agent: support go-discover retry-join for wan

agent/agent.go

@@ -340,8 +340,8 @@ func (a *Agent) Start() error {
 	}
 
 	// start retry join
-	go a.retryJoin()
-	go a.retryJoinWan()
+	go a.retryJoinLAN()
+	go a.retryJoinWAN()
 
 	return nil
 }

agent/retry_join.go

@@ -2,37 +2,88 @@ package agent
 
 import (
 	"fmt"
+	"log"
 	"strings"
 	"time"
 
 	discover "github.com/hashicorp/go-discover"
 )
 
-// RetryJoin is used to handle retrying a join until it succeeds or all
+func (a *Agent) retryJoinLAN() {
+	r := &retryJoiner{
+		cluster:     "LAN",
+		addrs:       a.config.RetryJoin,
+		maxAttempts: a.config.RetryMaxAttempts,
+		interval:    a.config.RetryInterval,
+		join:        a.JoinLAN,
+		logger:      a.logger,
+	}
+	if err := r.retryJoin(); err != nil {
+		a.retryJoinCh <- err
+	}
+}
+
+func (a *Agent) retryJoinWAN() {
+	r := &retryJoiner{
+		cluster:     "WAN",
+		addrs:       a.config.RetryJoinWan,
+		maxAttempts: a.config.RetryMaxAttemptsWan,
+		interval:    a.config.RetryIntervalWan,
+		join:        a.JoinWAN,
+		logger:      a.logger,
+	}
+	if err := r.retryJoin(); err != nil {
+		a.retryJoinCh <- err
+	}
+}
+
+// retryJoiner is used to handle retrying a join until it succeeds or all
 // retries are exhausted.
-func (a *Agent) retryJoin() {
-	cfg := a.config
-	if len(cfg.RetryJoin) == 0 {
-		return
+type retryJoiner struct {
+	// cluster is the name of the serf cluster, e.g. "LAN" or "WAN".
+	cluster string
+
+	// addrs is the list of servers or go-discover configurations
+	// to join with.
+	addrs []string
+
+	// maxAttempts is the number of join attempts before giving up.
+	maxAttempts int
+
+	// interval is the time between two join attempts.
+	interval time.Duration
+
+	// join adds the discovered or configured servers to the given
+	// serf cluster.
+	join func([]string) (int, error)
+
+	// logger is the agent logger. Log messages should contain the
+	// "agent: " prefix.
+	logger *log.Logger
+}
+
+func (r *retryJoiner) retryJoin() error {
+	if len(r.addrs) == 0 {
+		return nil
 	}
 
 	disco := discover.Discover{}
-	a.logger.Printf("[INFO] agent: Retry join is supported for: %s", strings.Join(disco.Names(), " "))
-	a.logger.Printf("[INFO] agent: Joining cluster...")
+	r.logger.Printf("[INFO] agent: Retry join %s is supported for: %s", r.cluster, strings.Join(disco.Names(), " "))
+	r.logger.Printf("[INFO] agent: Joining %s cluster...", r.cluster)
 	attempt := 0
 	for {
 		var addrs []string
 		var err error
 
-		for _, addr := range cfg.RetryJoin {
+		for _, addr := range r.addrs {
 			switch {
 			case strings.Contains(addr, "provider="):
-				servers, err := disco.Addrs(addr, a.logger)
+				servers, err := disco.Addrs(addr, r.logger)
 				if err != nil {
-					a.logger.Printf("[ERR] agent: %s", err)
+					r.logger.Printf("[ERR] agent: Join %s: %s", r.cluster, err)
 				} else {
 					addrs = append(addrs, servers...)
-					a.logger.Printf("[INFO] agent: Discovered servers: %s", strings.Join(servers, " "))
+					r.logger.Printf("[INFO] agent: Discovered %s servers: %s", r.cluster, strings.Join(servers, " "))
 				}
 
 			default:
@@ -41,10 +92,10 @@ func (a *Agent) retryJoin() {
 		}
 
 		if len(addrs) > 0 {
-			n, err := a.JoinLAN(addrs)
+			n, err := r.join(addrs)
 			if err == nil {
-				a.logger.Printf("[INFO] agent: Join completed. Synced with %d initial agents", n)
-				return
+				r.logger.Printf("[INFO] agent: Join %s completed. Synced with %d initial agents", r.cluster, n)
+				return nil
 			}
 		}
 
@@ -53,42 +104,11 @@ func (a *Agent) retryJoin() {
 		}
 
 		attempt++
-		if cfg.RetryMaxAttempts > 0 && attempt > cfg.RetryMaxAttempts {
-			a.retryJoinCh <- fmt.Errorf("agent: max join retry exhausted, exiting")
-			return
+		if r.maxAttempts > 0 && attempt > r.maxAttempts {
+			return fmt.Errorf("agent: max join %s retry exhausted, exiting", r.cluster)
 		}
 
-		a.logger.Printf("[WARN] agent: Join failed: %v, retrying in %v", err, cfg.RetryInterval)
-		time.Sleep(cfg.RetryInterval)
-	}
-}
-
-// RetryJoinWan is used to handle retrying a join -wan until it succeeds or all
-// retries are exhausted.
-func (a *Agent) retryJoinWan() {
-	cfg := a.config
-
-	if len(cfg.RetryJoinWan) == 0 {
-		return
-	}
-
-	a.logger.Printf("[INFO] agent: Joining WAN cluster...")
-
-	attempt := 0
-	for {
-		n, err := a.JoinWAN(cfg.RetryJoinWan)
-		if err == nil {
-			a.logger.Printf("[INFO] agent: Join -wan completed. Synced with %d initial agents", n)
-			return
-		}
-
-		attempt++
-		if cfg.RetryMaxAttemptsWan > 0 && attempt > cfg.RetryMaxAttemptsWan {
-			a.retryJoinCh <- fmt.Errorf("agent: max join -wan retry exhausted, exiting")
-			return
-		}
-
-		a.logger.Printf("[WARN] agent: Join -wan failed: %v, retrying in %v", err, cfg.RetryIntervalWan)
-		time.Sleep(cfg.RetryIntervalWan)
+		r.logger.Printf("[WARN] agent: Join %s failed: %v, retrying in %v", r.cluster, err, r.interval)
+		time.Sleep(r.interval)
 	}
 }