zero: bootstrap config (#4444)

internal/zero/bootstrap/source.go

@@ -0,0 +1,93 @@
+package bootstrap
+
+import (
+	"context"
+	"sync"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
+
+	"github.com/pomerium/pomerium/config"
+	"github.com/pomerium/pomerium/internal/atomicutil"
+	cluster_api "github.com/pomerium/zero-sdk/cluster"
+)
+
+var (
+	_ = config.Source(new(source))
+)
+
+var (
+	cmpOpts = []cmp.Option{
+		cmpopts.IgnoreUnexported(config.Options{}),
+		cmpopts.EquateEmpty(),
+	}
+)
+
+type source struct {
+	cfg atomicutil.Value[*config.Config]
+
+	listenerLock sync.RWMutex
+	listeners    []config.ChangeListener
+
+	ready     chan struct{}
+	markReady sync.Once
+}
+
+func (src *source) WaitReady(ctx context.Context) error {
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case <-src.ready:
+		return nil
+	}
+}
+
+// GetConfig implements config.Source
+func (src *source) GetConfig() *config.Config {
+	return src.cfg.Load()
+}
+
+// OnConfigChange implements config.Source
+func (src *source) OnConfigChange(_ context.Context, l config.ChangeListener) {
+	src.listenerLock.Lock()
+	src.listeners = append(src.listeners, l)
+	src.listenerLock.Unlock()
+}
+
+// UpdateBootstrap updates the underlying configuration options
+func (src *source) UpdateBootstrap(ctx context.Context, cfg cluster_api.BootstrapConfig) bool {
+	current := src.cfg.Load()
+	incoming := current.Clone()
+	applyBootstrapConfig(incoming.Options, &cfg)
+
+	src.markReady.Do(func() { close(src.ready) })
+
+	if cmp.Equal(incoming.Options, current.Options, cmpOpts...) {
+		return false
+	}
+
+	src.cfg.Store(incoming)
+
+	src.notifyListeners(ctx, incoming)
+
+	return true
+}
+
+// notifyListeners notifies all listeners of a configuration change
+func (src *source) notifyListeners(ctx context.Context, cfg *config.Config) {
+	src.listenerLock.RLock()
+	listeners := make([]config.ChangeListener, len(src.listeners))
+	copy(listeners, src.listeners)
+	src.listenerLock.RUnlock()
+
+	for _, l := range listeners {
+		l(ctx, cfg)
+	}
+}
+
+func applyBootstrapConfig(dst *config.Options, src *cluster_api.BootstrapConfig) {
+	if src.DatabrokerStorageConnection != nil {
+		dst.DataBrokerStorageType = "postgres"
+		dst.DataBrokerStorageConnectionString = *src.DatabrokerStorageConnection
+	}
+}