Test an index=0 value in cache.Notify

agent/agent.go

@@ -2092,8 +2092,10 @@ func (a *Agent) removeServiceLocked(serviceID string, persist bool) error {
 		return fmt.Errorf("ServiceID missing")
 	}
 
-	// Shut down the config watch in the service manager.
-	a.serviceManager.RemoveService(serviceID)
+	// Shut down the config watch in the service manager if enabled.
+	if a.config.EnableCentralServiceConfig {
+		a.serviceManager.RemoveService(serviceID)
+	}
 
 	checks := a.State.Checks()
 	var checkIDs []types.CheckID

agent/cache/watch_test.go

@@ -2,6 +2,7 @@ package cache
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"sync/atomic"
 	"testing"
@@ -23,11 +24,15 @@ func TestCacheNotify(t *testing.T) {
 	})
 
 	// Setup triggers to control when "updates" should be delivered
-	trigger := make([]chan time.Time, 4)
+	trigger := make([]chan time.Time, 5)
 	for i := range trigger {
 		trigger[i] = make(chan time.Time)
 	}
 
+	// Send an error to fake a situation where the servers aren't reachable
+	// initially.
+	typ.Static(FetchResult{Value: nil, Index: 0}, errors.New("no servers available")).Once()
+
 	// Configure the type
 	typ.Static(FetchResult{Value: 1, Index: 4}, nil).Once().Run(func(args mock.Arguments) {
 		// Assert the right request type - all real Fetch implementations do this so
@@ -35,16 +40,16 @@ func TestCacheNotify(t *testing.T) {
 		// break in real life (hint: it did on the first attempt)
 		_, ok := args.Get(1).(*MockRequest)
 		require.True(t, ok)
-	})
-	typ.Static(FetchResult{Value: 12, Index: 5}, nil).Once().WaitUntil(trigger[0])
+	}).WaitUntil(trigger[0])
 	typ.Static(FetchResult{Value: 12, Index: 5}, nil).Once().WaitUntil(trigger[1])
-	typ.Static(FetchResult{Value: 42, Index: 7}, nil).Once().WaitUntil(trigger[2])
+	typ.Static(FetchResult{Value: 12, Index: 5}, nil).Once().WaitUntil(trigger[2])
+	typ.Static(FetchResult{Value: 42, Index: 7}, nil).Once().WaitUntil(trigger[3])
 	// It's timing dependent whether the blocking loop manages to make another
 	// call before we cancel so don't require it. We need to have a higher index
 	// here because if the index is the same then the cache Get will not return
 	// until the full 10 min timeout expires. This causes the last fetch to return
 	// after cancellation as if it had timed out.
-	typ.Static(FetchResult{Value: 42, Index: 8}, nil).WaitUntil(trigger[3])
+	typ.Static(FetchResult{Value: 42, Index: 8}, nil).WaitUntil(trigger[4])
 
 	require := require.New(t)
 
@@ -56,12 +61,12 @@ func TestCacheNotify(t *testing.T) {
 	err := c.Notify(ctx, "t", TestRequest(t, RequestInfo{Key: "hello"}), "test", ch)
 	require.NoError(err)
 
-	// Should receive the first result pretty soon
+	// Should receive the error with index == 0 first.
 	TestCacheNotifyChResult(t, ch, UpdateEvent{
 		CorrelationID: "test",
-		Result:        1,
-		Meta:          ResultMeta{Hit: false, Index: 4},
-		Err:           nil,
+		Result:        nil,
+		Meta:          ResultMeta{Hit: false, Index: 0},
+		Err:           errors.New("no servers available"),
 	})
 
 	// There should be no more updates delivered yet
@@ -70,6 +75,17 @@ func TestCacheNotify(t *testing.T) {
 	// Trigger blocking query to return a "change"
 	close(trigger[0])
 
+	// Should receive the first real update next.
+	TestCacheNotifyChResult(t, ch, UpdateEvent{
+		CorrelationID: "test",
+		Result:        1,
+		Meta:          ResultMeta{Hit: false, Index: 4},
+		Err:           nil,
+	})
+
+	// Trigger blocking query to return a "change"
+	close(trigger[1])
+
 	// Should receive the next result pretty soon
 	TestCacheNotifyChResult(t, ch, UpdateEvent{
 		CorrelationID: "test",
@@ -99,7 +115,7 @@ func TestCacheNotify(t *testing.T) {
 	// We could wait for a full timeout but we can't directly observe it so
 	// simulate the behavior by triggering a response with the same value and
 	// index as the last one.
-	close(trigger[1])
+	close(trigger[2])
 
 	// We should NOT be notified about that. Note this is timing dependent but
 	// it's only a sanity check, if we somehow _do_ get the change delivered later
@@ -108,7 +124,7 @@ func TestCacheNotify(t *testing.T) {
 	require.Len(ch, 0)
 
 	// Trigger final update
-	close(trigger[2])
+	close(trigger[3])
 
 	TestCacheNotifyChResult(t, ch, UpdateEvent{
 		CorrelationID: "test",
@@ -134,7 +150,7 @@ func TestCacheNotify(t *testing.T) {
 	// have no way to interrupt a blocking query. In practice it's fine to know
 	// that after 10 mins max the blocking query will return and the resources
 	// will be cleaned.
-	close(trigger[3])
+	close(trigger[4])
 
 	// I want to test that canceling the context cleans up goroutines (which it
 	// does from manual verification with debugger etc). I had a check based on a

agent/config/runtime.go

@@ -672,7 +672,7 @@ type RuntimeConfig struct {
 	// EnableCentralServiceConfig controls whether the agent should incorporate
 	// centralized config such as service-defaults into local service registrations.
 	//
-	// hcl: (enable)
+	// hcl: enable_central_service_config = (true|false)
 	EnableCentralServiceConfig bool
 
 	// EnableDebug is used to enable various debugging features.