ctlog-uptime-exporter

A Prometheus exporter for Certificate Transparency log uptime data published by Google at:

https://www.gstatic.com/ct/compliance/endpoint_uptime_24h.csv

The CSV reports the 24-hour uptime percentage for each CT log URL broken down by operation type (add-chain, get-entries, get-sth, etc.). This exporter fetches that CSV on a configurable schedule and exposes the data as Prometheus metrics.

Metrics

Metric	Labels	Description
`ct_log_uptime_ratio`	`log_url`, `endpoint`	24h uptime as a ratio (0–1)
`ct_log_uptime_fetch_success`	—	1 if the last fetch succeeded, 0 otherwise
`ct_log_uptime_fetch_timestamp_seconds`	—	Unix timestamp of the last fetch attempt

Standard go_* and process_* metrics are also exposed.

Usage

go build -o ctlog-uptime-exporter .
./ctlog-uptime-exporter

Metrics are served at http://localhost:9781/metrics.

Flags

Flag	Default	Description
`-listen`	`:9781`	Address to listen on
`-url`	`https://www.gstatic.com/ct/compliance/endpoint_uptime_24h.csv`	URL of the uptime CSV
`-interval`	`12h`	How often to fetch the CSV
`-jitter`	`5m`	Maximum ±jitter applied to the fetch interval

The exporter fetches the CSV once on startup, then repeats every -interval ± a random value up to -jitter. This avoids thundering-herd effects if multiple instances run in parallel.

Example Prometheus scrape config

scrape_configs:
  - job_name: ctlog_uptime
    static_configs:
      - targets: ['localhost:9781']

License

Apache 2.0 — see LICENSE.

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