It tries to establish a connection to the database instance and if the connection request is progressing, it will be considered as a successful check and there is no provision to check the current role (Primary or Standby). So the question remains: Is the HAProxy’s built-in pgsql-check...
LibPQWalReceiverConnect Waiting in WAL receiver to establish connection to remote server. LibPQWalReceiverReceive Waiting in WAL receiver to receive data from remote server. SSLOpenServer Waiting for SSL while attempting connection. WalSenderWaitForWAL Waiting for WAL to be flushed...