Postgres Exporter 0.20.1-1

postgres_exporter gives Prometheus the PostgreSQL app's metrics - its activity, transactions, cache hits, locks and database sizes - with a Grafana dashboard. It's for the Prometheus and Grafana apps: once they're installed (in any order), Prometheus collects its metrics every 30 seconds, and its dashboard (PostgreSQL) is in Grafana's NAS folder. It runs natively on the NAS (no Docker).

• It needs the PostgreSQL app (installed first). It logs in as postgres_exporter, a login the app creates with a password only it keeps (in Nas_Prog/_postgres_exporter, root's), as a member of pg_monitor: it can read PostgreSQL's statistics, not your data. At boot PostgreSQL may start after it: the login is then set up as soon as PostgreSQL answers.
• It listens on the NAS itself only (127.0.0.1:9187) and runs as its own user (postgres_exporter, ID 89). Its files are kept in Nas_Prog/_postgres_exporter, across reinstalls and removal.
• Its page shows whether it reaches PostgreSQL, whether Prometheus collects its metrics, and links to its dashboard. Set up its login again makes a new password (e.g. after PostgreSQL's data was started afresh).
• Its scrape job is prometheus/postgres.yml and its dashboard dashboards/postgresql.json: the Prometheus and Grafana apps pick up every app's (see their READMEs), and drop them when the app is removed.
• The dashboard is postgres_exporter's own dashboard (postgres_mixin/dashboards/postgres-overview.json, Apache-2.0), unchanged apart from its title, a nas tag, and its Buffers panel brought up to PostgreSQL 17 and later (checkpoints' buffers from pg_stat_checkpointer, which the app collects - backends' writes are no longer counted there).
• It's the official static program, checked against the SHA256 its release publishes (pinned in static/postgres_exporter/build.sh). Intel models only.