add ansible role journal-postfix (a log parser for Postfix) with playbook and doc

journal-postfix/files/srv/settings.py

@@ -0,0 +1,125 @@
+#!/usr/bin/env python3
+
+"""
+Settings for journal-postfix.
+"""
+
+import os
+import datetime
+from typing import Union, Optional
+from systemd import journal
+from yaml import load
+
+
+main_config_file: str = '/etc/journal-postfix/main.yml'
+"""
+Filepath to the main config file.
+
+Can be overriden by environment variable JOURNAL_POSTFIX_MAIN_CONF.
+"""
+
+
+systemd_unitname: str = 'postfix@-.service'
+"""
+Name of the systemd unit running the postfix service.
+"""
+
+
+journal_poll_interval: Union[float, int] = 10.0
+"""
+Poll timeout in seconds for fetching messages from the journal.
+
+Will be overriden if set in the main config.
+
+If the poll times out, it is checked whether the last commit
+lies more than max_delay_before_commit seconds in the past;
+if so, the current database transaction will be committed.
+"""
+
+
+max_delay_before_commit: datetime.timedelta = datetime.timedelta(seconds=30)
+"""
+How much time may pass before committing a database transaction?
+
+Will be overriden if set in the main config.
+
+(The actual maximal delay can be one journal_poll_interval in addition.)
+"""
+
+
+max_messages_per_commit: int = 1000
+"""
+How many messages to cache at most before committing a database transaction?
+
+Will be overriden if set in the main config.
+"""
+
+
+delete_deliveries_after_days: int = 0
+"""
+After how many days shall deliveries be deleted from the database?
+
+A value of 0 means that data are never deleted.
+"""
+
+
+def get_config() -> Optional[dict]:
+    """
+    Load config from the main config and return it.
+
+    The default main config file path (global main_config_file)
+    can be overriden with environment variable
+    JOURNAL_POSTFIX_MAIN_CONF.
+    """
+    try:
+        filename = os.environ['JOURNAL_POSTFIX_MAIN_CONF']
+        global main_config_file
+        main_config_file = filename
+    except Exception:
+        filename = main_config_file
+    try:
+        with open(filename, 'r') as config_file:
+            config_raw = config_file.read()
+    except Exception:
+        msg = f'ERROR: cannot read config file {filename}'
+        journal.send(msg, PRIORITY=journal.LOG_CRIT)
+        return None
+    try:
+        config = load(config_raw)
+    except Exception as err:
+        msg = f'ERROR: invalid yaml syntax in {filename}: {err}'
+        journal.send(msg, PRIORITY=journal.LOG_CRIT)
+        return None
+    # override some global variables
+    _global_value_from_config(config['postfix'], 'systemd_unitname', str)
+    _global_value_from_config(config, 'journal_poll_interval', float)
+    _global_value_from_config(config, 'max_delay_before_commit', 'seconds')
+    _global_value_from_config(config, 'max_messages_per_commit', int)
+    _global_value_from_config(config, 'delete_deliveries_after_days', int)
+    _global_value_from_config(config, 'delete_interval', 'seconds')
+    return config
+
+
+def _global_value_from_config(
+    config, name: str, type_: Union[type, str]
+) -> None:
+    """
+    Set a global variable to the value obtained from *config*.
+
+    Also cast to *type_*.
+    """
+    try:
+        value = config.get(name)
+        if type_ == 'seconds':
+            value = datetime.timedelta(seconds=float(value))
+        else:
+            value = type_(value)  # type: ignore
+        globals()[name] = value
+    except Exception:
+        if value is not None:
+            msg = f'ERROR: configured value of {name} is invalid.'
+            journal.send(msg, PRIORITY=journal.LOG_ERR)
+
+
+if __name__ == '__main__':
+    print(get_config())