zero/telemetry: calculate DAU and MAU (#4810)

internal/zero/analytics/collector.go

@@ -0,0 +1,131 @@
+// Package analytics collects active user metrics and reports them to the cloud dashboard
+package analytics
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/pomerium/pomerium/internal/log"
+	"github.com/pomerium/pomerium/pkg/grpc/databroker"
+)
+
+// Collect collects metrics and reports them to the cloud
+func Collect(
+	ctx context.Context,
+	client databroker.DataBrokerServiceClient,
+	updateInterval time.Duration,
+) error {
+	c := &collector{
+		client:         client,
+		counters:       make(map[string]*ActiveUsersCounter),
+		updateInterval: updateInterval,
+	}
+
+	leaser := databroker.NewLeaser("pomerium-zero-analytics", c.leaseTTL(), c)
+	return leaser.Run(ctx)
+}
+
+type collector struct {
+	client         databroker.DataBrokerServiceClient
+	counters       map[string]*ActiveUsersCounter
+	updateInterval time.Duration
+}
+
+func (c *collector) RunLeased(ctx context.Context) error {
+	err := c.loadCounters(ctx)
+	if err != nil {
+		return fmt.Errorf("failed to load counters: %w", err)
+	}
+
+	err = c.runPeriodicUpdate(ctx)
+	if err != nil {
+		return fmt.Errorf("failed to run periodic update: %w", err)
+	}
+
+	return nil
+}
+
+func (c *collector) GetDataBrokerServiceClient() databroker.DataBrokerServiceClient {
+	return c.client
+}
+
+func (c *collector) loadCounters(ctx context.Context) error {
+	now := time.Now()
+	for key, resetFn := range map[string]IntervalResetFunc{
+		"mau": ResetMonthlyUTC,
+		"dau": ResetDailyUTC,
+	} {
+		state, err := LoadMetricState(ctx, c.client, key)
+		if err != nil && !databroker.IsNotFound(err) {
+			return err
+		}
+		if state == nil {
+			c.counters[key] = NewActiveUsersCounter(resetFn, now)
+			continue
+		}
+
+		counter, err := LoadActiveUsersCounter(state.Data, state.LastReset, resetFn)
+		if err != nil {
+			log.Ctx(ctx).Error().Err(err).Str("metric", key).Msg("failed to load metric state, resetting")
+			counter = NewActiveUsersCounter(resetFn, now)
+		}
+		c.counters[key] = counter
+	}
+
+	return nil
+}
+
+func (c *collector) runPeriodicUpdate(ctx context.Context) error {
+	ticker := time.NewTicker(c.updateInterval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return nil
+		case <-ticker.C:
+			if err := c.update(ctx); err != nil {
+				return err
+			}
+		}
+	}
+}
+
+func (c *collector) update(ctx context.Context) error {
+	users, err := CurrentUsers(ctx, c.client)
+	if err != nil {
+		return fmt.Errorf("failed to get current users: %w", err)
+	}
+
+	now := time.Now()
+	for key, counter := range c.counters {
+		before := counter.Count()
+		after, _ := counter.Update(users, now)
+		if before == after {
+			log.Ctx(ctx).Debug().Msgf("metric %s not changed: %d", key, counter.Count())
+			continue
+		}
+		log.Ctx(ctx).Debug().Msgf("metric %s updated: %d", key, counter.Count())
+
+		data, err := counter.ToBinary()
+		if err != nil {
+			return fmt.Errorf("failed to marshal metric %s: %w", key, err)
+		}
+
+		err = SaveMetricState(ctx, c.client, key, data, after, counter.GetLastReset())
+		if err != nil {
+			return fmt.Errorf("failed to save metric %s: %w", key, err)
+		}
+	}
+
+	return nil
+}
+
+func (c *collector) leaseTTL() time.Duration {
+	const defaultTTL = time.Minute * 5
+	if defaultTTL < c.updateInterval {
+		return defaultTTL
+	}
+	return c.updateInterval
+}