command-exporter

A lightweight Prometheus exporter that runs shell commands at fixed intervals and exposes their numeric output as metrics.

Features

• Executes arbitrary shell commands
• Parses stdout for float values
• Exposes metrics with command, exit_code, stdout_summary, stderr_summary labels
• Logs full execution details
• Configurable interval and output summary truncation

Configuration

Create a config.yaml file:

commands:
  - name: process_count
    command: ["bash", "-c", "ps aux | wc -l"]
    interval: "10s"
    stdout_limit: 50

  - name: load_avg
    command: ["bash", "-c", "cat /proc/loadavg | awk '{print $1}'"]
    interval: "5s"
    stdout_limit: 40

Running

go build -o command-exporter ./cmd/command-exporter
./command-exporter

Exporter listens by default on :9860.

Prometheus Scrape Config

Add this to your prometheus.yml:

scrape_configs:
  - job_name: 'command-exporter'
    static_configs:
      - targets: ['localhost:9860']

Metrics Output

Sample:

# HELP command_result Result of command execution
# TYPE command_result gauge
command_result{command="load_avg", exit_code="0", stdout_summary="0.13", stderr_summary=""} 0.13
command_result{command="process_count", exit_code="0", stdout_summary="142", stderr_summary=""} 142

Docker

FROM golang:1.21-alpine AS builder
WORKDIR /app
COPY . .
RUN go build -o command-exporter ./cmd/command-exporter

FROM alpine:latest
WORKDIR /root/
COPY --from=builder /app/command-exporter .
COPY config.yaml .
EXPOSE 9860
ENTRYPOINT ["./command-exporter"]

Notes

• Only the first float token from stdout is used as the metric value.
• If stdout cannot be parsed to float, command_result will return 1 and log a warning.