Add a demo host-metrics fixture

Pushes synthetic cairnobs.metrics/cairnobs.heartbeat-tagged records
straight to ingest so a demo deployment's Hosts page and per-host detail
page have CPU/memory/disk to show. Neither benchmark-fixture nor
windows-fixture emits those two attributes -- only the real agent does
-- so nothing else could populate that page.

Superseded by /hack/demo-simulator in the next commit, which covers the
same records as part of a whole fleet; kept because it is still the
smallest thing that fills the Hosts page on its own.
This commit is contained in:
2026-08-22 16:12:35 -07:00
parent 754996dbfd
commit e6a58f58ea
3 changed files with 233 additions and 0 deletions
+177
View File
@@ -0,0 +1,177 @@
// Command demo-hosts-fixture pushes synthetic cairnobs.metrics/
// cairnobs.heartbeat-tagged LogRecords directly to ingest's gRPC
// endpoint, one snapshot every -interval across -time-spread per
// synthetic host, so a demo deployment's Hosts page and per-host detail
// page (CPU/mem/disk charts) have something to show. Neither
// /hack/benchmark-fixture nor /hack/windows-fixture emit these two
// attributes -- only the real agent does
// (agent/cairnobs-agent/src/main.rs's send_metrics/send_heartbeat) --
// so this fills that gap for demo/exploration data specifically, the
// same use case benchmark-fixture's -time-spread flag was already added
// for.
package main
import (
"context"
"crypto/tls"
"crypto/x509"
"flag"
"fmt"
"math/rand"
"os"
"strconv"
"time"
"google.golang.org/grpc"
"google.golang.org/grpc/credentials"
logsv1 "github.com/cairnobs/cairnobs/proto/sentry/logs/v1"
)
// Mirrors hack/benchmark-fixture's host/service pools so the same
// hosts show up consistently across both the raw log fixture and this
// one -- a viewer clicking from a host's log lines to its metrics page
// (or vice versa) sees the same host, not a disjoint set.
var (
hosts = []string{"host-01", "host-02", "host-03", "host-04", "host-05", "host-06", "host-07", "host-08"}
hostServices = map[string]string{
"host-01": "api", "host-02": "api", "host-03": "web", "host-04": "web",
"host-05": "worker", "host-06": "worker", "host-07": "db", "host-08": "auth",
}
osNames = []string{"Ubuntu 24.04.1 LTS", "Debian GNU/Linux 13 (trixie)", "Ubuntu 22.04.5 LTS"}
kernelVersions = []string{"6.8.0-45-generic", "6.1.0-25-amd64", "5.15.0-118-generic"}
)
func main() {
addr := flag.String("addr", "localhost:4317", "ingest gRPC address")
caFile := flag.String("ca", "../dev-certs/out/ca.pem", "CA cert path")
certFile := flag.String("cert", "../dev-certs/out/client.pem", "client cert path")
keyFile := flag.String("key", "../dev-certs/out/client-key.pem", "client key path")
timeSpread := flag.Duration("time-spread", 24*time.Hour, "spread metrics snapshots uniformly across [now-spread, now], one per interval per host")
interval := flag.Duration("interval", 5*time.Minute, "spacing between synthetic metrics snapshots per host")
flag.Parse()
tlsConf, err := loadTLSConfig(*caFile, *certFile, *keyFile)
if err != nil {
fmt.Fprintln(os.Stderr, "loading TLS config:", err)
os.Exit(1)
}
conn, err := grpc.NewClient(*addr, grpc.WithTransportCredentials(credentials.NewTLS(tlsConf)))
if err != nil {
fmt.Fprintln(os.Stderr, "dialing ingest:", err)
os.Exit(1)
}
defer conn.Close()
client := logsv1.NewLogIngestClient(conn)
now := time.Now()
var records []*logsv1.LogRecord
for _, host := range hosts {
service := hostServices[host]
osName := osNames[rand.Intn(len(osNames))]
kernel := kernelVersions[rand.Intn(len(kernelVersions))]
cores := []int{2, 4, 8, 16}[rand.Intn(4)]
memTotal := []int64{4, 8, 16, 32}[rand.Intn(4)] * 1024 * 1024 * 1024
diskTotal := []int64{50, 100, 250, 500}[rand.Intn(4)] * 1024 * 1024 * 1024
// A gently drifting baseline per host so the charts show real
// variation instead of flat noise -- CPU/mem wander within a
// plausible band across the snapshot window.
