When Postfix is running in a Docker container, it's most useful to use
the built-in Docker logging (as with Systemd). Setting
`--docker.enable` allows that.

The log source is using `client.NewEnvClient`, which reads environment
variables to determine which Docker to connect to, and how TLS is
handled.

2021-03-16 15:37:29 +01:00

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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.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/maillog`
`--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	`""`

Events from Docker

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

Default the exporter is build with systemd journal functionality (but it is disabled at default). Because the systemd headers are required for building with systemd, there is an option to build the exporter without systemd. Use the build tag nosystemd.

go build -tags nosystemd

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