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Authored by FCeratto-WMF on Mon, Sep 14, 5:29 PM.

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	F102926783: raw-paste-data.txt
	Mon, Sep 14, 5:33 PM

	F102926642: raw-paste-data.txt
	Mon, Sep 14, 5:29 PM

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	import logging
	import time
	from prometheus_client import Gauge, REGISTRY, write_to_textfile
	from sqlalchemy import create_engine, text
	from sqlalchemy.engine import Engine

	logging.basicConfig(level=logging.INFO)
	log = logging.getLogger("my_textfile_exporter")

	# Prometheus metrics
	WEIGHT_GAUGE = Gauge(
	"mysql_instance_weight",
	"Weight of the MariaDB instance",
	["hostname", "instance_group", "section", "role"],
	)


	def fetch(engine: Engine, sql: str, params: dict \| None = None) -> list[dict]:
	with engine.begin() as tx:
	result = tx.execute(text(sql), params or {})
	return [dict(r._mapping) for r in result.fetchall()]


	def main() -> None:
	uri = "mysql+pymysql://user:pass@zarcillo.db.domain/zarcillo"
	output_path = "/var/lib/prometheus/node-exporter/mystuff.prom"

	engine: Engine = create_engine(uri, pool_pre_ping=True, future=True)

	sql = """
	SELECT a,b,c,myval FROM ...
	"""

	while True:
	try:
	rows = fetch(engine, sql)
	# We expect one row, myval is the metric value, everything else is a label
	row = rows[0]
	val = row.pop("myval")

	WEIGHT_GAUGE.clear()
	WEIGHT_GAUGE.labels(**row).set(float(val))

	# Write atomically
	write_to_textfile(output_path, REGISTRY)
	log.debug(f"Successfully wrote metrics to {output_path}")

	except Exception as e:
	log.error(f"Failed to generate metrics file: {e}")
	raise

	time.sleep(60)


	if __name__ == "__main__":
	main()

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