Add log rotation (if logging to file). Make rsyslog the default.

core/postfix/Dockerfile

@@ -19,7 +19,7 @@ RUN apk add --no-cache --virtual .build-deps gcc musl-dev python3-dev
 RUN pip3 install --no-binary :all: postfix-mta-sts-resolver==1.0.1
 RUN apk del .build-deps gcc musl-dev python3-dev
 
-RUN apk add --no-cache postfix postfix-pcre cyrus-sasl-login rsyslog
+RUN apk add --no-cache postfix postfix-pcre cyrus-sasl-login rsyslog logrotate
 
 COPY conf /conf
 COPY start.py /start.py

core/postfix/conf/logrotate.conf

@@ -0,0 +1,11 @@
+{{POSTFIX_LOG_FILE}} {
+weekly
+rotate 52
+nocompress
+extension log
+create 0644 root root
+      postrotate
+          /bin/kill -HUP $(cat /run/rsyslogd.pid)
+          postfix reload
+      endscript
+}

core/postfix/conf/rsyslog.conf

@@ -33,7 +33,7 @@ module(load="imuxsock")
 
 {% if POSTFIX_LOG_FILE %}
 # Log mail logs to file
-mail.*							-{{LOG_FILE}}
+mail.*							-{{POSTFIX_LOG_FILE}}
 {% endif %}
 
 # Log mail logs to stdout

core/postfix/start.py

@@ -46,7 +46,8 @@ os.environ["FRONT_ADDRESS"] = system.get_host_address_from_environment("FRONT",
 os.environ["ADMIN_ADDRESS"] = system.get_host_address_from_environment("ADMIN", "admin")
 os.environ["ANTISPAM_MILTER_ADDRESS"] = system.get_host_address_from_environment("ANTISPAM_MILTER", "antispam:11332")
 os.environ["LMTP_ADDRESS"] = system.get_host_address_from_environment("LMTP", "imap:2525")
-os.environ["POSTFIX_LOG_SYSLOG"] = os.environ.get("POSTFIX_LOG_SYSLOG","disabled")
+os.environ["POSTFIX_LOG_SYSLOG"] = os.environ.get("POSTFIX_LOG_SYSLOG","local")
+os.environ["POSTFIX_LOG_FILE"] = os.environ.get("POSTFIX_LOG_FILE", "")
 
 for postfix_file in glob.glob("/conf/*.cf"):
     conf.jinja(postfix_file, os.environ, os.path.join("/etc/postfix", os.path.basename(postfix_file)))
@@ -85,6 +86,11 @@ if os.environ["POSTFIX_LOG_SYSLOG"]=="local":
     # Configure and start local rsyslog server
     conf.jinja("/conf/rsyslog.conf", os.environ, "/etc/rsyslog.conf")
     os.system("/usr/sbin/rsyslogd -n &")
+    # Configure logrotate
+    if os.environ["POSTFIX_LOG_FILE"] != "":
+        conf.jinja("/conf/logrotate.conf", os.environ, "/etc/logrotate.d/postfix.conf")
+        if os.path.exists("/overrides/logrotate.conf"):
+            shutil.copyfile("/overrides/logrotate.conf", "/etc/logrotate.d/postfix.conf")
 
 # Run Podop and Postfix
 multiprocessing.Process(target=start_podop).start()

docs/configuration.rst

@@ -188,9 +188,6 @@ Log messages equal or higher than this priority will be printed.
 Can be one of: CRITICAL, ERROR, WARNING, INFO, DEBUG or NOTSET.
 See the `python docs`_ for more information.
 
-``POSTFIX_LOG_FILE`` enables postfix logging to the given file (in addition to log to stdout).
-Log rotation should be done externally.
-
 .. _`python docs`: https://docs.python.org/3.6/library/logging.html#logging-levels
 
 The ``LETSENCRYPT_SHORTCHAIN`` (default: False) setting controls whether we send the ISRG Root X1 certificate in TLS handshakes. This is required for `android handsets older than 7.1.1` but slows down the performance of modern devices.
@@ -270,8 +267,11 @@ Mail log settings
 
 By default, all services log directly to stdout/stderr. Logs can be collected by any docker log processing solution.
 
-In some situations, a separate mail log is required (e.g. for legal reasons). Postfix can be configured to write the logs to a
+Postfix writes the logs to a syslog server which logs to stdout. This is used to filter out messages from the healthcheck.
-syslog server that stores the log files to a volume. It can be configured by the following options:
+In some situations, a separate mail log is required (e.g. for legal reasons). The syslog server can be configured to write log files to a volume. It can be configured by the following options:
 
-- ``POSTFIX_LOG_SYSLOG``: (default: ``disabled``) set to ``local`` to enable a local syslog server for postfix
+- ``POSTFIX_LOG_SYSLOG`` (default: ``local`` ): Set to ``local`` (default) to enable the syslog server. Set to ``disable`` to disable the syslog server. If disabled, Postfix will log directly to stdout and the healthcheck messages will not be filtered out.
-- ``POSTFIX_LOG_FILE``: The file to log the mail log to
+- ``POSTFIX_LOG_FILE``: The file to log the mail log to. When enabled, the syslog server will also log to stdout.
+
+When ``POSTFIX_LOG_FILE`` is enabled, the logrotate program will automatically rotate the logs every week and keep 52 logs.
+To override the logrotate configuration, create the file logrotate.conf with the desired configuration in the :ref:`Postfix overrides folder<override-label>`.

docs/faq.rst

@@ -263,6 +263,7 @@ correct syntax. The following file names will be taken as override configuration
    - All ``$ROOT/overrides/postfix/*.map`` files
    - For both ``postfix.cf`` and ``postfix.master``, you need to put one configuration per line, as they are fed line-by-line
      to postfix.
+   - ``logrotate.conf`` as ``$ROOT/overrides/postfix/logrotate.conf`` - Replaces the logrotate.conf file used for rotating ``POSTFIX_LOG_FILE``.
 - `Dovecot`_ - ``dovecot.conf`` in dovecot sub-directory;
 - `Nginx`_ - All ``*.conf`` files in the ``nginx`` sub-directory;
 - `Rspamd`_ - All files in the ``rspamd`` sub-directory.