Fix bug in saving host detail update time (#888)

Saving a new detail update time when the host details were not actually updated
caused detail updates to be missed. This PR fixes the existing test to catch
the bug, and fixes the bug.

server/service/service_osquery.go

@@ -494,11 +494,13 @@ func (svc service) SubmitDistributedQueryResults(ctx context.Context, results ko
 		return osqueryError{message: "failed to update host seen: " + err.Error()}
 	}
 
+	detailUpdated := false
 	labelResults := map[string]bool{}
 	for query, rows := range results {
 		switch {
 		case strings.HasPrefix(query, hostDetailQueryPrefix):
 			err = svc.ingestDetailQuery(&host, query, rows)
+			detailUpdated = true
 		case strings.HasPrefix(query, hostLabelQueryPrefix):
 			err = svc.ingestLabelQuery(host, query, rows, labelResults)
 		case strings.HasPrefix(query, hostDistributedQueryPrefix):
@@ -524,10 +526,15 @@ func (svc service) SubmitDistributedQueryResults(ctx context.Context, results ko
 		}
 	}
 
-	host.DetailUpdateTime = svc.clock.Now()
-	err = svc.ds.SaveHost(&host)
-	if err != nil {
-		return osqueryError{message: "failed to update host details: " + err.Error()}
+	if detailUpdated {
+		host.DetailUpdateTime = svc.clock.Now()
+	}
+
+	if len(labelResults) > 0 || detailUpdated {
+		err = svc.ds.SaveHost(&host)
+		if err != nil {
+			return osqueryError{message: "failed to update host details: " + err.Error()}
+		}
 	}
 
 	return nil

server/service/service_osquery_test.go

@@ -590,9 +590,12 @@ func TestDetailQueries(t *testing.T) {
 	// uptime
 	assert.Equal(t, 1730893*time.Second, host.Uptime)
 
-	ctx = hostctx.NewContext(ctx, *host)
+	mockClock.AddTime(1 * time.Minute)
 
 	// Now no detail queries should be required
+	host, err = ds.AuthenticateHost(nodeKey)
+	require.Nil(t, err)
+	ctx = hostctx.NewContext(ctx, *host)
 	queries, err = svc.GetDistributedQueries(ctx)
 	assert.Nil(t, err)
 	assert.Len(t, queries, 0)
@@ -600,6 +603,12 @@ func TestDetailQueries(t *testing.T) {
 	// Advance clock and queries should exist again
 	mockClock.AddTime(1*time.Hour + 1*time.Minute)
 
+	err = svc.SubmitDistributedQueryResults(ctx, kolide.OsqueryDistributedQueryResults{}, map[string]string{})
+	require.Nil(t, err)
+	host, err = ds.AuthenticateHost(nodeKey)
+	require.Nil(t, err)
+
+	ctx = hostctx.NewContext(ctx, *host)
 	queries, err = svc.GetDistributedQueries(ctx)
 	assert.Nil(t, err)
 	assert.Len(t, queries, len(detailQueries))