Ignore trailing slash when recording Web metrics

Fixes gh-18207

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/MetricsProperties.java

@@ -243,6 +243,11 @@ public class MetricsProperties {
 				 */
 				private String metricName = "http.server.requests";
 
+				/**
+				 * Whether the trailing slash should be ignored when recording metrics.
+				 */
+				private boolean ignoreTrailingSlash = true;
+
 				/**
 				 * Auto-timed request settings.
 				 */
@@ -261,6 +266,14 @@ public class MetricsProperties {
 					this.metricName = metricName;
 				}
 
+				public boolean isIgnoreTrailingSlash() {
+					return this.ignoreTrailingSlash;
+				}
+
+				public void setIgnoreTrailingSlash(boolean ignoreTrailingSlash) {
+					this.ignoreTrailingSlash = ignoreTrailingSlash;
+				}
+
 			}
 
 		}

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/web/reactive/WebFluxMetricsAutoConfiguration.java

@@ -59,7 +59,8 @@ public class WebFluxMetricsAutoConfiguration {
 	@Bean
 	@ConditionalOnMissingBean(WebFluxTagsProvider.class)
 	public DefaultWebFluxTagsProvider webfluxTagConfigurer() {
-		return new DefaultWebFluxTagsProvider();
+		return new DefaultWebFluxTagsProvider(
+				this.properties.getWeb().getServer().getRequest().isIgnoreTrailingSlash());
 	}
 
 	@Bean

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/web/servlet/WebMvcMetricsAutoConfiguration.java

@@ -71,7 +71,7 @@ public class WebMvcMetricsAutoConfiguration {
 	@Bean
 	@ConditionalOnMissingBean(WebMvcTagsProvider.class)
 	public DefaultWebMvcTagsProvider webMvcTagsProvider() {
-		return new DefaultWebMvcTagsProvider();
+		return new DefaultWebMvcTagsProvider(this.properties.getWeb().getServer().getRequest().isIgnoreTrailingSlash());
 	}
 
 	@Bean

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/web/reactive/WebFluxMetricsAutoConfigurationTests.java

@@ -33,6 +33,7 @@ import org.springframework.boot.test.system.CapturedOutput;
 import org.springframework.boot.test.system.OutputCaptureExtension;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.test.util.ReflectionTestUtils;
 import org.springframework.test.web.reactive.server.WebTestClient;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -43,6 +44,7 @@ import static org.mockito.Mockito.mock;
  *
  * @author Brian Clozel
  * @author Dmytro Nosan
+ * @author Madhura Bhave
  */
 @ExtendWith(OutputCaptureExtension.class)
 class WebFluxMetricsAutoConfigurationTests {
@@ -55,9 +57,21 @@ class WebFluxMetricsAutoConfigurationTests {
 		this.contextRunner.run((context) -> {
 			assertThat(context).getBeans(MetricsWebFilter.class).hasSize(1);
 			assertThat(context).getBeans(DefaultWebFluxTagsProvider.class).hasSize(1);
+			assertThat(ReflectionTestUtils.getField(context.getBean(DefaultWebFluxTagsProvider.class),
+					"ignoreTrailingSlash")).isEqualTo(true);
 		});
 	}
 
+	@Test
+	void tagsProviderWhenIgnoreTrailingSlashIsFalse() {
+		this.contextRunner.withPropertyValues("management.metrics.web.server.request.ignore-trailing-slash=false")
+				.run((context) -> {
+					assertThat(context).hasSingleBean(DefaultWebFluxTagsProvider.class);
+					assertThat(ReflectionTestUtils.getField(context.getBean(DefaultWebFluxTagsProvider.class),
+							"ignoreTrailingSlash")).isEqualTo(false);
+				});
+	}
+
 	@Test
 	void shouldNotOverrideCustomTagsProvider() {
 		this.contextRunner.withUserConfiguration(CustomWebFluxTagsProviderConfig.class)

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/web/servlet/WebMvcMetricsAutoConfigurationTests.java

