chore: add CLI invokation telemetry (#7589)

coderd/httpmw/clitelemetry.go

@@ -0,0 +1,80 @@
+package httpmw
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"net/http"
+	"sync"
+	"time"
+
+	"tailscale.com/tstime/rate"
+
+	"cdr.dev/slog"
+	"github.com/coder/coder/coderd/telemetry"
+	"github.com/coder/coder/codersdk"
+)
+
+func ReportCLITelemetry(log slog.Logger, rep telemetry.Reporter) func(http.Handler) http.Handler {
+	var (
+		mu sync.Mutex
+
+		// We send telemetry at most once per minute.
+		limiter = rate.NewLimiter(rate.Every(time.Minute), 1)
+		queue   []telemetry.CLIInvocation
+	)
+
+	log = log.Named("cli-telemetry")
+
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+			// No matter what, we proceed with the request.
+			defer next.ServeHTTP(rw, r)
+
+			payload := r.Header.Get(codersdk.CLITelemetryHeader)
+			if payload == "" {
+				return
+			}
+
+			byt, err := base64.StdEncoding.DecodeString(payload)
+			if err != nil {
+				log.Error(
+					r.Context(),
+					"base64 decode",
+					slog.F("error", err),
+				)
+				return
+			}
+
+			var inv telemetry.CLIInvocation
+			err = json.Unmarshal(byt, &inv)
+			if err != nil {
+				log.Error(
+					r.Context(),
+					"unmarshal header",
+					slog.Error(err),
+				)
+				return
+			}
+
+			// We do expensive work in a goroutine so we don't block the
+			// request.
+			go func() {
+				mu.Lock()
+				defer mu.Unlock()
+
+				queue = append(queue, inv)
+				if !limiter.Allow() && len(queue) < 1024 {
+					return
+				}
+				rep.Report(&telemetry.Snapshot{
+					CLIInvocations: queue,
+				})
+				log.Debug(
+					r.Context(),
+					"report sent", slog.F("count", len(queue)),
+				)
+				queue = queue[:0]
+			}()
+		})
+	}
+}