pg_createsubscriber currently outputs all messages (internal validation messages, standby server start/stop logs, recovery progress output, and output from utilities) directly to the console. As a result, users may find debugging and handling errors difficult. It would be more convenient if messages were separated and stored in different log files. There is already a similar implementation in pg_upgrade.
Proposed Solution:
Based on issues mentioned previously, I would like to propose a new argument -l <logdir> which can be specified for pg_createsubscriber. Using it would create the following log files:
logdir/pg_createsubscriber_server.log which captures all logs related to starting and stopping the standby server.
logdir/pg_createsubscriber_resetwal.log which captures the output of pg_resetwal
logdir/pg_createsubscriber_internal.log which captures internal diagnostic output from pg_createsubscriber (validations, checks, etc.)
Overall, this proposed solution could make the pg_createsubscriber command output messages more organized. The command would be easier to use as users will only have to read individual log files rather than parse through lots of possibly irrelevant output messages. I have attached the patch for this change.
Special thanks to Vignesh C. for his offlist guidance on this project.