@@ -48,6 +48,7 @@ import org.springframework.boot.web.servlet.FilterRegistrationBean;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.Ordered;
+import org.springframework.test.util.ReflectionTestUtils;
 import org.springframework.test.web.servlet.MockMvc;
 import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
 import org.springframework.test.web.servlet.setup.MockMvcBuilders;
@@ -62,6 +63,7 @@ import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.
  * @author Andy Wilkinson
  * @author Dmytro Nosan
  * @author Tadaya Tsuyukubo
+ * @author Madhura Bhave
  */
 @ExtendWith(OutputCaptureExtension.class)
 class WebMvcMetricsAutoConfigurationTests {
@@ -79,12 +81,24 @@ class WebMvcMetricsAutoConfigurationTests {
 	void definesTagsProviderAndFilterWhenMeterRegistryIsPresent() {
 		this.contextRunner.run((context) -> {
 			assertThat(context).hasSingleBean(DefaultWebMvcTagsProvider.class);
+			assertThat(ReflectionTestUtils.getField(context.getBean(DefaultWebMvcTagsProvider.class),
+					"ignoreTrailingSlash")).isEqualTo(true);
 			assertThat(context).hasSingleBean(FilterRegistrationBean.class);
 			assertThat(context.getBean(FilterRegistrationBean.class).getFilter())
 					.isInstanceOf(WebMvcMetricsFilter.class);
 		});
 	}
 
+	@Test
+	void tagsProviderWhenIgnoreTrailingSlashIsFalse() {
+		this.contextRunner.withPropertyValues("management.metrics.web.server.request.ignore-trailing-slash=false")
+				.run((context) -> {
+					assertThat(context).hasSingleBean(DefaultWebMvcTagsProvider.class);
+					assertThat(ReflectionTestUtils.getField(context.getBean(DefaultWebMvcTagsProvider.class),
+							"ignoreTrailingSlash")).isEqualTo(false);
+				});
+	}
+
 	@Test
 	void tagsProviderBacksOff() {
 		this.contextRunner.withUserConfiguration(TagsProviderConfiguration.class).run((context) -> {

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/web/reactive/server/DefaultWebFluxTagsProvider.java

@@ -31,10 +31,20 @@ import org.springframework.web.server.ServerWebExchange;
  */
 public class DefaultWebFluxTagsProvider implements WebFluxTagsProvider {
 
+	private final boolean ignoreTrailingSlash;
+
+	public DefaultWebFluxTagsProvider() {
+		this(false);
+	}
+
+	public DefaultWebFluxTagsProvider(boolean ignoreTrailingSlash) {
+		this.ignoreTrailingSlash = ignoreTrailingSlash;
+	}
+
 	@Override
 	public Iterable<Tag> httpRequestTags(ServerWebExchange exchange, Throwable exception) {
-		return Arrays.asList(WebFluxTags.method(exchange), WebFluxTags.uri(exchange), WebFluxTags.exception(exception),
-				WebFluxTags.status(exchange), WebFluxTags.outcome(exchange));
+		return Arrays.asList(WebFluxTags.method(exchange), WebFluxTags.uri(exchange, this.ignoreTrailingSlash),
+				WebFluxTags.exception(exception), WebFluxTags.status(exchange), WebFluxTags.outcome(exchange));
 	}
 
 }

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/web/reactive/server/WebFluxTags.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.actuate.metrics.web.reactive.server;
 
+import java.util.regex.Pattern;
+
 import io.micrometer.core.instrument.Tag;
 
 import org.springframework.boot.actuate.metrics.http.Outcome;
@@ -48,6 +50,8 @@ public final class WebFluxTags {
 
 	private static final Tag EXCEPTION_NONE = Tag.of("exception", "None");
 
+	private static final Pattern TRAILING_SLASH_PATTERN = Pattern.compile("/$");
+
 	private WebFluxTags() {
 	}
 
