SSL Error pool_ssl: "SSL_read": "unexpected eof while reading" when using Pgpool2

[yukha-dw]

Hello, I am trying to use Pgpool as load balancer between Kong and PostgreSQL. But there's SSL error log on Pgpool node everytime Kong sends this query:

SELECT "id", EXTRACT(EPOCH FROM "last_seen" AT TIME ZONE 'UTC') AS "last_seen", EXTRACT(EPOCH FROM "updated_at" AT TIME ZONE 'UTC') AS "updated_at", "ip", "config_hash", "hostname", "version", "sync_status", "labels", "cert_details", "rpc_capabilities",FLOOR(EXTRACT(EPOCH FROM ("ttl" AT TIME ZONE 'UTC' - CURRENT_TIMESTAMP AT TIME ZONE 'UTC'))) AS "ttl"
	    FROM "clustering_data_planes"
	   WHERE ("ttl" IS NULL OR "ttl" >= CURRENT_TIMESTAMP AT TIME ZONE 'UTC')
	ORDER BY "id"
	   LIMIT 1001;"

Pgpool Logs:

2024-12-18 07:46:23.752: kong pid 305: user: kong : DEBUG:  session context: unsetting query in progress. DONE
2024-12-18 07:46:23.752: kong pid 305: user: kong : LOCATION:  pool_session_context.c:260
2024-12-18 07:46:23.752: kong pid 305: user: kong : DEBUG:  pool_query_context_destroy: query context:0x5d073b2dc418 query: "  SELECT "id", EXTRACT(EPOCH FROM "last_seen" AT TIME ZONE 'UTC') AS "last_seen", EXTRACT(EPOCH FROM "updated_at" AT TIME ZONE 'UTC') AS "updated_at", "ip", "config_hash", "hostname", "version", "sync_status", "labels", "cert_details", "rpc_capabilities",FLOOR(EXTRACT(EPOCH FROM ("ttl" AT TIME ZONE 'UTC' - CURRENT_TIMESTAMP AT TIME ZONE 'UTC'))) AS "ttl"
	    FROM "clustering_data_planes"
	   WHERE ("ttl" IS NULL OR "ttl" >= CURRENT_TIMESTAMP AT TIME ZONE 'UTC')
	ORDER BY "id"
	   LIMIT 1001;"
2024-12-18 07:46:23.752: kong pid 305: user: kong : LOCATION:  pool_query_context.c:109
2024-12-18 07:46:23.752: kong pid 305: user: kong : DEBUG:  session context: unsetting query in progress. DONE
2024-12-18 07:46:23.752: kong pid 305: user: kong : LOCATION:  pool_session_context.c:260
2024-12-18 07:46:23.754: kong pid 305: user: kong : LOG:  pool_ssl: "SSL_read": "unexpected eof while reading"
2024-12-18 07:46:23.754: kong pid 305: user: kong : LOCATION:  pool_ssl.c:445
2024-12-18 07:46:23.754: kong pid 305: user: kong : DEBUG:  unable to read data from frontend
2024-12-18 07:46:23.754: kong pid 305: user: kong : DETAIL:  socket read failed with error "Success"
2024-12-18 07:46:23.754: kong pid 305: user: kong : LOCATION:  pool_stream.c:259
2024-12-18 07:46:23.754: kong pid 305: user: kong : DEBUG:  connection_count_down: number of connected children: 0
2024-12-18 07:46:23.754: kong pid 305: user: kong : LOCATION:  child.c:1429
2024-12-18 07:46:23.755: kong pid 305: user: kong : LOG:  frontend disconnection: session time: 0:00:00.068 user=kong database=kong host=10.101.14.10 port=33322
2024-12-18 07:46:23.755: kong pid 305: user: kong : LOCATION:  child.c:2149
2024-12-18 07:46:23.755: kong pid 305: user: kong : DEBUG:  session context: unsetting query in progress. DONE
2024-12-18 07:46:23.755: kong pid 305: user: kong : LOCATION:  pool_session_context.c:260
2024-12-18 07:46:23.755: kong pid 305: user: kong : DEBUG:  pool_write: to backend: 0 kind:X
2024-12-18 07:46:23.755: kong pid 305: user: kong : LOCATION:  pool_stream.c:467
2024-12-18 07:46:23.755: kong pid 305: user: kong : DEBUG:  pool_flush_it: flush size: 5
2024-12-18 07:46:23.755: kong pid 305: user: kong : LOCATION:  pool_stream.c:650
2024-12-18 07:46:23.755: kong pid 305: user: kong : DEBUG:  pool_write: to backend: 1 kind:X
2024-12-18 07:46:23.755: kong pid 305: user: kong : LOCATION:  pool_stream.c:467
2024-12-18 07:46:23.755: kong pid 305: user: kong : DEBUG:  pool_flush_it: flush size: 5
2024-12-18 07:46:23.755: kong pid 305: user: kong : LOCATION:  pool_stream.c:650
2024-12-18 07:46:23.755: kong pid 305: user: kong : DEBUG:  pool_write: to backend: 2 kind:X
2024-12-18 07:46:23.755: kong pid 305: user: kong : LOCATION:  pool_stream.c:467
2024-12-18 07:46:23.755: kong pid 305: user: kong : DEBUG:  pool_flush_it: flush size: 5
2024-12-18 07:46:23.755: kong pid 305: user: kong : LOCATION:  pool_stream.c:650
2024-12-18 07:46:23.755: kong pid 305: user: kong : DEBUG:  RESET ALL CONFIG VARIABLES
2024-12-18 07:46:23.755: kong pid 305: user: kong : LOCATION:  pool_config_variables.c:5918

There is no error on Kong and PostgreSQL side. Based on https://www.pgpool.net/pipermail/pgpool-general/2021-December/000629.html, this might be caused by pgmoon does not properly closes the connection between Kong and Pgpool.

Can I ignore this issue? Thank you in advance!

[Oyami-Srk]

As long as the database is up to date, there is no need to worry about unexpected EOF. Is there any influence on data integrity?

[yukha-dw]

Is there any influence on data integrity?

I don't think so. Kong seems working just fine. But, because the issue is so persistent on this specific statement, I am afraid there's an edge case.