initial checkin

.gitignore

@@ -0,0 +1 @@
+ctlog-uptime-exporter

LICENSE

@@ -0,0 +1,188 @@
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+   See the License for the specific language governing permissions and
+   limitations under the License.

README.md

@@ -0,0 +1,52 @@
+# ctlog-uptime-exporter
+
+A Prometheus exporter for [Certificate Transparency](https://certificate.transparency.dev/) 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
+
+```sh
+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
+
+```yaml
+scrape_configs:
+  - job_name: ctlog_uptime
+    static_configs:
+      - targets: ['localhost:9781']
+```
+
+## License
+
+Apache 2.0 — see [LICENSE](LICENSE).

go.mod

@@ -0,0 +1,16 @@
+module git.ipng.ch/certificate-transparency/ctlog-uptime-exporter
+
+go 1.24.6
+
+require (
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/prometheus/client_golang v1.23.2 // indirect
+	github.com/prometheus/client_model v0.6.2 // indirect
+	github.com/prometheus/common v0.66.1 // indirect
+	github.com/prometheus/procfs v0.16.1 // indirect
+	go.yaml.in/yaml/v2 v2.4.2 // indirect
+	golang.org/x/sys v0.35.0 // indirect
+	google.golang.org/protobuf v1.36.8 // indirect
+)

go.sum

@@ -0,0 +1,21 @@
+github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
+github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
+github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
+github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
+github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
+github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
+github.com/prometheus/client_golang v1.23.2 h1:Je96obch5RDVy3FDMndoUsjAhG5Edi49h0RJWRi/o0o=
+github.com/prometheus/client_golang v1.23.2/go.mod h1:Tb1a6LWHB3/SPIzCoaDXI4I8UHKeFTEQ1YCr+0Gyqmg=
+github.com/prometheus/client_model v0.6.2 h1:oBsgwpGs7iVziMvrGhE53c/GrLUsZdHnqNwqPLxwZyk=
+github.com/prometheus/client_model v0.6.2/go.mod h1:y3m2F6Gdpfy6Ut/GBsUqTWZqCUvMVzSfMLjcu6wAwpE=
+github.com/prometheus/common v0.66.1 h1:h5E0h5/Y8niHc5DlaLlWLArTQI7tMrsfQjHV+d9ZoGs=
+github.com/prometheus/common v0.66.1/go.mod h1:gcaUsgf3KfRSwHY4dIMXLPV0K/Wg1oZ8+SbZk/HH/dA=
+github.com/prometheus/procfs v0.16.1 h1:hZ15bTNuirocR6u0JZ6BAHHmwS1p8B4P6MRqxtzMyRg=
+github.com/prometheus/procfs v0.16.1/go.mod h1:teAbpZRB1iIAJYREa1LsoWUXykVXA1KlTmWl8x/U+Is=
+go.yaml.in/yaml/v2 v2.4.2 h1:DzmwEr2rDGHl7lsFgAHxmNz/1NlQ7xLIrlN2h5d1eGI=
+go.yaml.in/yaml/v2 v2.4.2/go.mod h1:081UH+NErpNdqlCXm3TtEran0rJZGxAYx9hb/ELlsPU=
+golang.org/x/sys v0.35.0 h1:vz1N37gP5bs89s7He8XuIYXpyY0+QlsKmzipCbUtyxI=
+golang.org/x/sys v0.35.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
+google.golang.org/protobuf v1.36.8 h1:xHScyCOEuuwZEc6UtSOvPbAT4zRh0xcNRYekJwfqyMc=
+google.golang.org/protobuf v1.36.8/go.mod h1:fuxRtAxBytpl4zzqUh6/eyUujkJdNiuEkXntxiD/uRU=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=

