Improve handling of non-standard status codes in RestTemplate metrics

See gh-17991

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/web/client/RestTemplateExchangeTags.java

@@ -18,6 +18,9 @@ package org.springframework.boot.actuate.metrics.web.client;
 
 import java.io.IOException;
 import java.net.URI;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
 import java.util.regex.Pattern;
 
 import io.micrometer.core.instrument.Tag;
@@ -54,6 +57,18 @@ public final class RestTemplateExchangeTags {
 
 	private static final Tag OUTCOME_SERVER_ERROR = Tag.of("outcome", "SERVER_ERROR");
 
+	private static final Map<HttpStatus.Series, Tag> SERIES_OUTCOMES;
+
+	static {
+		Map<HttpStatus.Series, Tag> seriesOutcomes = new HashMap<>();
+		seriesOutcomes.put(HttpStatus.Series.INFORMATIONAL, OUTCOME_INFORMATIONAL);
+		seriesOutcomes.put(HttpStatus.Series.SUCCESSFUL, OUTCOME_SUCCESS);
+		seriesOutcomes.put(HttpStatus.Series.REDIRECTION, OUTCOME_REDIRECTION);
+		seriesOutcomes.put(HttpStatus.Series.CLIENT_ERROR, OUTCOME_CLIENT_ERROR);
+		seriesOutcomes.put(HttpStatus.Series.SERVER_ERROR, OUTCOME_SERVER_ERROR);
+		SERIES_OUTCOMES = Collections.unmodifiableMap(seriesOutcomes);
+	}
+
 	private RestTemplateExchangeTags() {
 	}
 
@@ -132,7 +147,7 @@ public final class RestTemplateExchangeTags {
 
 	/**
 	 * Creates an {@code outcome} {@code Tag} derived from the
-	 * {@link ClientHttpResponse#getStatusCode() status} of the given {@code response}.
+	 * {@link ClientHttpResponse#getRawStatusCode() status} of the given {@code response}.
 	 * @param response the response
 	 * @return the outcome tag
 	 * @since 2.2.0
@@ -140,28 +155,16 @@ public final class RestTemplateExchangeTags {
 	public static Tag outcome(ClientHttpResponse response) {
 		try {
 			if (response != null) {
-				HttpStatus statusCode = response.getStatusCode();
-				if (statusCode.is1xxInformational()) {
-					return OUTCOME_INFORMATIONAL;
-				}
-				if (statusCode.is2xxSuccessful()) {
-					return OUTCOME_SUCCESS;
-				}
-				if (statusCode.is3xxRedirection()) {
-					return OUTCOME_REDIRECTION;
+				HttpStatus.Series series = HttpStatus.Series.resolve(response.getRawStatusCode());
+				if (series != null) {
+					return SERIES_OUTCOMES.getOrDefault(series, OUTCOME_UNKNOWN);
 				}
-				if (statusCode.is4xxClientError()) {
-					return OUTCOME_CLIENT_ERROR;
 			}
-				if (statusCode.is5xxServerError()) {
-					return OUTCOME_SERVER_ERROR;
-				}
-			}
-			return OUTCOME_UNKNOWN;
 		}
 		catch (IOException | IllegalArgumentException ex) {
-			return OUTCOME_UNKNOWN;
+			// Continue
 		}
+		return OUTCOME_UNKNOWN;
 	}
 
 }

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

@@ -140,7 +140,7 @@ public final class WebClientExchangeTags {
 
 	/**
 	 * Creates an {@code outcome} {@code Tag} derived from the
-	 * {@link ClientResponse#statusCode() status} of the given {@code response}.
+	 * {@link ClientResponse#rawStatusCode() status} of the given {@code response}.
 	 * @param response the response
 	 * @return the outcome tag
 	 * @since 2.2.0
@@ -154,7 +154,7 @@ public final class WebClientExchangeTags {
 				}
 			}
 		}
-		catch (IllegalArgumentException exc) {
+		catch (IllegalArgumentException ex) {
 			// Continue
 		}
 		return OUTCOME_UNKNOWN;

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/metrics/web/client/RestTemplateExchangeTagsTests.java

@@ -81,7 +81,7 @@ class RestTemplateExchangeTagsTests {
 	@Test
 	void outcomeTagIsUnknownWhenResponseThrowsIOException() throws Exception {
 		ClientHttpResponse response = mock(ClientHttpResponse.class);
-		given(response.getStatusCode()).willThrow(IOException.class);
+		given(response.getRawStatusCode()).willThrow(IOException.class);
 		Tag tag = RestTemplateExchangeTags.outcome(response);
 		assertThat(tag.getValue()).isEqualTo("UNKNOWN");
 	}
@@ -89,7 +89,23 @@ class RestTemplateExchangeTagsTests {
 	@Test
 	void outcomeTagIsUnknownForCustomResponseStatus() throws Exception {
 		ClientHttpResponse response = mock(ClientHttpResponse.class);
-		given(response.getStatusCode()).willThrow(IllegalArgumentException.class);
+		given(response.getRawStatusCode()).willThrow(IllegalArgumentException.class);
+		Tag tag = RestTemplateExchangeTags.outcome(response);
+		assertThat(tag.getValue()).isEqualTo("UNKNOWN");
+	}
+
+	@Test
+	void outcomeTagIsClientErrorWhenResponseIsNonStandardInKnownSeries() throws IOException {
+		ClientHttpResponse response = mock(ClientHttpResponse.class);
+		given(response.getRawStatusCode()).willReturn(490);
+		Tag tag = RestTemplateExchangeTags.outcome(response);
+		assertThat(tag.getValue()).isEqualTo("CLIENT_ERROR");
+	}
+
+	@Test
+	void outcomeTagIsUnknownWhenResponseStatusIsInUnknownSeries() throws IOException {
+		ClientHttpResponse response = mock(ClientHttpResponse.class);
+		given(response.getRawStatusCode()).willReturn(701);
 		Tag tag = RestTemplateExchangeTags.outcome(response);
 		assertThat(tag.getValue()).isEqualTo("UNKNOWN");
 	}

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

@@ -148,7 +148,7 @@ class WebClientExchangeTagsTests {
 	}
 
 	@Test
-	void outcomeTagIsServerErrorWhenResponseIsNonStandardInKnownSeries() {
+	void outcomeTagIsClientErrorWhenResponseIsNonStandardInKnownSeries() {
 		given(this.response.rawStatusCode()).willReturn(490);
 		Tag tag = WebClientExchangeTags.outcome(this.response);
 		assertThat(tag.getValue()).isEqualTo("CLIENT_ERROR");