DNS Exporter for Prometheus

Overview

DNS Exporter is a Prometheus exporter that queries DNS records and exposes metrics related to query performance and success status.

This project was created as a result of issues with pdnsd, which caches DNS queries on hosts. The goal was to have a lightweight exporter to directly verify its operation on each server.

Features

• Supports querying multiple DNS records
• Configurable DNS server
• Uses miekg/dns library for DNS resolution
• Prometheus metrics for monitoring query time, success rate, and last check timestamp
• Configurable worker pool for parallel querying
• Graceful timeout handling for DNS requests

Installation

Prerequisites

• Go 1.18+
• Prometheus server

Build

# Clone the repository
git clone https://github.com/wwwlde/dns-exporter.git
cd dns-exporter

# Build the binary
go build -o ./dns-exporter --ldflags '-extldflags "-static"' .

Run

./dns-exporter --config example.yaml --listen :8080 --timeout 1s --workers 5

Configuration

The exporter requires a YAML configuration file specifying the DNS queries:

domains:
  - domain: "example.com"
    record_type: "A"
  - domain: "example.org"
    record_type: "MX"
  - domain: "google.com"
    record_type: "CNAME"
dns_server: "127.0.0.1:53"

Prometheus Metrics

The exporter exposes the following metrics at /metrics:

Metric	Description
dnsexp_dns_query_time_seconds	Time taken for the DNS query (seconds)
dnsexp_dns_query_success	1 if query was successful, 0 otherwise
dnsexp_dns_last_check_timestamp	Timestamp of the last DNS query attempt

Example Prometheus Configuration

Add the following job to your prometheus.yml:

scrape_configs:
  - job_name: 'dns_exporter'
    static_configs:
      - targets: ['localhost:8080']

License

MIT License

Author

Denys Lemeshko - GitHub