#!/bin/python3
import time
import sys
import re
import os
import croniter
import subprocess

name = sys.argv[1]
cron_expr = sys.argv[2]
cmd = sys.argv[3]
exporterdir = '/var/lib/prometheus/node-exporter'

label_name = name.replace('\\', '\\\\').replace('"', '\\"').replace('\n', '\\n')
file_name = re.sub('[^a-zA-Z0-9]', '_', name)

start_ts = time.time()
result = subprocess.run(cmd, shell=True)
end_ts = time.time()

next_ts = croniter.croniter(cron_expr).get_next()

jobstats = f'''# Generated by monitor-cronjob.py

# HELP cron_job_last_run_seconds Unix timestamp of last run
# TYPE cron_job_last_run_seconds counter
cron_job_last_run_seconds{{name="{ label_name }"}} { start_ts }

# HELP cron_job_exit_code Exit code of last run
# TYPE cron_job_exit_code gauge
cron_job_exit_code{{name="{ label_name }"}} { result.returncode }

# HELP cron_job_duration_seconds Duration of last run
# TYPE cron_job_duration_seconds gauge
cron_job_duration_seconds{{name="{ label_name }"}} { end_ts - start_ts }

# HELP cron_job_next_run_seconds Unix timestamp of next run
# TYPE cron_job_next_run_seconds counter
cron_job_next_run_seconds{{name="{ label_name }"}} { next_ts }
'''

successstats = f'''# Generated by monitor-cronjob.py

# HELP cron_job_last_success_seconds Unix timestamp of last successful run
# TYPE cron_job_last_success_seconds counter
cron_job_last_success_seconds{{name="{ label_name }"}} { start_ts }
'''

tmpsuffix = '.%d'%(os.getpid())

path = os.path.join(exporterdir, f'cron_job_generic_{ file_name }.prom')
with open(path + tmpsuffix, 'w') as f:
	f.write(jobstats)
os.rename(path + tmpsuffix, path)

if result.returncode == 0:
	path = os.path.join(exporterdir, f'cron_job_success_{ file_name }.prom')
	with open(path + tmpsuffix, 'w') as f:
		f.write(successstats)
	os.rename(path + tmpsuffix, path)