feat(chatmaild/fsreport): add Prometheus textfile output, count files

- Count files in report
- Extend size buckets to bigger messages (5, 10 MiB)
- Two textfile exporters:
  - Full, bucketed size statistics with --textfile option
  - Account count only matching metrics.py format with --legacy-metrics
    option (filename defaults to /var/www/html/metrics)
- Improve option help texts

chatmaild/src/chatmaild/fsreport.py

@@ -13,9 +13,20 @@ to show storage summaries only for first 1000 mailboxes
 
     python -m chatmaild.fsreport /path/to/chatmail.ini --maxnum 1000
 
+to write Prometheus textfile for node_exporter
+
+    python -m chatmaild.fsreport --textfile /var/lib/prometheus/node-exporter/
+
+writes to /var/lib/prometheus/node-exporter/fsreport.prom
+
+to also write legacy metrics.py style output (default: /var/www/html/metrics):
+
+    python -m chatmaild.fsreport --textfile /var/lib/prometheus/node-exporter/ --legacy-metrics
+
 """
 
 import os
+import tempfile
 from argparse import ArgumentParser
 from datetime import datetime
 
@@ -48,7 +59,19 @@ class Report:
         self.num_ci_logins = self.num_all_logins = 0
         self.login_buckets = {x: 0 for x in (1, 10, 30, 40, 80, 100, 150)}
 
-        self.message_buckets = {x: 0 for x in (0, 160000, 500000, 2000000)}
+        KiB = 1024
+        MiB = 1024 * KiB
+        self.message_size_thresholds = (
+            0,
+            100 * KiB,
+            MiB // 2,
+            1 * MiB,
+            2 * MiB,
+            5 * MiB,
+            10 * MiB,
+        )
+        self.message_buckets = {x: 0 for x in self.message_size_thresholds}
+        self.message_count_buckets = {x: 0 for x in self.message_size_thresholds}
 
     def process_mailbox_stat(self, mailbox):
         # categorize login times
@@ -71,6 +94,7 @@ class Report:
                         if self.mdir and f"/{self.mdir}/" not in msg.path:
                             continue
                         self.message_buckets[size] += msg.size
+                        self.message_count_buckets[size] += 1
 
         self.size_messages += sum(entry.size for entry in mailbox.messages)
         self.size_extra += sum(entry.size for entry in mailbox.extrafiles)
@@ -93,9 +117,10 @@ class Report:
 
         pref = f"[{self.mdir}] " if self.mdir else ""
         for minsize, sumsize in self.message_buckets.items():
+            count = self.message_count_buckets[minsize]
             percent = (sumsize / all_messages * 100) if all_messages else 0
             print(
-                f"{pref}larger than {HSize(minsize)}: {HSize(sumsize)} ({percent:.2f}%)"
+                f"{pref}larger than {HSize(minsize)}: {HSize(sumsize)} ({percent:.2f}%), {count} msgs"
             )
 
         user_logins = self.num_all_logins - self.num_ci_logins
@@ -111,6 +136,75 @@ class Report:
         for days, active in self.login_buckets.items():
             print(f"last {days:3} days: {HSize(active)} {p(active)}")
 