@@ -87,9 +91,27 @@ public final class WebFluxTags {
 	 * @return the uri tag derived from the exchange
 	 */
 	public static Tag uri(ServerWebExchange exchange) {
+		return uri(exchange, false);
+	}
+
+	/**
+	 * Creates a {@code uri} tag based on the URI of the given {@code exchange}. Uses the
+	 * {@link HandlerMapping#BEST_MATCHING_PATTERN_ATTRIBUTE} best matching pattern if
+	 * available. Falling back to {@code REDIRECTION} for 3xx responses, {@code NOT_FOUND}
+	 * for 404 responses, {@code root} for requests with no path info, and {@code UNKNOWN}
+	 * for all other requests.
+	 * @param exchange the exchange
+	 * @param ignoreTrailingSlash whether to ignore the trailing slash
+	 * @return the uri tag derived from the exchange
+	 */
+	public static Tag uri(ServerWebExchange exchange, boolean ignoreTrailingSlash) {
 		PathPattern pathPattern = exchange.getAttribute(HandlerMapping.BEST_MATCHING_PATTERN_ATTRIBUTE);
 		if (pathPattern != null) {
-			return Tag.of("uri", pathPattern.getPatternString());
+			String patternString = pathPattern.getPatternString();
+			if (ignoreTrailingSlash) {
+				patternString = TRAILING_SLASH_PATTERN.matcher(patternString).replaceAll("");
+			}
+			return Tag.of("uri", patternString);
 		}
 		HttpStatus status = exchange.getResponse().getStatusCode();
 		if (status != null) {

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/web/servlet/DefaultWebMvcTagsProvider.java

@@ -30,16 +30,26 @@ import io.micrometer.core.instrument.Tags;
  */
 public class DefaultWebMvcTagsProvider implements WebMvcTagsProvider {
 
+	private final boolean ignoreTrailingSlash;
+
+	public DefaultWebMvcTagsProvider() {
+		this(false);
+	}
+
+	public DefaultWebMvcTagsProvider(boolean ignoreTrailingSlash) {
+		this.ignoreTrailingSlash = ignoreTrailingSlash;
+	}
+
 	@Override
 	public Iterable<Tag> getTags(HttpServletRequest request, HttpServletResponse response, Object handler,
 			Throwable exception) {
-		return Tags.of(WebMvcTags.method(request), WebMvcTags.uri(request, response), WebMvcTags.exception(exception),
-				WebMvcTags.status(response), WebMvcTags.outcome(response));
+		return Tags.of(WebMvcTags.method(request), WebMvcTags.uri(request, response, this.ignoreTrailingSlash),
+				WebMvcTags.exception(exception), WebMvcTags.status(response), WebMvcTags.outcome(response));
 	}
 
 	@Override
 	public Iterable<Tag> getLongRequestTags(HttpServletRequest request, Object handler) {
-		return Tags.of(WebMvcTags.method(request), WebMvcTags.uri(request, null));
+		return Tags.of(WebMvcTags.method(request), WebMvcTags.uri(request, null, this.ignoreTrailingSlash));
 	}
 
 }

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/web/servlet/WebMvcTags.java

@@ -94,9 +94,27 @@ public final class WebMvcTags {
 	 * @return the uri tag derived from the request
 	 */
 	public static Tag uri(HttpServletRequest request, HttpServletResponse response) {
+		return uri(request, response, false);
+	}
+
+	/**
+	 * Creates a {@code uri} tag based on the URI of the given {@code request}. Uses the
+	 * {@link HandlerMapping#BEST_MATCHING_PATTERN_ATTRIBUTE} best matching pattern if
+	 * available. Falling back to {@code REDIRECTION} for 3xx responses, {@code NOT_FOUND}
+	 * for 404 responses, {@code root} for requests with no path info, and {@code UNKNOWN}
+	 * for all other requests.
+	 * @param request the request
+	 * @param response the response
+	 * @param ignoreTrailingSlash whether to ignore the trailing slash
+	 * @return the uri tag derived from the request
+	 */
+	public static Tag uri(HttpServletRequest request, HttpServletResponse response, boolean ignoreTrailingSlash) {
 		if (request != null) {
 			String pattern = getMatchingPattern(request);
 			if (pattern != null) {
+				if (ignoreTrailingSlash) {
+					pattern = TRAILING_SLASH_PATTERN.matcher(pattern).replaceAll("");
+				}
 				return Tag.of("uri", pattern);
 			}
 			if (response != null) {

