Don't fail redis rule if redis is already running.

spring-cloud-gateway-core/src/test/java/org/springframework/cloud/gateway/test/support/redis/RedisRule.java

@@ -1,20 +1,31 @@
 package org.springframework.cloud.gateway.test.support.redis;
 
+import java.io.IOException;
+import java.net.ServerSocket;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.junit.rules.ExternalResource;
+import redis.embedded.RedisServer;
+
 import static java.lang.String.format;
 import static java.util.stream.IntStream.range;
 
-import java.io.IOException;
-import java.net.ServerSocket;
-import org.junit.rules.ExternalResource;
-import redis.embedded.RedisServer;
-
 public class RedisRule extends ExternalResource {
 
-	public static RedisRule bindToPort(final int port) {
+	private Log log = LogFactory.getLog(getClass());
+
+	public static final int DEFAULT_REDIS_PORT = 6379;
+
+	public static RedisRule bindToDefaultPort() {
+		return new RedisRule(DEFAULT_REDIS_PORT, true);
+	}
+
+	public static RedisRule bindToDefaultPort(int port) {
 		return new RedisRule(port);
 	}
 
-	public static RedisRule bindToFirstOpenPort(final int startInclusive, final int endExclusive) {
+	public static RedisRule bindToFirstOpenPort(int startInclusive, int endExclusive) {
 		return new RedisRule(findOpenPort(startInclusive, endExclusive));
 	}
 
@@ -36,11 +47,17 @@ public class RedisRule extends ExternalResource {
 	}
 
 	private final int port;
+	private final boolean ignoreDefaultPortFailure;
 
 	private RedisServer redisServer;
 
-	private RedisRule(final int port) {
+	private RedisRule(int port) {
+		this(port, false);
+	}
+
+	private RedisRule(int port, boolean ignoreDefaultPortFailure) {
 		this.port = port;
+		this.ignoreDefaultPortFailure = ignoreDefaultPortFailure;
 	}
 
 	@Override
@@ -49,8 +66,12 @@ public class RedisRule extends ExternalResource {
 			redisServer = RedisServer.builder().port(port).setting("maxmemory 16MB").build();
 			redisServer.start();
 		} catch (final Exception e) {
-			throw new RuntimeException(format("Error while initializing the Redis server"
-					+ " on port %d", port), e);
+			if (port == DEFAULT_REDIS_PORT && ignoreDefaultPortFailure) {
+				log.info("Unable to start embedded Redis on default port. Ignoring error. Assuming redis is already running.");
+			} else {
+				throw new RuntimeException(format("Error while initializing the Redis server"
+						+ " on port %d", port), e);
+			}
 		}
 	}