The basic relationships among POD, containers and services are as follows.
Example) Deployment with Pgpool-II
In this deployment scenario, Pgpool-II is used to provide connection pooling and load balancing. End user application will point its connection to Pgpool service. Depending on the transaction type, Pgpool will forward the connection to either the Master Pod or the Replica Pod. If a failover/switchover occurs, the FEP pgpool2 will direct traffic to the new FEP master Pod. This is transparent to the end user application.
Example) Deployment without Pgpool-II
Users can also run applications such as SQL directly against the FEPCluster without configuring Pgpool-II. In this deployment scenario, end user application will point its connection to the FEP master service. If a failover/switchover occurs, the FEP master service will point to the new FEP master Pod automatically. The end user application will experience a disconnection. When it re-establishes the connection, it will be connected to the new FEP master Pod. There is no need to reconfigure the application connection string.
