNotificationExtractor extractor, String busId) {
-		this(extractor, busId, MonitorConfigurationProperties.DEFAULT_MAX_DASHES);
+		this(extractor, busId, MonitorConfigurationProperties.DEFAULT_MAX_DASHES,
+				MonitorConfigurationProperties.DEFAULT_MAX_PATHS, Collections.emptyList());
 	}
 
 	public PropertyPathEndpoint(PropertyPathNotificationExtractor extractor, String busId, int maxDashes) {
+		this(extractor, busId, maxDashes, MonitorConfigurationProperties.DEFAULT_MAX_PATHS, Collections.emptyList());
+	}
+
+	public PropertyPathEndpoint(PropertyPathNotificationExtractor extractor, String busId, int maxDashes, int maxPaths,
+			List<String> ignoredPaths) {
 		this.extractor = extractor;
 		this.busId = busId;
 		this.maxDashes = maxDashes;
+		this.maxPaths = maxPaths;
+		this.ignoredPaths = ignoredPaths == null ? Collections.emptyList()
+				: ignoredPaths.stream().map(Pattern::compile).toList();
 	}
 
 	/* for testing */ String getBusId() {
@@ -92,8 +111,19 @@ public Set<String> notifyByPath(@RequestHeader HttpHeaders headers, @RequestBody
 
 			Set<String> services = new LinkedHashSet<>();
 
-			for (String path : notification.getPaths()) {
-				services.addAll(guessServiceName(path));
+			String[] paths = notification.getPaths();
+			if (paths != null) {
+				int pathCount = Math.min(paths.length, this.maxPaths);
+				for (int i = 0; i < pathCount; i++) {
+					String path = paths[i];
+					if (!isIgnored(path)) {
+						services.addAll(guessServiceName(path));
+					}
+				}
+				if (paths.length > this.maxPaths) {
+					log.warn("Number of paths in notification exceeds the configured maximum of " + this.maxPaths
+							+ " (spring.cloud.config.server.monitor.max-paths); stopping path processing early");
+				}
 			}
 			if (this.applicationEventPublisher != null) {
 				for (String service : services) {
@@ -144,4 +174,8 @@ private Set<String> guessServiceName(String path) {
 		return services;
 	}
 
+	private boolean isIgnored(String path) {
+		return path != null && this.ignoredPaths.stream().anyMatch(pattern -> pattern.matcher(path).matches());
+	}
+
 }

spring-cloud-config-monitor/src/test/java/org/springframework/cloud/config/monitor/EnvironmentMonitorAutoConfigurationTests.java

@@ -67,6 +67,23 @@ public void testCanAddCustomPropertyPathNotificationExtractor() {
 		context.close();
 	}
 
+	@Test
+	public void testMonitorPathProperties() {
+		ConfigurableApplicationContext context = new SpringApplicationBuilder(BusConfig.class,
+				EnvironmentMonitorAutoConfiguration.class, TomcatServletWebServerAutoConfiguration.class,
+				ServerProperties.class, PropertyPlaceholderAutoConfiguration.class)
+			.properties("server.port=-1", "spring.cloud.config.server.monitor.max-paths=1",
+					"spring.cloud.config.server.monitor.ignored-paths=docker-compose/.*")
+			.run();
+
+		PropertyPathEndpoint endpoint = context.getBean(PropertyPathEndpoint.class);
+
+		assertThat(ReflectionTestUtils.getField(endpoint, "maxPaths")).isEqualTo(1);
+		assertThat((Collection<?>) ReflectionTestUtils.getField(endpoint, "ignoredPaths")).hasSize(1);
+
+		context.close();
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class BusConfig {
 

spring-cloud-config-monitor/src/test/java/org/springframework/cloud/config/monitor/PropertyPathEndpointTests.java

@@ -119,4 +119,37 @@ public void testNotifyLimitsDashes() {
 			.hasSize(2);
 	}
 
+	@Test
+	public void testNotifyIgnoresConfiguredPaths() {
+		PropertyPathEndpoint ignoredEndpoint = new PropertyPathEndpoint(
+				new CompositePropertyPathNotificationExtractor(Collections.emptyList()), "abc1", 20, 20,
+				Collections.singletonList("docker-compose/.*"));
+		StaticApplicationContext publisher = new StaticApplicationContext();
+		ignoredEndpoint.setApplicationEventPublisher(publisher);
+		publisher.refresh();
+
+		List<String> request = new ArrayList<>();
+		request.add("docker-compose/docker-compose.yml");
+		request.add("foo.yml");
+
+		assertThat(ignoredEndpoint.notifyByForm(new HttpHeaders(), request).toString()).isEqualTo("[foo]");
+	}
+
+	@Test
+	public void testNotifyLimitsPaths() {
+		PropertyPathEndpoint limitedEndpoint = new PropertyPathEndpoint(
+				new CompositePropertyPathNotificationExtractor(Collections.emptyList()), "abc1", 20, 2,
+				Collections.emptyList());
+		StaticApplicationContext publisher = new StaticApplicationContext();
+		limitedEndpoint.setApplicationEventPublisher(publisher);
+		publisher.refresh();
+
+		List<String> request = new ArrayList<>();
+		request.add("foo.yml");
+		request.add("bar.yml");
+		request.add("baz.yml");
+
+		assertThat(limitedEndpoint.notifyByForm(new HttpHeaders(), request).toString()).isEqualTo("[foo, bar]");
+	}
+
 }