-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 David,
On 8/24/16 5:22 PM, David Day wrote: > Apache Tomcat/7.0.54 CentOS release 6.7 AWS RDS Aurora 5.6.10a > > Using RDS in a failover configuration, AWS directs requests to the > write instance with a cluster CNAME e.g. > dbname-cluster.cluster-id.us-west-2.rds.amazonaws.com, and the > read-only instance to it's canonical name e.g. > dbname-us-west-2c.id.us-west-2.rds.amazonaws.com. Connections are > established to the IP address of the writer. After a failover the > original writer and reader instances change roles, but the > application continues to send traffic to the original writer, which > now has become read-only. This results in errors and requires > Tomcat to be restarted. > > A confirmed fix is to disable DNS cache by setting > networkaddress.cache.ttl=0 in > $JAVA_HOME/jre/lib/security/java.security. A downside is the loss > of DNS cache for other network calls from the application. I'm > looking for a method to periodically test the state of the > database, and if determined to be read-only, create new > connections. By that time, failover will have completed and new > requests to the CNAME will then result to the writer instance. > > I've read some on jdbcInterceptors and connection state, but > nothing strikes me as a method to test the database is read-only > then take action. I'd like help if you know of connection settings > I can try, or feedback if disabling DNS cache seems a reasonable > solution. How, in general, would you test to see if the database is in read-only mode? - -chris -----BEGIN PGP SIGNATURE----- Comment: GPGTools - http://gpgtools.org Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBCAAGBQJXv0iLAAoJEBzwKT+lPKRYQ2MQAKDZ4x0h+qSh7G6SmXhk20Wh +DETPSVrI6ENHwkJIik+qImEZbpQmkvTM34hIz5t6wPOmqlLSI60alLNNZ2w5dd4 dloUQAuFkkOyEc61ELCmo0+ZscEdDTlaStXIvh9kP/nglobdc5D2qEwW21274tNq bE1mFZCa4rllxwdGRFdjev9m20ekzS1x8K+IOHekGELPWcoDf4ka6+C1H1bfIkxt VNWQCQ6ALE60/q4RFeRyFII0eu4glR6YryF2QAZFt2ZYbgBzQM7ENH0Z1O1+fdYa QYevdyguPeeVgxoxVzelLGDn+OEZanH4va3TyXWPa6lT//gvPNph+vZGIO9+Y+eF vpZs6LX39ILY5toLpmi5qz+ZL6Q0TsOPOKetDqItuMbPp50tqGYmag/qVdHidnqR ynIeha1aTUxkKeAlujjYtcYKraJoc7ESxeDfISuNhT3Lo7TlztLZgDBOlcCGHWSK b0jMpto7cjsk9JvaKwz5tI6TBsiDCC0s6c7R7i130pm54jX0vMCukzTSD78Z4ClS PyTwaXNUZvjIWcTWPpSToiB9gqsrn1Zw1D/SeDGczvFNqR4fucPnMounUf4Luru0 QdfQ5vYxFf2ePwohXmpScu3z5D7B9NQDkuGecxVNlOx1wX84xxJdzFWkzU71cgdd R/6N+ZiugFroPNIt20/0 =/FXe -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
