zero: resource bundle reconciler (#4445)

internal/zero/reconciler/service.go

@@ -0,0 +1,89 @@
+package reconciler
+
+/*
+ * This is a main control loop for the reconciler service.
+ *
+ */
+
+import (
+	"context"
+	"time"
+
+	"golang.org/x/sync/errgroup"
+	"golang.org/x/time/rate"
+
+	"github.com/pomerium/pomerium/internal/atomicutil"
+	connect_mux "github.com/pomerium/zero-sdk/connect-mux"
+)
+
+type service struct {
+	config *reconcilerConfig
+
+	databrokerRateLimit *rate.Limiter
+
+	bundles BundleQueue
+
+	fullSyncRequest        chan struct{}
+	bundleSyncRequest      chan struct{}
+	periodicUpdateInterval atomicutil.Value[time.Duration]
+}
+
+// Run creates a new bundle updater client
+// that runs until the context is canceled or a fatal error occurs.
+func Run(ctx context.Context, opts ...Option) error {
+	config := newConfig(opts...)
+
+	c := &service{
+		config:              config,
+		databrokerRateLimit: rate.NewLimiter(rate.Limit(config.databrokerRPS), 1),
+		fullSyncRequest:     make(chan struct{}, 1),
+	}
+	c.periodicUpdateInterval.Store(config.checkForUpdateIntervalWhenDisconnected)
+
+	eg, ctx := errgroup.WithContext(ctx)
+	eg.Go(func() error { return c.watchUpdates(ctx) })
+	eg.Go(func() error { return c.SyncLoop(ctx) })
+
+	return eg.Wait()
+}
+
+// run is a main control loop.
+// it is very simple and sequential download and reconcile.
+// it may be later optimized by splitting between download and reconciliation process,
+// as we would get more resource bundles beyond the config.
+func (c *service) watchUpdates(ctx context.Context) error {
+	return c.config.api.Watch(ctx,
+		connect_mux.WithOnConnected(func(ctx context.Context) {
+			c.triggerFullUpdate(true)
+		}),
+		connect_mux.WithOnDisconnected(func(_ context.Context) {
+			c.triggerFullUpdate(false)
+		}),
+		connect_mux.WithOnBundleUpdated(func(_ context.Context, key string) {
+			c.triggerBundleUpdate(key)
+		}),
+	)
+}
+
+func (c *service) triggerBundleUpdate(id string) {
+	c.periodicUpdateInterval.Store(c.config.checkForUpdateIntervalWhenConnected)
+	c.bundles.MarkForSync(id)
+
+	select {
+	case c.fullSyncRequest <- struct{}{}:
+	default:
+	}
+}
+
+func (c *service) triggerFullUpdate(connected bool) {
+	timeout := c.config.checkForUpdateIntervalWhenDisconnected
+	if connected {
+		timeout = c.config.checkForUpdateIntervalWhenConnected
+	}
+	c.periodicUpdateInterval.Store(timeout)
+
+	select {
+	case c.fullSyncRequest <- struct{}{}:
+	default:
+	}
+}