Blitz some more special characters from the metric names

When MVC path matchers are used as metric keys, they can still contain
invalid characters and patterns (like asterisks). This change removes
some more special characters and also tidies up the names a bit so
no key part starts or ends with "-" (which is ugly).

Fixes gh-1528

Author: Dave Syer

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/autoconfigure/MetricFilterAutoConfiguration.java

@@ -101,7 +101,7 @@ protected void doFilterInternal(HttpServletRequest request,
 					// not convertible
 				}
 				if (bestMatchingPattern != null) {
-					suffix = bestMatchingPattern.toString().replaceAll("[{}]", "-");
+					suffix = fixSpecialCharacters(bestMatchingPattern.toString());
 				}
 				else if (httpStatus.is4xxClientError()) {
 					suffix = UNKNOWN_PATH_SUFFIX;
@@ -114,6 +114,20 @@ else if (httpStatus.is4xxClientError()) {
 			}
 		}
 
+		private String fixSpecialCharacters(String value) {
+			String result = value.replaceAll("[{}]", "-");
+			result = result.replace("**", "-star-star-");
+			result = result.replace("*", "-star-");
+			result = result.replace("/-", "/");
+			if (result.endsWith("-")) {
+				result = result.substring(0, result.length() - 1);
+			}
+			if (result.startsWith("-")) {
+				result = result.substring(1);
+			}
+			return result;
+		}
+
 		private int getStatus(HttpServletResponse response) {
 			try {
 				return response.getStatus();

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/autoconfigure/MetricFilterAutoConfigurationTests.java

@@ -89,9 +89,9 @@ public void recordsHttpInteractionsWithTemplateVariable() throws Exception {
 		mvc.perform(get("/templateVarTest/foo")).andExpect(status().isOk());
 
 		verify(context.getBean(CounterService.class)).increment(
-				"status.200.templateVarTest.-someVariable-");
+				"status.200.templateVarTest.someVariable");
 		verify(context.getBean(GaugeService.class)).submit(
-				eq("response.templateVarTest.-someVariable-"), anyDouble());
+				eq("response.templateVarTest.someVariable"), anyDouble());
 		context.close();
 	}
 
@@ -106,9 +106,9 @@ public void recordsKnown404HttpInteractionsAsSingleMetricWithPathAndTemplateVari
 		mvc.perform(get("/knownPath/foo")).andExpect(status().isNotFound());
 
 		verify(context.getBean(CounterService.class)).increment(
-				"status.404.knownPath.-someVariable-");
+				"status.404.knownPath.someVariable");
 		verify(context.getBean(GaugeService.class)).submit(
-				eq("response.knownPath.-someVariable-"), anyDouble());
+				eq("response.knownPath.someVariable"), anyDouble());
 		context.close();
 	}