Sensu Check Postfix

Description

This plugin provides native Postfix instrumentation for monitoring and metrics collection of the mail queue via mailq.

The plugin includes:

• check-mailq: Monitor mail queue size with configurable warning and critical thresholds
• metrics-mailq: Collect mail queue metrics in Graphite format for time-series databases
• check-mail-delay: Monitor mail queue message delays with configurable age thresholds

All commands work with Postfix mail queues and use the standard mailq command to retrieve queue information.

Installation

Binary Releases

Download the latest release from the releases page.

From Source

go install github.com/nmollerup/sensu-check-postfix/cmd/check-mailq@latest
go install github.com/nmollerup/sensu-check-postfix/cmd/metrics-mailq@latest
go install github.com/nmollerup/sensu-check-postfix/cmd/check-mail-delay@latest

Configuration

Asset Registration

Assets are the recommended way to install plugins in Sensu. The asset can be configured using sensuctl:

sensuctl asset add nmollerup/sensu-check-postfix

Check Definition

Example check definition:

---
type: CheckConfig
api_version: core/v2
metadata:
  name: check-mailq
spec:
  command: check-mailq --warning 200 --critical 400
  subscriptions:
    - linux
  runtime_assets:
    - nmollerup/sensu-check-postfix
  interval: 60
  publish: true

Usage

check-mailq

Monitor the size of the Postfix mail queue.

Sensu check to monitor Postfix mail queue size

Usage:
  check-mailq [flags]

Flags:
  -c, --critical int        Number of messages in the queue considered to be critical (default 0)
  -h, --help                help for check-mailq
  -p, --path string         Path to the postfix mailq binary (default "/usr/bin/mailq")
  -q, --queue string        The queue to check (active, deferred, hold, incoming, or all) (default "all")
  -w, --warning int         Number of messages in the queue considered to be a warning (default 0)

Examples

Check with default thresholds:

check-mailq --warning 200 --critical 400

Check a specific queue:

check-mailq --queue deferred --warning 100 --critical 200

Check with custom mailq path:

check-mailq --path /usr/local/bin/mailq --warning 50 --critical 100

Check using environment variables:

CHECK_MAILQ_WARNING=200 CHECK_MAILQ_CRITICAL=400 check-mailq

Output

The check will output one of the following states:

• OK: Message count is below the warning threshold
• WARNING: Message count is at or above the warning threshold but below the critical threshold
• CRITICAL: Message count is at or above the critical threshold
• UNKNOWN: Unable to read queue or invalid thresholds

Example outputs:

CheckMailq OK: 15 messages in the postfix mail queue
CheckMailq WARNING: 250 messages in the postfix mail queue
CheckMailq CRITICAL: 450 messages in the postfix mail queue

metrics-mailq

Collect mail queue metrics in Graphite format.

Sensu metric plugin to collect Postfix mail queue metrics

Usage:
  metrics-mailq [flags]

Flags:
  -h, --help           help for metrics-mailq
  -p, --path string    Path to the postfix mailq binary (default "/usr/bin/mailq")
  -s, --scheme string  Metric naming scheme, text to prepend to metric (default: hostname)

Examples

Collect metrics with default scheme:

metrics-mailq
# Output: hostname.postfixMailqCount 15 1738367100

Collect metrics with custom scheme:

metrics-mailq --scheme production.mailserver01
# Output: production.mailserver01.postfixMailqCount 15 1738367100

Example metric check definition:

---
type: CheckConfig
api_version: core/v2
metadata:
  name: metrics-mailq
spec:
  command: metrics-mailq
  subscriptions:
    - linux
  runtime_assets:
    - nmollerup/sensu-check-postfix
  interval: 60
  publish: true
  output_metric_format: graphite_plaintext
  output_metric_handlers:
    - influxdb

check-mail-delay

Monitor message delays in the Postfix mail queue.

Sensu check to monitor Postfix mail queue message delays

Usage:
  check-mail-delay [flags]

Flags:
  -c, --critical int        Age in seconds of messages considered to be critical (default 7200)
  -h, --help                help for check-mail-delay
  -p, --path string         Path to the postfix mailq binary (default "/usr/bin/mailq")
  -q, --queue string        The queue to check (active, deferred, hold, incoming, or all) (default "all")
  -w, --warning int         Age in seconds of messages considered to be a warning (default 3600)

Examples

Check with default thresholds (warning: 1 hour, critical: 2 hours):

check-mail-delay

Check with custom age thresholds:

check-mail-delay --warning 1800 --critical 3600

Check a specific queue:

check-mail-delay --queue deferred --warning 7200 --critical 14400

Check using environment variables:

CHECK_MAIL_DELAY_WARNING=1800 CHECK_MAIL_DELAY_CRITICAL=3600 check-mail-delay

Output

The check will output one of the following states:

• OK: No messages older than the warning threshold
• WARNING: Messages exist that are older than the warning threshold but younger than the critical threshold
• CRITICAL: Messages exist that are older than the critical threshold
• UNKNOWN: Unable to read queue or invalid thresholds

Example outputs:

PostfixMailDelay OK: 0 messages in the postfix mail queue older than 3600 seconds
PostfixMailDelay WARNING: 5 messages in the postfix mail queue older than 3600 seconds
PostfixMailDelay CRITICAL: 10 messages in the postfix mail queue older than 7200 seconds

Platform Support

This plugin is designed for Linux systems with Postfix installed. It requires:

• Postfix mail server
• mailq command (typically at /usr/bin/mailq)
• Access to Postfix queue directories (for specific queue checks)

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

MIT License - see LICENSE file for details.