feat: add custom announce addresses support for Kubernetes deployments

Author: ordishs

.gitignore

@@ -1,2 +1,3 @@
+.history/
 p2p_poc
 peer_cache.json

Makefile

@@ -0,0 +1,21 @@
+.PHONY: lint test build clean
+
+lint:
+	@echo "Running linters..."
+	@go vet ./...
+	@gofmt -l -s .
+	@if command -v golangci-lint >/dev/null 2>&1; then \
+		golangci-lint run ./...; \
+	else \
+		echo "golangci-lint not installed, skipping"; \
+		echo "Install with: brew install golangci-lint"; \
+	fi
+
+test:
+	@echo "Running tests..."
+	@go test -v -race -coverprofile=coverage.out ./...
+	@go tool cover -func=coverage.out
+
+clean:
+	@echo "Cleaning..."
+	@rm -f p2p_poc example/example coverage.out

README.md

@@ -82,6 +82,7 @@ type Config struct {
     Logger         Logger         // Optional: custom logger (uses DefaultLogger if not provided)
     PrivateKey     crypto.PrivKey // Required: private key for persistent peer ID
     PeerCacheFile  string         // Optional: file path for peer persistence
+    AnnounceAddrs  []string       // Optional: addresses to advertise to peers (for K8s)
 }
 ```
 
@@ -143,6 +144,31 @@ When enabled:
 - This significantly speeds up network reconnection
 - If not provided, peer caching is disabled
 
+**Kubernetes Support:**
+
+The `AnnounceAddrs` field allows you to specify the external addresses that your peer should advertise. This is essential in Kubernetes where the pod's internal IP differs from the externally accessible address:
+
+```go
+// Get external address from environment or K8s service
+externalIP := os.Getenv("EXTERNAL_IP")      // e.g., "203.0.113.1"
+externalPort := os.Getenv("EXTERNAL_PORT")  // e.g., "30001"
+
+client, err := p2p.NewPeer(p2p.Config{
+    Name:       "node1",
+    PrivateKey: privKey,
+    AnnounceAddrs: []string{
+        fmt.Sprintf("/ip4/%s/tcp/%s", externalIP, externalPort),
+    },
+})
+```
+
+Common Kubernetes scenarios:
+- **LoadBalancer Service**: Use the external IP of the LoadBalancer
+- **NodePort Service**: Use the node's external IP and the NodePort
+- **Ingress with TCP**: Use the ingress external IP and configured port
+
+Without `AnnounceAddrs`, libp2p will announce the pod's internal IP, which won't be reachable from outside the cluster.
+
 ### Client
 
 #### GeneratePrivateKeyHex

client.go

@@ -64,6 +64,24 @@ func NewClient(config Config) (*Client, error) {
 	var hostOpts []libp2p.Option
 	hostOpts = append(hostOpts, libp2p.Identity(config.PrivateKey))
 
+	// Configure announce addresses if provided (useful for K8s)
+	if len(config.AnnounceAddrs) > 0 {
+		var announceAddrs []multiaddr.Multiaddr
+		for _, addrStr := range config.AnnounceAddrs {
+			maddr, err := multiaddr.NewMultiaddr(addrStr)
+			if err != nil {
+				cancel()
+				return nil, fmt.Errorf("invalid announce address %s: %w", addrStr, err)
+			}
+			announceAddrs = append(announceAddrs, maddr)
+		}
+
+		hostOpts = append(hostOpts, libp2p.AddrsFactory(func([]multiaddr.Multiaddr) []multiaddr.Multiaddr {
+			return announceAddrs
+		}))
+		logger.Infof("Using custom announce addresses: %v", config.AnnounceAddrs)
+	}
+
 	// Create libp2p host
 	hostOpts = append(hostOpts,
 		libp2p.ListenAddrStrings(

config.go

@@ -46,4 +46,11 @@ type Config struct {
 	// If provided, the client will save connected peers to this file and reload them
 	// on restart for faster reconnection. If not provided, peer caching is disabled.
 	PeerCacheFile string
+
+	// AnnounceAddrs is an optional list of multiaddr strings that this peer should
+	// advertise to other peers. This is useful in Kubernetes or other environments
+	// where the local address differs from the externally reachable address.
+	// Example: []string{"/ip4/203.0.113.1/tcp/4001"}
+	// If not provided, libp2p will automatically detect and announce local addresses.
+	AnnounceAddrs []string
 }