rule: Fix bug when rules were out of sync

CHANGELOG.md

@@ -16,6 +16,7 @@ We use *breaking* word for marking changes that are not backward compatible (rel
 - [#2536](https://github.com/thanos-io/thanos/pull/2536) minio-go: Fixed AWS STS endpoint url to https for Web Identity providers on AWS EKS
 - [#2501](https://github.com/thanos-io/thanos/pull/2501) Query: gracefully handle additional fields in `SeriesResponse` protobuf message that may be added in the future.
 - [#2568](https://github.com/thanos-io/thanos/pull/2568) Query: does not close the connection of strict, static nodes if establishing a connection had succeeded but Info() call failed
+- [#2615](https://github.com/thanos-io/thanos/pull/2615) Rule: Fix bugs where rules were out of sync.
 
 ### Added
 

cmd/thanos/rule.go

@@ -763,8 +763,9 @@ func reloadRules(logger log.Logger,
 	metrics *RuleMetrics) error {
 	level.Debug(logger).Log("msg", "configured rule files", "files", strings.Join(ruleFiles, ","))
 	var (
-		errs  tsdberrors.MultiError
-		files []string
+		errs      tsdberrors.MultiError
+		files     []string
+		seenFiles = make(map[string]struct{})
 	)
 	for _, pat := range ruleFiles {
 		fs, err := filepath.Glob(pat)
@@ -774,7 +775,13 @@ func reloadRules(logger log.Logger,
 			continue
 		}
 
-		files = append(files, fs...)
+		for _, fp := range fs {
+			if _, ok := seenFiles[fp]; ok {
+				continue
+			}
+			files = append(files, fp)
+			seenFiles[fp] = struct{}{}
+		}
 	}
 
 	level.Info(logger).Log("msg", "reload rule files", "numFiles", len(files))

pkg/rule/rule.go

@@ -70,17 +70,17 @@ func (m *Manager) SetRuleManager(s storepb.PartialResponseStrategy, mgr *rules.M
 func (m *Manager) RuleGroups() []Group {
 	m.mtx.RLock()
 	defer m.mtx.RUnlock()
-	var res []Group
+	var groups []Group
 	for s, r := range m.mgrs {
 		for _, group := range r.RuleGroups() {
-			res = append(res, Group{
+			groups = append(groups, Group{
 				Group:                   group,
 				PartialResponseStrategy: s,
 				originalFile:            m.ruleFiles[group.File()],
 			})
 		}
 	}
-	return res
+	return groups
 }
 
 func (m *Manager) AlertingRules() []AlertingRule {
@@ -216,6 +216,21 @@ func (m *Manager) Update(evalInterval time.Duration, files []string) error {
 			continue
 		}
 	}
+
+	// Removes the rules from a manager when a strategy has no more rule.
+	for s, mgr := range m.mgrs {
+		if _, ok := filesByStrategy[s]; ok {
+			continue
+		}
+
+		if len(mgr.RuleGroups()) == 0 {
+			continue
+		}
+
+		if err := mgr.Update(evalInterval, []string{}, nil); err != nil {
+			errs = append(errs, err)
+		}
+	}
 	m.ruleFiles = ruleFiles
 	m.mtx.Unlock()
 

pkg/rule/rule_test.go

@@ -66,14 +66,17 @@ groups:
 		Appendable: nopAppendable{},
 	}
 	thanosRuleMgr := NewManager(dir)
-	ruleMgr := rules.NewManager(&opts)
-	thanosRuleMgr.SetRuleManager(storepb.PartialResponseStrategy_ABORT, ruleMgr)
-	thanosRuleMgr.SetRuleManager(storepb.PartialResponseStrategy_WARN, ruleMgr)
+	ruleMgrAbort := rules.NewManager(&opts)
+	ruleMgrWarn := rules.NewManager(&opts)
+	thanosRuleMgr.SetRuleManager(storepb.PartialResponseStrategy_ABORT, ruleMgrAbort)
+	thanosRuleMgr.SetRuleManager(storepb.PartialResponseStrategy_WARN, ruleMgrWarn)
 
-	testutil.Ok(t, thanosRuleMgr.Update(10*time.Second, []string{filepath.Join(dir, "rule.yaml")}))
+	ruleMgrAbort.Run()
+	ruleMgrWarn.Run()
+	defer ruleMgrAbort.Stop()
+	defer ruleMgrWarn.Stop()
 
-	ruleMgr.Run()
-	defer ruleMgr.Stop()
+	testutil.Ok(t, thanosRuleMgr.Update(10*time.Second, []string{filepath.Join(dir, "rule.yaml")}))
 
 	select {
 	case <-time.After(2 * time.Minute):
@@ -225,6 +228,44 @@ groups:
 	}
 }
 
+func TestUpdateAfterClear(t *testing.T) {
+	dir, err := ioutil.TempDir("", "test_rule_rule_groups")
+	testutil.Ok(t, err)
+	defer func() { testutil.Ok(t, os.RemoveAll(dir)) }()
+
+	testutil.Ok(t, ioutil.WriteFile(filepath.Join(dir, "no_strategy.yaml"), []byte(`
+groups:
+- name: "something1"
+  rules:
+  - alert: "some"
+    expr: "up"
+`), os.ModePerm))
+
+	opts := rules.ManagerOptions{
+		Logger: log.NewLogfmtLogger(os.Stderr),
+	}
+	m := NewManager(dir)
+	ruleMgrAbort := rules.NewManager(&opts)
+	ruleMgrWarn := rules.NewManager(&opts)
+	m.SetRuleManager(storepb.PartialResponseStrategy_ABORT, ruleMgrAbort)
+	m.SetRuleManager(storepb.PartialResponseStrategy_WARN, ruleMgrWarn)
+
+	ruleMgrAbort.Run()
+	ruleMgrWarn.Run()
+	defer ruleMgrAbort.Stop()
+	defer ruleMgrWarn.Stop()
+
+	err = m.Update(1*time.Second, []string{
+		filepath.Join(dir, "no_strategy.yaml"),
+	})
+	testutil.Ok(t, err)
+	testutil.Equals(t, 1, len(m.RuleGroups()))
+
+	err = m.Update(1*time.Second, []string{})
+	testutil.Ok(t, err)
+	testutil.Equals(t, 0, len(m.RuleGroups()))
+}
+
 func TestRuleGroupMarshalYAML(t *testing.T) {
 	const expected = `groups:
 - name: something1