Prometheus Postfix exporter

Prometheus metrics exporter for the Postfix mail server. This exporter provides histogram metrics for the size and age of messages stored in the mail queue. It extracts these metrics from Postfix by connecting to a UNIX socket under /var/spool. It also counts events by parsing Postfix's log entries, using regular expression matching. The log entries are retrieved from the systemd journal, the Docker logs, or from a log file.

Options

These options can be used when starting the postfix_exporter

Flag	Description	Default
--web.listen-address	Address to listen on for web interface and telemetry	9154
--web.config.file	Path to configuration file that can enable TLS or authentication (ref).	""
--web.telemetry-path	Path under which to expose metrics	/metrics
--postfix.showq_path	Path at which Postfix places its showq socket	/var/spool/postfix/public/showq
--postfix.logfile_path	Path where Postfix writes log entries	/var/log/mail.log
--postfix.logfile_must_exist	Fail if the log file doesn't exist.	true
--postfix.logfile_debug	Enable debug logging for the log file.	false
--log.unsupported	Log all unsupported lines	false
--docker.enable	Read from the Docker logs instead of a file	false
--docker.container.id	The container to read Docker logs from	postfix
--systemd.enable	Read from the systemd journal instead of file	false
--systemd.unit	Name of the Postfix systemd unit	postfix.service
--systemd.slice	Name of the Postfix systemd slice.	""
--systemd.journal_path	Path to the systemd journal	""

The --docker.* flags are not available for binaries built with the nodocker build tag. The --systemd.* flags are not available for binaries built with the nosystemd build tag.

Events from Docker

If postfix_exporter is built with docker support, postfix servers running in a Docker container can be monitored using the --docker.enable flag. The default container ID is postfix, but can be customized with the --docker.container.id flag.

The default is to connect to the local Docker, but this can be customized using the DOCKER_HOST and similar environment variables.

Events from log file

The log file is tailed when processed. Rotating the log files while the exporter is running is OK. The path to the log file is specified with the --postfix.logfile_path flag.

Events from systemd

Retrieval from the systemd journal is enabled with the --systemd.enable flag. This overrides the log file setting. It is possible to specify the unit (with --systemd.unit) or slice (with --systemd.slice). Additionally, it is possible to read the journal from a directory with the --systemd.journal_path flag.

Build options

By default, the exporter is built without docker and systemd support.

go build -tags nosystemd,nodocker

To build the exporter with support for docker or systemd, remove the relevant build build tag from the build arguments. Note that systemd headers are required for building with systemd. On Debian-based systems, this is typically achieved by installing the libsystemd-dev APT package.

go build -tags nosystemd

Releases

Signed container images are provided from the GitHub Container Registry (https://github.com/Hsn723/postfix_exporter/pkgs/container/postfix_exporter). The binary included in container images is built without docker and systemd support.

The Releases page includes signed pre-built binaries for various configurations.

• postfix_exporter binaries are minimal builds (docker and systemd support excluded)
• postfix_exporter_docker binaries have docker support built-in
• postfix_exporter_systemd binaries have systemd support built-in
• postfix_exporter_aio binaries are built with everything included, which can be useful for packaging for systems where the final use-case is not known in advance