3 files changed, 117 insertions, 0 deletions
diff --git a/common/src/main/java/org/onap/so/db/connections/DbDnsIpAddress.java b/common/src/main/java/org/onap/so/db/connections/DbDnsIpAddress.java
new file mode 100644
index 0000000000..8ee63a487b
--- /dev/null
+++ b/common/src/main/java/org/onap/so/db/connections/DbDnsIpAddress.java
@@ -0,0 +1,20 @@
+package org.onap.so.db.connections;
+
+import org.springframework.context.annotation.Scope;
+import org.springframework.stereotype.Component;
+
+@Component
+@Scope("singleton")
+public class DbDnsIpAddress {
+
+    private String ipAddress;
+
+    public String getIpAddress() {
+        return ipAddress;
+    }
+
+    public void setIpAddress(String ipAddress) {
+        this.ipAddress = ipAddress;
+    }
+
+}
diff --git a/common/src/main/java/org/onap/so/db/connections/ScheduledDnsLookup.java b/common/src/main/java/org/onap/so/db/connections/ScheduledDnsLookup.java
new file mode 100644
index 0000000000..14f2f5e9b7
--- /dev/null
+++ b/common/src/main/java/org/onap/so/db/connections/ScheduledDnsLookup.java
@@ -0,0 +1,78 @@
+package org.onap.so.db.connections;
+
+import java.lang.management.ManagementFactory;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.util.Set;
+import javax.management.JMX;
+import javax.management.MBeanServer;
+import javax.management.ObjectInstance;
+import javax.management.ObjectName;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Profile;
+import org.springframework.scheduling.annotation.Scheduled;
+import org.springframework.stereotype.Component;
+import com.zaxxer.hikari.HikariPoolMXBean;
+
+@Component
+@Profile("!test")
+public class ScheduledDnsLookup {
+
+    private static final String JMX_HIKARI_DB_POOL_LOOKUP = "com.zaxxer.hikari:type=Pool (*,*";
+
+    private static final String DB_HOST = "DB_HOST";
+
+    @Autowired
+    private DbDnsIpAddress dnsIpAddress;
+
+    private static Logger logger = LoggerFactory.getLogger(ScheduledDnsLookup.class);
+
+    @Scheduled(fixedRate = 15000)
+    public void performDnsLookup() {
+
+        String dnsUrl = System.getenv(DB_HOST);
+
+        try {
+            if (dnsUrl == null) {
+                logger.error("Database DNS is not provided. Please verify the configuration");
+                return;
+            }
+
+            InetAddress inetAddress = java.net.InetAddress.getByName(dnsUrl);
+            String ipAddress = inetAddress.getHostAddress();
+            String currentIpAddress = dnsIpAddress.getIpAddress();
+            /* This is in initial state */
+            if (currentIpAddress == null) {
+                dnsIpAddress.setIpAddress(ipAddress);
+                return;
+            }
+
+            if ((ipAddress != null) && (!ipAddress.equalsIgnoreCase(currentIpAddress))) {
+                logger.debug("Switched Database IP Address from {} to {}", currentIpAddress, ipAddress);
+                softEvictConnectionPool();
+                dnsIpAddress.setIpAddress(ipAddress);
+            }
+        } catch (UnknownHostException e) {
+            logger.warn("Database DNS %s is not resolvable to an IP Address", dnsUrl);
+        }
+
+    }
+
+    private void softEvictConnectionPool() {
+        try {
+            MBeanServer mBeanServer = ManagementFactory.getPlatformMBeanServer();
+            ObjectName queryObj = new ObjectName(JMX_HIKARI_DB_POOL_LOOKUP);
+            Set<ObjectInstance> objects = mBeanServer.queryMBeans(queryObj, null);
+            for (ObjectInstance objectInstance : objects) {
+                ObjectName poolObject = objectInstance.getObjectName();
+                HikariPoolMXBean poolProxy = JMX.newMXBeanProxy(mBeanServer, poolObject, HikariPoolMXBean.class);
+                logger.debug("database connection pool is soft evicted for connections");
+                poolProxy.softEvictConnections();
+            }
+        } catch (Exception e) {
+            logger.warn("Error encountered in evicting DB connection pool", e);
+        }
+    }
+}
diff --git a/common/src/test/java/org/onap/so/db/connections/DbDnsIpAddressTest.java b/common/src/test/java/org/onap/so/db/connections/DbDnsIpAddressTest.java
new file mode 100644
index 0000000000..0dc35a054c
--- /dev/null
+++ b/common/src/test/java/org/onap/so/db/connections/DbDnsIpAddressTest.java
@@ -0,0 +1,19 @@
+package org.onap.so.db.connections;
+
+import static org.junit.Assert.assertEquals;
+import org.junit.Test;
+
+public class DbDnsIpAddressTest {
+
+    @Test
+    public void test() {
+        final String expectedIpAddress = "10.0.75.1";
+
+        DbDnsIpAddress dbDnsIpAddress = new DbDnsIpAddress();
+        dbDnsIpAddress.setIpAddress(expectedIpAddress);
+
+        assertEquals(expectedIpAddress, dbDnsIpAddress.getIpAddress());
+
+    }
+
+}