From 4666d85a29555695511ec3c657bb497bcd3219ae Mon Sep 17 00:00:00 2001
From: Michael Schurter <schmichael@hashicorp.com>
Date: Mon, 24 Jul 2017 16:48:40 -0700
Subject: [PATCH] Use seen more conservatively

---
 command/agent/agent.go         |  8 --------
 command/agent/consul/client.go | 25 +++++++++++--------------
 2 files changed, 11 insertions(+), 22 deletions(-)

diff --git a/command/agent/agent.go b/command/agent/agent.go
index 0f937fb86..251121cdb 100644
--- a/command/agent/agent.go
+++ b/command/agent/agent.go
@@ -704,10 +704,8 @@ func (a *Agent) setupConsul(consulConfig *config.ConsulConfig) error {
 	}
 
 	// Determine version for TLSSkipVerify
-	seen := false
 	if self, err := client.Agent().Self(); err == nil {
 		a.consulSupportsTLSSkipVerify = consulSupportsTLSSkipVerify(self)
-		seen = true
 	}
 
 	// Create Consul Catalog client for service discovery.
@@ -716,12 +714,6 @@ func (a *Agent) setupConsul(consulConfig *config.ConsulConfig) error {
 	// Create Consul Service client for service advertisement and checks.
 	a.consulService = consul.NewServiceClient(client.Agent(), a.consulSupportsTLSSkipVerify, a.logger)
 
-	// If we've seen the Consul agent already, mark it so future Consul
-	// errors are logged
-	if seen {
-		a.consulService.MarkSeen()
-	}
-
 	// Run the Consul service client's sync'ing main loop
 	go a.consulService.Run()
 	return nil
diff --git a/command/agent/consul/client.go b/command/agent/consul/client.go
index 1bd89944e..e3e9a9eea 100644
--- a/command/agent/consul/client.go
+++ b/command/agent/consul/client.go
@@ -147,15 +147,15 @@ func NewServiceClient(consulClient AgentAPI, skipVerifySupport bool, logger *log
 // seen is used by MarkSeen and Seen
 const seen = 1
 
-// MarkSeen marks Consul as having been seen (meaning at least one operation
+// markSeen marks Consul as having been seen (meaning at least one operation
 // has succeeded).
-func (c *ServiceClient) MarkSeen() {
+func (c *ServiceClient) markSeen() {
 	atomic.StoreInt64(&c.seen, seen)
 }
 
-// Seen returns true if any Consul operation has ever succeeded. Useful to
+// hasSeen returns true if any Consul operation has ever succeeded. Useful to
 // squelch errors if Consul isn't running.
-func (c *ServiceClient) Seen() bool {
+func (c *ServiceClient) hasSeen() bool {
 	return atomic.LoadInt64(&c.seen) == seen
 }
 
@@ -175,11 +175,8 @@ func (c *ServiceClient) Run() {
 		}
 
 		if err := c.sync(); err != nil {
-			// Only log and track failures after Consul has been seen
-			if c.Seen() {
-				if failures == 0 {
-					c.logger.Printf("[WARN] consul.sync: failed to update services in Consul: %v", err)
-				}
+			if failures == 0 {
+				c.logger.Printf("[WARN] consul.sync: failed to update services in Consul: %v", err)
 			}
 			failures++
 			if !retryTimer.Stop() {
@@ -264,9 +261,6 @@ func (c *ServiceClient) sync() error {
 		return fmt.Errorf("error querying Consul services: %v", err)
 	}
 
-	// A Consul operation has succeeded, mark Consul as having been seen
-	c.MarkSeen()
-
 	consulChecks, err := c.client.Checks()
 	if err != nil {
 		metrics.IncrCounter([]string{"client", "consul", "sync_failure"}, 1)
@@ -362,6 +356,9 @@ func (c *ServiceClient) sync() error {
 		}
 	}
 
+	// A Consul operation has succeeded, mark Consul as having been seen
+	c.markSeen()
+
 	c.logger.Printf("[DEBUG] consul.sync: registered %d services, %d checks; deregistered %d services, %d checks",
 		sreg, creg, sdereg, cdereg)
 	return nil
@@ -692,8 +689,8 @@ func (c *ServiceClient) Shutdown() error {
 		// Don't wait forever though
 	}
 
-	// If Consul was never seen, exit early
-	if !c.Seen() {
+	// If Consul was never seen nothing could be written so exit early
+	if !c.hasSeen() {
 		return nil
 	}