cpuBase := 5 + rand.Float64()*40
memBase := 0.3 + rand.Float64()*0.4
diskBase := 0.2 + rand.Float64()*0.5
uptime := int64(*timeSpread/time.Second) + rand.Int63n(30*86400)
for t := now.Add(-*timeSpread); t.Before(now); t = t.Add(*interval) {
cpuPercent := clamp(cpuBase+rand.NormFloat64()*8, 0.5, 98)
memUsed := int64(float64(memTotal) * clamp(memBase+rand.NormFloat64()*0.05, 0.05, 0.95))
diskUsed := int64(float64(diskTotal) * clamp(diskBase+rand.NormFloat64()*0.02, 0.05, 0.9))
records = append(records, &logsv1.LogRecord{
TimestampUnixNano: t.UnixNano(),
Host: host,
Service: service,
Severity: logsv1.Severity_SEVERITY_INFO,
Message: "host metrics",
Attributes: map[string]string{
"cairnobs.metrics": "true",
"cpu_percent": fmt.Sprintf("%.2f", cpuPercent),
"mem_used_bytes": strconv.FormatInt(memUsed, 10),
"mem_total_bytes": strconv.FormatInt(memTotal, 10),
"disk_used_bytes": strconv.FormatInt(diskUsed, 10),
"disk_total_bytes": strconv.FormatInt(diskTotal, 10),
"cpu_cores": strconv.Itoa(cores),
"os_name": osName,
"kernel_version": kernel,
"arch": "x86_64",
"uptime_seconds": strconv.FormatInt(uptime-int64(now.Sub(t).Seconds()), 10),
"ipv4_addresses": fmt.Sprintf("10.0.0.%d", 10+rand.Intn(240)),
"ipv6_addresses": "",
},
})
records = append(records, &logsv1.LogRecord{
TimestampUnixNano: t.UnixNano(),
Host: host,
Service: service,
Severity: logsv1.Severity_SEVERITY_INFO,
Message: "agent heartbeat",
Attributes: map[string]string{"cairnobs.heartbeat": "true"},
})
}
}
fmt.Printf("pushing %d synthetic host-metrics/heartbeat records for %d hosts...\n", len(records), len(hosts))
const batchSize = 500
for offset := 0; offset < len(records); offset += batchSize {
end := offset + batchSize
if end > len(records) {
end = len(records)
}
ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
resp, err := client.PushBatch(ctx, &logsv1.PushBatchRequest{
BatchId: fmt.Sprintf("demo-hosts-%d", offset),
Records: records[offset:end],
})
cancel()
if err != nil {
fmt.Fprintf(os.Stderr, "PushBatch at offset %d failed: %v\n", offset, err)
os.Exit(1)
}
fmt.Printf("sent %d/%d (accepted %d)\n", end, len(records), resp.GetAccepted())
}
fmt.Println("done")
}
func clamp(v, lo, hi float64) float64 {
if v < lo {
return lo
}
if v > hi {
return hi
}
return v
}
func loadTLSConfig(caFile, certFile, keyFile string) (*tls.Config, error) {
caPEM, err := os.ReadFile(caFile)
if err != nil {
return nil, fmt.Errorf("reading CA cert %s: %w", caFile, err)
}
caPool := x509.NewCertPool()
if !caPool.AppendCertsFromPEM(caPEM) {
return nil, fmt.Errorf("no valid certificates found in %s", caFile)
}
cert, err := tls.LoadX509KeyPair(certFile, keyFile)
if err != nil {
return nil, fmt.Errorf("loading client cert/key: %w", err)
}
return &tls.Config{
RootCAs: caPool,
Certificates: []tls.Certificate{cert},
}, nil
}