vsql-prometheus-exporter

Prometheus exporter extension for VillageSQL Server, built using the VillageSQL Extension Framework (VEF).

Exposes MySQL server metrics at an HTTP /metrics endpoint in Prometheus exposition format.

Metrics

Prefix	Source	Description
mysql_global_status_	SHOW GLOBAL STATUS	Server status variables
mysql_global_variables_	SHOW GLOBAL VARIABLES	Numeric server variables
mysql_info_schema_innodb_metrics_	information_schema.innodb_metrics	InnoDB internal metrics
mysql_replica_	SHOW REPLICA STATUS	Replication status (when applicable)

Built-in operational metrics:

Metric	Description
requests_total	Total HTTP scrape requests
scrape_duration_us	Scrape duration in microseconds
errors_total	Total scrape errors

System Variables

Variable	Default	Description
prometheus_exporter.enabled	OFF	Enable/disable the exporter
prometheus_exporter.port	9104	HTTP listen port
prometheus_exporter.bind_address	127.0.0.1	HTTP listen address

CI Testing

Every pull request is tested against VillageSQL Server (tomas/dev branch). The CI workflow:

1. Builds VillageSQL Server from source
2. Builds the extension and packages it as a .veb bundle
3. Runs the MTR test suite with 6 tests:

Test	What it verifies
basic	Install/uninstall lifecycle, system variables, HTTP listener start/stop
format_validation	Prometheus exposition format correctness (metric lines, numeric values)
global_variables	mysql_global_variables_ metrics exported for known numeric variables
metrics_endpoint	HTTP 200 on /metrics, 404 on unknown paths, all collector prefixes present
replica_status	mysql_replica_* metrics behavior on non-replica server
scrape_counter	requests_total increments per scrape, scrape_duration_us > 0, no errors

Quick Start

INSTALL EXTENSION prometheus_exporter;
SET GLOBAL prometheus_exporter.port = 9104;
SET GLOBAL prometheus_exporter.enabled = ON;

Then scrape http://127.0.0.1:9104/metrics.