+    def _write_atomic(self, filepath, content):
+        """Atomically write content to filepath via tmp+rename."""
+        dirpath = os.path.dirname(os.path.abspath(filepath))
+        fd, tmppath = tempfile.mkstemp(dir=dirpath, suffix=".tmp")
+        try:
+            with os.fdopen(fd, "w") as f:
+                f.write(content)
+            os.chmod(tmppath, 0o644)
+            os.rename(tmppath, filepath)
+        except BaseException:
+            try:
+                os.unlink(tmppath)
+            except OSError:
+                pass
+            raise
+
+    def dump_textfile(self, filepath):
+        """Dump metrics in Prometheus exposition format."""
+        lines = []
+
+        lines.append("# HELP chatmail_storage_bytes Mailbox storage in bytes.")
+        lines.append("# TYPE chatmail_storage_bytes gauge")
+        lines.append(f'chatmail_storage_bytes{{kind="messages"}} {self.size_messages}')
+        lines.append(f'chatmail_storage_bytes{{kind="extra"}} {self.size_extra}')
+        total = self.size_extra + self.size_messages
+        lines.append(f'chatmail_storage_bytes{{kind="total"}} {total}')
+
+        lines.append("# HELP chatmail_messages_bytes Sum of msg bytes >= threshold.")
+        lines.append("# TYPE chatmail_messages_bytes gauge")
+        for minsize, sumsize in self.message_buckets.items():
+            lines.append(f'chatmail_messages_bytes{{min_size="{minsize}"}} {sumsize}')
+
+        lines.append("# HELP chatmail_messages_count Number of msgs >= size threshold.")
+        lines.append("# TYPE chatmail_messages_count gauge")
+        for minsize, count in self.message_count_buckets.items():
+            lines.append(f'chatmail_messages_count{{min_size="{minsize}"}} {count}')
+
+        lines.append("# HELP chatmail_accounts Number of accounts.")
+        lines.append("# TYPE chatmail_accounts gauge")
+        user_logins = self.num_all_logins - self.num_ci_logins
+        lines.append(f'chatmail_accounts{{kind="all"}} {self.num_all_logins}')
+        lines.append(f'chatmail_accounts{{kind="ci"}} {self.num_ci_logins}')
+        lines.append(f'chatmail_accounts{{kind="user"}} {user_logins}')
+
+        lines.append(
+            "# HELP chatmail_accounts_active Non-CI accounts active within N days."
+        )
+        lines.append("# TYPE chatmail_accounts_active gauge")
+        for days, active in self.login_buckets.items():
+            lines.append(f'chatmail_accounts_active{{days="{days}"}} {active}')
+
+        self._write_atomic(filepath, "\n".join(lines) + "\n")
+
+    def dump_compat_textfile(self, filepath):
+        """Dump legacy metrics.py style metrics."""
+        user_logins = self.num_all_logins - self.num_ci_logins
+        lines = [
+            "# HELP total number of accounts",
+            "# TYPE accounts gauge",
+            f"accounts {self.num_all_logins}",
+            "# HELP number of CI accounts",
+            "# TYPE ci_accounts gauge",
+            f"ci_accounts {self.num_ci_logins}",
+            "# HELP number of non-CI accounts",
+            "# TYPE nonci_accounts gauge",
+            f"nonci_accounts {user_logins}",
+        ]
+        self._write_atomic(filepath, "\n".join(lines) + "\n")
+
 
 def main(args=None):
     """Report about filesystem storage usage of all mailboxes and messages"""
@@ -127,19 +221,21 @@ def main(args=None):
         "--days",
         default=0,
         action="store",
-        help="assume date to be days older than now",
+        help="assume date to be DAYS older than now",
     )
     parser.add_argument(
         "--min-login-age",
         default=0,
+        metavar="DAYS",
         dest="min_login_age",
         action="store",
-        help="only sum up message size if last login is at least min-login-age days old",
+        help="only sum up message size if last login is at least DAYS days old",
     )
     parser.add_argument(
         "--mdir",
+        metavar="{cur,new,tmp}",
         action="store",
-        help="only consider 'cur' or 'new' or 'tmp' messages for summary",
+        help="only consider messages in specified Maildir subdirectory for summary",
     )
 
     parser.add_argument(
@@ -148,6 +244,21 @@ def main(args=None):
         action="store",
         help="maximum number of mailboxes to iterate on",
     )
+    parser.add_argument(
+        "--textfile",
+        metavar="PATH",
+        default=None,
+        help="write Prometheus textfile to PATH (directory or file); "
+        "if PATH is a directory, writes 'fsreport.prom' inside it",
+    )
+    parser.add_argument(
+        "--legacy-metrics",
+        metavar="FILENAME",
+        nargs="?",
+        const="/var/www/html/metrics",
+        default=None,
+        help="write legacy metrics.py textfile (default: /var/www/html/metrics)",
+    )
 
     args = parser.parse_args(args)
 
@@ -161,7 +272,15 @@ def main(args=None):
     rep = Report(now=now, min_login_age=int(args.min_login_age), mdir=args.mdir)
     for mbox in iter_mailboxes(str(config.mailboxes_dir), maxnum=maxnum):
         rep.process_mailbox_stat(mbox)
-    rep.dump_summary()
+    if args.textfile:
+        path = args.textfile
+        if os.path.isdir(path):
+            path = os.path.join(path, "fsreport.prom")
+        rep.dump_textfile(path)
+    if args.legacy_metrics:
+        rep.dump_compat_textfile(args.legacy_metrics)
+    if not args.textfile and not args.legacy_metrics:
+        rep.dump_summary()
 
 
 if __name__ == "__main__":

cmdeploy/src/cmdeploy/service/chatmail-fsreport.service.f

@@ -5,5 +5,5 @@ After=network.target
 [Service]
 Type=oneshot
 User=vmail
-ExecStart=/usr/local/lib/chatmaild/venv/bin/chatmail-fsreport /usr/local/lib/chatmaild/chatmail.ini 
+ExecStart=/usr/local/lib/chatmaild/venv/bin/chatmail-fsreport /usr/local/lib/chatmaild/chatmail.ini