subscribe to container changes in Caddyfile controller

internal/machine/caddyfile/controller.go

@@ -3,9 +3,11 @@ package caddyfile
 import (
 	"context"
 	"fmt"
+	"log/slog"
 	"os"
 	"path/filepath"
 	"sync"
+	"uncloud/internal/api"
 	"uncloud/internal/machine/store"
 )
 
@@ -30,6 +32,62 @@ func NewController(store *store.Store, path string) (*Controller, error) {
 	}, nil
 }
 
-func (cc *Controller) Run(ctx context.Context) error {
+func (c *Controller) Run(ctx context.Context) error {
+	containerRecords, changes, err := c.store.SubscribeContainers(ctx)
+	if err != nil {
+		return fmt.Errorf("subscribe to container changes: %w", err)
+	}
+	slog.Info("Subscribed to container changes in the cluster to generate Caddy configuration.")
+
+	containers, err := c.filterAvailableContainers(containerRecords)
+	if err != nil {
+		return fmt.Errorf("filter available containers: %w", err)
+	}
+	if err = c.generateConfig(containers); err != nil {
+		return fmt.Errorf("generate Caddy configuration: %w", err)
+	}
+
+	for {
+		select {
+		case _, ok := <-changes:
+			if !ok {
+				return fmt.Errorf("containers subscription failed")
+			}
+			slog.Debug("Cluster containers changed, updating Caddy configuration.")
+
+			containerRecords, err = c.store.ListContainers(ctx, store.ListOptions{})
+			if err != nil {
+				slog.Error("Failed to list containers.", "err", err)
+				continue
+			}
+			containers, err = c.filterAvailableContainers(containerRecords)
+			if err != nil {
+				slog.Error("Failed to filter available containers.", "err", err)
+				continue
+			}
+			if err = c.generateConfig(containers); err != nil {
+				slog.Error("Failed to generate Caddy configuration.", "err", err)
+			}
+
+			slog.Debug("Updated Caddy configuration.", "path", c.path)
+		case <-ctx.Done():
+			return nil
+		}
+	}
+}
+
+// filterAvailableContainers filters out containers that are likely unavailable from this machine. The availability
+// is determined by the cluster membership state of the machine that the container is running on.
+// TODO: implement machine membership check using Corrossion Admin client.
+func (c *Controller) filterAvailableContainers(containerRecords []*store.ContainerRecord) ([]*api.Container, error) {
+	containers := make([]*api.Container, len(containerRecords))
+	for i, cr := range containerRecords {
+		containers[i] = cr.Container
+	}
+	return containers, nil
+}
+
+func (c *Controller) generateConfig(containers []*api.Container) error {
+	// TODO
 	return nil
 }