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/metrics/web/reactive/server/MetricsWebFilterTests.java

@@ -37,6 +37,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  * Tests for {@link MetricsWebFilter}
  *
  * @author Brian Clozel
+ * @author Madhura Bhave
  */
 class MetricsWebFilterTests {
 
@@ -50,7 +51,7 @@ class MetricsWebFilterTests {
 	void setup() {
 		MockClock clock = new MockClock();
 		this.registry = new SimpleMeterRegistry(SimpleConfig.DEFAULT, clock);
-		this.webFilter = new MetricsWebFilter(this.registry, new DefaultWebFluxTagsProvider(), REQUEST_METRICS_NAME,
+		this.webFilter = new MetricsWebFilter(this.registry, new DefaultWebFluxTagsProvider(true), REQUEST_METRICS_NAME,
 				AutoTimer.ENABLED);
 	}
 
@@ -102,6 +103,19 @@ class MetricsWebFilterTests {
 		assertMetricsContainsTag("status", "500");
 	}
 
+	@Test
+	void trailingSlashShouldNotRecordDuplicateMetrics() {
+		MockServerWebExchange exchange1 = createExchange("/projects/spring-boot", "/projects/{project}");
+		MockServerWebExchange exchange2 = createExchange("/projects/spring-boot", "/projects/{project}/");
+		this.webFilter.filter(exchange1, (serverWebExchange) -> exchange1.getResponse().setComplete())
+				.block(Duration.ofSeconds(30));
+		this.webFilter.filter(exchange2, (serverWebExchange) -> exchange2.getResponse().setComplete())
+				.block(Duration.ofSeconds(30));
+		assertThat(this.registry.get(REQUEST_METRICS_NAME).tag("uri", "/projects/{project}").timer().count())
+				.isEqualTo(2);
+		assertThat(this.registry.get(REQUEST_METRICS_NAME).tag("status", "200").timer().count()).isEqualTo(2);
+	}
+
 	private MockServerWebExchange createExchange(String path, String pathPattern) {
 		PathPatternParser parser = new PathPatternParser();
 		MockServerWebExchange exchange = MockServerWebExchange.from(MockServerHttpRequest.get(path).build());

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/metrics/web/servlet/WebMvcMetricsFilterTests.java

@@ -289,6 +289,14 @@ class WebMvcMetricsFilterTests {
 		assertThat(this.prometheusRegistry.scrape()).contains("le=\"30.0\"");
 	}
 
+	@Test
+	void trailingSlashShouldNotRecordDuplicateMetrics() throws Exception {
+		this.mvc.perform(get("/api/c1/simple/10")).andExpect(status().isOk());
+		this.mvc.perform(get("/api/c1/simple/10/")).andExpect(status().isOk());
+		assertThat(this.registry.get("http.server.requests").tags("status", "200", "uri", "/api/c1/simple/{id}").timer()
+				.count()).isEqualTo(2);
+	}
+
 	@Target({ ElementType.METHOD })
 	@Retention(RetentionPolicy.RUNTIME)
 	@Timed(percentiles = 0.95)
@@ -356,7 +364,7 @@ class WebMvcMetricsFilterTests {
 
 		@Bean
 		WebMvcMetricsFilter webMetricsFilter(MeterRegistry registry, WebApplicationContext ctx) {
-			return new WebMvcMetricsFilter(registry, new DefaultWebMvcTagsProvider(), "http.server.requests",
+			return new WebMvcMetricsFilter(registry, new DefaultWebMvcTagsProvider(true), "http.server.requests",
 					AutoTimer.ENABLED);
 		}
 
@@ -380,6 +388,11 @@ class WebMvcMetricsFilterTests {
 			return id.toString();
 		}
 
+		@GetMapping("/simple/{id}")
+		String simpleMapping(@PathVariable Long id) {
+			return id.toString();
+		}
+
 		@Timed
 		@Timed(value = "my.long.request", extraTags = { "region", "test" }, longTask = true)
 		@GetMapping("/callable/{id}")