main.go

@@ -0,0 +1,136 @@
+package main
+
+import (
+	"encoding/csv"
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	"math/rand"
+	"net/http"
+	"strconv"
+	"sync"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+
+type exporter struct {
+	mu      sync.RWMutex
+	uptime  *prometheus.GaugeVec
+	fetchOk prometheus.Gauge
+	fetchAt prometheus.Gauge
+}
+
+func newExporter(reg prometheus.Registerer) *exporter {
+	e := &exporter{
+		uptime: prometheus.NewGaugeVec(prometheus.GaugeOpts{
+			Name: "ct_log_uptime_ratio",
+			Help: "24h uptime ratio (0–1) for a CT log endpoint, sourced from gstatic.com.",
+		}, []string{"log_url", "endpoint"}),
+		fetchOk: prometheus.NewGauge(prometheus.GaugeOpts{
+			Name: "ct_log_uptime_fetch_success",
+			Help: "1 if the last CSV fetch succeeded, 0 otherwise.",
+		}),
+		fetchAt: prometheus.NewGauge(prometheus.GaugeOpts{
+			Name: "ct_log_uptime_fetch_timestamp_seconds",
+			Help: "Unix timestamp of the last CSV fetch attempt.",
+		}),
+	}
+	reg.MustRegister(e.uptime, e.fetchOk, e.fetchAt)
+	return e
+}
+
+func (e *exporter) fetch(csvURL string) error {
+	resp, err := http.Get(csvURL)
+	if err != nil {
+		return fmt.Errorf("GET %s: %w", csvURL, err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("unexpected status %s", resp.Status)
+	}
+
+	r := csv.NewReader(resp.Body)
+	// skip header
+	if _, err := r.Read(); err != nil {
+		return fmt.Errorf("read header: %w", err)
+	}
+
+	// collect new values before updating metrics
+	type row struct{ logURL, endpoint string; ratio float64 }
+	var rows []row
+	for {
+		rec, err := r.Read()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return fmt.Errorf("read row: %w", err)
+		}
+		if len(rec) < 3 {
+			continue
+		}
+		pct, err := strconv.ParseFloat(rec[2], 64)
+		if err != nil {
+			log.Printf("skipping row with unparseable uptime %q: %v", rec[2], err)
+			continue
+		}
+		rows = append(rows, row{rec[0], rec[1], pct / 100.0})
+	}
+
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	e.uptime.Reset()
+	for _, row := range rows {
+		e.uptime.WithLabelValues(row.logURL, row.endpoint).Set(row.ratio)
+	}
+	return nil
+}
+
+func (e *exporter) run(csvURL string, interval, jitter time.Duration) {
+	do := func() {
+		e.fetchAt.SetToCurrentTime()
+		if err := e.fetch(csvURL); err != nil {
+			log.Printf("fetch error: %v", err)
+			e.fetchOk.Set(0)
+		} else {
+			log.Printf("fetch ok")
+			e.fetchOk.Set(1)
+		}
+	}
+
+	do()
+	for {
+		delta := time.Duration(rand.Int63n(int64(2*jitter))) - jitter
+		sleep := interval + delta
+		log.Printf("next fetch in %s", sleep.Round(time.Second))
+		time.Sleep(sleep)
+		do()
+	}
+}
+
+func main() {
+	addr     := flag.String("listen",   ":9781",                                                     "address to listen on")
+	csvURL   := flag.String("url",      "https://www.gstatic.com/ct/compliance/endpoint_uptime_24h.csv", "URL of the uptime CSV")
+	interval := flag.Duration("interval", 12*time.Hour,  "how often to fetch the CSV")
+	jitter   := flag.Duration("jitter",    5*time.Minute, "maximum ±jitter applied to the fetch interval")
+	flag.Parse()
+
+	reg := prometheus.NewRegistry()
+	reg.MustRegister(prometheus.NewProcessCollector(prometheus.ProcessCollectorOpts{}))
+	reg.MustRegister(prometheus.NewGoCollector())
+
+	exp := newExporter(reg)
+	go exp.run(*csvURL, *interval, *jitter)
+
+	http.Handle("/metrics", promhttp.HandlerFor(reg, promhttp.HandlerOpts{}))
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintf(w, `<html><body><a href="/metrics">metrics</a></body></html>`)
+	})
+
+	log.Printf("listening on %s", *addr)
+	log.Fatal(http.ListenAndServe(*addr, nil))
+}