Logger: MQTT Client

MQTT (Message Queuing Telemetry Transport) logger for publishing DNS logs to an MQTT broker.

Options:

• remote-address: (string) MQTT broker address
• remote-port: (integer) MQTT broker port
• topic: (string) MQTT topic to publish to
• qos: (integer) MQTT QoS level (0, 1, or 2), default: 0
• protocol-version: (string) MQTT protocol version ("v3", "v5", or "auto"), default: "auto"
• username: (string) username for authentication, optional
• password: (string) password for authentication, optional
• connect-timeout: (integer) connection timeout in seconds, default: 5
• retry-interval: (integer) reconnection retry interval in seconds, default: 10
• tls-support: (boolean) enable TLS, default: false
• tls-insecure: (boolean) skip TLS verification, default: false
• tls-min-version: (string) minimum TLS version (1.0, 1.1, 1.2, 1.3), default: "1.2"
• ca-file: (string) path to CA certificate file for TLS, optional
• cert-file: (string) path to client certificate file for TLS, optional
• key-file: (string) path to client key file for TLS, optional
• mode: (string) output format ("text", "json", or "flat-json"), default: "flat-json"
• text-format: (string) custom text format (only when mode is "text")
• buffer-size: (integer) maximum buffer size before flush, default: 100
• flush-interval: (integer) flush interval in seconds, default: 10
• chan-buffer-size: (integer) channel buffer size, default: 65535

Default values:

mqtt:
  remote-address: 127.0.0.1
  remote-port: 1883
  topic: "dns/logs"
  qos: 0
  protocol-version: "auto"
  connect-timeout: 5
  retry-interval: 10
  tls-support: false
  tls-insecure: false
  tls-min-version: "1.2"
  mode: "flat-json"
  buffer-size: 100
  flush-interval: 10
  chan-buffer-size: 65535

Examples

Basic MQTT Connection

pipelines:
  - name: mqtt-logger
    mqtt:
      remote-address: "mqtt.example.com"
      remote-port: 1883
      topic: "dns/queries"
      qos: 1

MQTT with TLS

pipelines:
  - name: mqtt-secure
    mqtt:
      remote-address: "mqtt.example.com"
      remote-port: 8883
      topic: "dns/secure"
      tls-support: true
      tls-insecure: false
      ca-file: "/path/to/ca.crt"
      cert-file: "/path/to/client.crt"
      key-file: "/path/to/client.key"

MQTT with Authentication

pipelines:
  - name: mqtt-auth
    mqtt:
      remote-address: "mqtt.example.com"
      remote-port: 1883
      topic: "dns/logs"
      username: "dnsuser"
      password: "secretpass"
      qos: 2

MQTT v5 with JSON Output

pipelines:
  - name: mqtt-v5
    mqtt:
      remote-address: "mqtt.example.com"
      remote-port: 1883
      topic: "dns/json"
      protocol-version: "v5"
      mode: "json"
      qos: 1

Custom Text Format

pipelines:
  - name: mqtt-text
    mqtt:
      remote-address: "127.0.0.1"
      remote-port: 1883
      topic: "dns/text"
      mode: "text"
      text-format: "timestamp-rfc3339ns identity qr queryip queryport family protocol operation rcode queryname querytype latency"

High-Throughput Configuration

pipelines:
  - name: mqtt-highthroughput
    mqtt:
      remote-address: "mqtt.example.com"
      remote-port: 1883
      topic: "dns/highvolume"
      qos: 0
      buffer-size: 1000
      flush-interval: 5
      chan-buffer-size: 100000

Protocol Version Selection

The protocol-version option controls which MQTT protocol to use:

• "v3": Force MQTT v3.1.1
• "v5": Force MQTT v5
• "auto": Try v5 first, fallback to v3.1.1 if rejected (default)

Auto-detection is recommended for maximum compatibility.

QoS Levels

MQTT supports three Quality of Service levels:

• QoS 0 (at most once): Fire and forget, no acknowledgment
• QoS 1 (at least once): Acknowledged delivery, possible duplicates
• QoS 2 (exactly once): Assured delivery, no duplicates

Choose based on your reliability requirements vs. performance needs.

Performance Considerations

• QoS 0 provides the highest throughput with lowest latency
• Increase buffer-size and chan-buffer-size for high-volume scenarios
• Decrease flush-interval for lower latency (at cost of more network traffic)
• Use flat-json mode for compact output, json for readable output

Reconnection Behavior

The logger automatically reconnects to the MQTT broker if the connection is lost:

• Initial connection timeout: connect-timeout seconds
• Reconnection attempts: every retry-interval seconds
• Messages are buffered during disconnection up to chan-buffer-size
• Buffered messages are published once reconnected