Support more lenient DB2 product lookups

Update DataSourceHealthIndicator to support pattern based matching for
DB2 products. Prior to this commit product identifiers of the form
`DB2/LINUXX8664` were not supported.

Fixes gh-3377

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/DataSourceHealthIndicator.java

@@ -20,10 +20,7 @@ import java.sql.Connection;
 import java.sql.ResultSet;
 import java.sql.ResultSetMetaData;
 import java.sql.SQLException;
-import java.util.Collections;
-import java.util.HashMap;
 import java.util.List;
-import java.util.Map;
 
 import javax.sql.DataSource;
 
@@ -51,18 +48,6 @@ import org.springframework.util.StringUtils;
 public class DataSourceHealthIndicator extends AbstractHealthIndicator implements
 		InitializingBean {
 
-	private static final Map<String, String> PRODUCT_SPECIFIC_QUERIES;
-	static {
-		Map<String, String> queries = new HashMap<String, String>();
-		queries.put("HSQL Database Engine", "SELECT COUNT(*) FROM "
-				+ "INFORMATION_SCHEMA.SYSTEM_USERS");
-		queries.put("Oracle", "SELECT 'Hello' from DUAL");
-		queries.put("Apache Derby", "SELECT 1 FROM SYSIBM.SYSDUMMY1");
-		queries.put("DB2", "SELECT 1 FROM SYSIBM.SYSDUMMY1");
-		queries.put("Informix Dynamic Server", "select count(*) from systables");
-		PRODUCT_SPECIFIC_QUERIES = Collections.unmodifiableMap(queries);
-	}
-
 	private static final String DEFAULT_QUERY = "SELECT 1";
 
 	private DataSource dataSource;
@@ -145,7 +130,10 @@ public class DataSourceHealthIndicator extends AbstractHealthIndicator implement
 	protected String getValidationQuery(String product) {
 		String query = this.query;
 		if (!StringUtils.hasText(query)) {
-			query = PRODUCT_SPECIFIC_QUERIES.get(product);
+			Product specific = Product.forProduct(product);
+			if (specific != null) {
+				query = specific.getQuery();
+			}
 		}
 		if (!StringUtils.hasText(query)) {
 			query = DEFAULT_QUERY;
@@ -196,4 +184,53 @@ public class DataSourceHealthIndicator extends AbstractHealthIndicator implement
 
 	}
 
+	protected static enum Product {
+
+		HSQLDB("HSQL Database Engine",
+				"SELECT COUNT(*) FROM INFORMATION_SCHEMA.SYSTEM_USERS"),
+
+		ORACLE("Oracle", "SELECT 'Hello' from DUAL"),
+
+		DERBY("Apache Derby", "SELECT 1 FROM SYSIBM.SYSDUMMY1"),
+
+		DB2("DB2", "SELECT 1 FROM SYSIBM.SYSDUMMY1") {
+
+			@Override
+			protected boolean matchesProduct(String product) {
+				return super.matchesProduct(product)
+						|| product.toLowerCase().startsWith("db2/");
+			}
+
+		},
+
+		INFORMIX("Informix Dynamic Server", "select count(*) from systables");
+
+		private final String product;
+
+		private final String query;
+
+		private Product(String product, String query) {
+			this.product = product;
+			this.query = query;
+		}
+
+		protected boolean matchesProduct(String product) {
+			return this.product.equalsIgnoreCase(product);
+		}
+
+		public String getQuery() {
+			return this.query;
+		}
+
+		public static Product forProduct(String product) {
+			for (Product candidate : values()) {
+				if (candidate.matchesProduct(product)) {
+					return candidate;
+				}
+			}
+			return null;
+		}
+
+	}
+
 }

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/health/DataSourceHealthIndicatorTests.java

@@ -22,12 +22,15 @@ import javax.sql.DataSource;
 
 import org.junit.Before;
 import org.junit.Test;
+import org.springframework.boot.actuate.health.DataSourceHealthIndicator.Product;
 import org.springframework.boot.autoconfigure.jdbc.EmbeddedDatabaseConnection;
 import org.springframework.jdbc.core.JdbcTemplate;
 import org.springframework.jdbc.datasource.DriverManagerDataSource;
 import org.springframework.jdbc.datasource.SingleConnectionDataSource;
 
+import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.notNullValue;
+import static org.hamcrest.Matchers.nullValue;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertThat;
@@ -97,4 +100,16 @@ public class DataSourceHealthIndicatorTests {
 		verify(connection, times(2)).close();
 	}
 
+	@Test
+	public void productLooksups() throws Exception {
+		assertThat(Product.forProduct("newone"), nullValue());
+		assertThat(Product.forProduct("HSQL Database Engine"), equalTo(Product.HSQLDB));
+		assertThat(Product.forProduct("Oracle"), equalTo(Product.ORACLE));
+		assertThat(Product.forProduct("Apache Derby"), equalTo(Product.DERBY));
+		assertThat(Product.forProduct("DB2"), equalTo(Product.DB2));
+		assertThat(Product.forProduct("DB2/LINUXX8664"), equalTo(Product.DB2));
+		assertThat(Product.forProduct("Informix Dynamic Server"),
+				equalTo(Product.INFORMIX));
+	}
+
 }