#!/usr/bin/python3
# Mail the tail of a failed unit's journal. Usage: restic-alert <unit>
import os, smtplib, socket, subprocess, sys
from email.message import EmailMessage

unit = sys.argv[1]
env = dict(l.rstrip("\n").split("=", 1) for l in open("/etc/restic/env") if "=" in l)
log = subprocess.run(["journalctl", "-u", unit, "-n", "60", "--no-pager", "-o", "cat"],
                     capture_output=True, text=True).stdout

msg = EmailMessage()
msg["Subject"] = f"[{socket.gethostname()}] {unit} failed"
msg["From"] = env["ALERT_SMTP_USER"]
msg["To"] = env["ALERT_RECIPIENT"]
msg.set_content(log)

with smtplib.SMTP(env["ALERT_SMTP_HOST"], int(env["ALERT_SMTP_PORT"]), timeout=30) as s:
    s.starttls()
    s.login(env["ALERT_SMTP_USER"], env["ALERT_SMTP_PASSWORD"])
    s.send_message(msg)