database must exist to run exporter with specific user

[grumpyp]

We run postgres_exporter using the helm-chart on version 4.4.3

We created a designated postgres user for it and gave it the role pgmonitor. Once everything was setup we had the following errors.

2023-05-23 12:34:08.136 | ts=2023-05-23T10:34:08.135Z caller=collector.go:196 level=error msg="collector failed" name=bgwriter duration_seconds=0.008667515 err="pq: database \"pgexporter\" does not exist"
-- | --

After CREATE DATABASE pgexporter and adding all mandatory roles, it did work without errors.

Is that the expected behavior? I wouldn't use this database and use existing ones.

I saw the values parameter config.datasource.database but as I use several databases, is there a wildcard? Is this even the place where I can handle this behavior?

Thanks for clarification!

Environment

• System information:

  x86

• postgres_exporter version:

  4.4.3

• postgres_exporter values.yaml:

 pgExporter:
    enabled: true
    monitorUser: pgexporter
    monitorCred: testpwforghissue
---
prometheus-postgres-exporter:
  # it is always enabled, to disbable the exporter, see .Values.global.pgExporter
  enabled: true
  fullnameOverride: prometheus-postgres-exporter
  config:
    datasource:
      host: postgresql-primary
      name: pgExporter
      passwordSecret:
        name: prometheus-postgres-exporter-secret
        key: password
    externalQueries:
      enabled: true
      configmap: pgexporter-monitor-queries
  serviceMonitor:
    enabled: true

• PostgreSQL version:

  PostgreSQL 14.5 on x86_64-pc-linux-gnu, compiled by gcc (Debian 10.2.1-6) 10.2.1 20210110, 64-bit

• Logs:

2023-05-23 12:34:08.136 | ts=2023-05-23T10:34:08.135Z caller=collector.go:196 level=error msg="collector failed" name=bgwriter duration_seconds=0.008667515 err="pq: database \"pgexporter\" does not exist"
-- | --

[jfagoagas]

I don't know much about that Helm chart but this error occurs when you don't set any database name in the DSN. By default, pq takes the username as the database name if the latter is not set.

• postresql://user:password@host --> database name = user
• postresql://user:password@host/database --> database name = database

I think if you modify the DSN to include the database name your error will be gone. Regarding which DB you should set, I think postgres could be good but if you have just one DB set that to be able to get table metrics.

I think that a new ENV to set the DB Name will be good but I'm not sure what is the path to follow because they want to focus this exporter on the server metrics not at DB level.