prom2pushgateway

A lightweight Go service that periodically scrapes metrics from an HTTP endpoint and pushes them to a Prometheus Pushgateway.

Supports:

• HTTP(S) targets
• Basic Authentication for Pushgateway
• Custom metric injection
• Config via environment variables only
• Configurable timeouts for both scraping and pushing

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🧱 Environment Variables

Variable	Description	Default
SOURCE_URL	URL of the source metrics endpoint to scrape	http://app:8080/metrics
PUSHGATEWAY_URL	URL of the target Pushgateway endpoint (e.g. http://pushgateway:9091/metrics/job/example)	http://pushgateway:9091/metrics/job/example
PUSHGATEWAY_USER	Optional username for HTTP Basic Auth	(empty)
PUSHGATEWAY_PASS	Optional password for HTTP Basic Auth	(empty)
INTERVAL	Scrape and push interval in seconds	15
SCRAPE_TIMEOUT	Timeout for scraping operation (seconds)	5
PUSH_TIMEOUT	Timeout for pushing to Pushgateway (seconds)	5
CUSTOM_METRICS_FILE	Optional path to file metric for join data on every push	/etc/custom-metrics.txt

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🧩 Example: Docker Compose

version: "3.8"

services:
  app:
    image: prom/prometheus-example-app
    ports:
      - "8080:8080"

  pushgateway:
    image: prom/pushgateway
    ports:
      - "9091:9091"

  scraper:
    build: .
    environment:
      SOURCE_URL: "http://app:8080/metrics"
      PUSHGATEWAY_URL: "http://pushgateway:9091/metrics/job/example"
      INTERVAL: "10"
      SCRAPE_TIMEOUT: "3"
      PUSH_TIMEOUT: "3"

---

🔧 Build

go mod init scraper
go mod tidy
go build -o scraper .

or via Docker:

docker build -t scraper:latest .

---

🚀 Run

docker run --rm \
  -e SOURCE_URL=http://app:8080/metrics \
  -e PUSHGATEWAY_URL=http://user:pass@pushgateway:9091/metrics/job/test \
  -e INTERVAL=10 \
  -e SCRAPE_TIMEOUT=3 \
  -e PUSH_TIMEOUT=3 \
  scraper:latest

---

🪶 Logs Example

[2025-11-03T15:22:11Z] pushed → http://pushgateway:9091/metrics/job/example (auth=true custom=my_custom_value=42.5)

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⚙️ Notes

• Basic Auth credentials can be set via URL or environment variables.
• Both HTTPS and plain HTTP are supported.
• On each cycle:
  1. The app scrapes metrics from SOURCE_URL
  2. Optionally adds a custom metric line
  3. Pushes the result to PUSHGATEWAY_URL
• Logs are printed to stdout only.

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📜 License

GNU GENERAL PUBLIC LICENSE