From 6b4a6962d26fff048027679742ad4f0a7b012e6c Mon Sep 17 00:00:00 2001
From: Fabian Reinartz <fab.reinartz@gmail.com>
Date: Mon, 11 Jan 2016 11:39:22 +0100
Subject: [PATCH] Support old alerting rule syntax

---
 promql/lex.go        | 11 ++++++++
 promql/lex_test.go   | 12 +++++++++
 promql/parse.go      | 64 ++++++++++++++++++++++++++++++++++++--------
 promql/parse_test.go | 39 ++++++++++++++++++++-------
 4 files changed, 106 insertions(+), 20 deletions(-)

diff --git a/promql/lex.go b/promql/lex.go
index 2ebb9cc8a..7817d3421 100644
--- a/promql/lex.go
+++ b/promql/lex.go
@@ -162,6 +162,11 @@ const (
 	itemGroupLeft
 	itemGroupRight
 	itemBool
+	// Old alerting syntax
+	itemWith
+	itemSummary
+	itemRunbook
+	itemDescription
 	keywordsEnd
 )
 
@@ -193,6 +198,12 @@ var key = map[string]itemType{
 	"group_left":    itemGroupLeft,
 	"group_right":   itemGroupRight,
 	"bool":          itemBool,
+
+	// Old alerting syntax.
+	"with":        itemWith,
+	"summary":     itemSummary,
+	"runbook":     itemRunbook,
+	"description": itemDescription,
 }
 
 // These are the default string representations for common items. It does not
diff --git a/promql/lex_test.go b/promql/lex_test.go
index 793621a3d..e3f0b4c4e 100644
--- a/promql/lex_test.go
+++ b/promql/lex_test.go
@@ -243,6 +243,18 @@ var tests = []struct {
 	}, {
 		input:    "annotations",
 		expected: []item{{itemAnnotations, 0, "annotations"}},
+	}, {
+		input:    "description",
+		expected: []item{{itemDescription, 0, "description"}},
+	}, {
+		input:    "summary",
+		expected: []item{{itemSummary, 0, "summary"}},
+	}, {
+		input:    "runbook",
+		expected: []item{{itemRunbook, 0, "runbook"}},
+	}, {
+		input:    "with",
+		expected: []item{{itemWith, 0, "with"}},
 	}, {
 		input:    "offset",
 		expected: []item{{itemOffset, 0, "offset"}},
diff --git a/promql/parse.go b/promql/parse.go
index 7e261a225..55a1b10b2 100644
--- a/promql/parse.go
+++ b/promql/parse.go
@@ -371,9 +371,10 @@ func (p *parser) alertStmt() *AlertStmt {
 	expr := p.expr()
 
 	// Optional for clause.
-	var duration time.Duration
-	var err error
-
+	var (
+		duration time.Duration
+		err      error
+	)
 	if p.peek().typ == itemFor {
 		p.next()
 		dur := p.expect(itemDuration, ctx)
@@ -383,23 +384,64 @@ func (p *parser) alertStmt() *AlertStmt {
 		}
 	}
 
-	lset := model.LabelSet{}
-	if p.peek().typ == itemLabels {
+	// Accepting WITH instead of LABELS is temporary compatibility
+	// with the old alerting syntax.
+	var (
+		hasLabels   bool
+		oldSyntax   bool
+		labels      = model.LabelSet{}
+		annotations = model.LabelSet{}
+	)
+	if t := p.peek().typ; t == itemLabels {
 		p.expect(itemLabels, ctx)
-		lset = p.labelSet()
+		labels = p.labelSet()
+		hasLabels = true
+	} else if t == itemWith {
+		p.expect(itemWith, ctx)
+		labels = p.labelSet()
+		oldSyntax = true
 	}
 
-	annotations := model.LabelSet{}
-	if p.peek().typ == itemAnnotations {
-		p.expect(itemAnnotations, ctx)
-		annotations = p.labelSet()
+	// Only allow old annotation syntax if new label syntax isn't used.
+	if !hasLabels {
+	Loop:
+		for {
+			switch p.next().typ {
+			case itemSummary:
+				annotations["summary"] = model.LabelValue(p.unquoteString(p.expect(itemString, ctx).val))
+
+			case itemDescription:
+				annotations["description"] = model.LabelValue(p.unquoteString(p.expect(itemString, ctx).val))
+
+			case itemRunbook:
+				annotations["runbook"] = model.LabelValue(p.unquoteString(p.expect(itemString, ctx).val))
+
+			default:
+				p.backup()
+				break Loop
+			}
+		}
+		if len(annotations) > 0 {
+			oldSyntax = true
+		}
+	}
+
+	// Only allow new annotation syntax if WITH or old annotation
+	// syntax weren't used.
+	if !oldSyntax {
+		if p.peek().typ == itemAnnotations {
+			p.expect(itemAnnotations, ctx)
+			annotations = p.labelSet()
+		}
+	} else {
+		log.Warnf("Alerting rule with old syntax found. Support for this syntax will be removed with 0.18. Please update to the new syntax.")
 	}
 
 	return &AlertStmt{
 		Name:        name.val,
 		Expr:        expr,
 		Duration:    duration,
-		Labels:      lset,
+		Labels:      labels,
 		Annotations: annotations,
 	}
 }
diff --git a/promql/parse_test.go b/promql/parse_test.go
index 4a544cd5e..52a3381e1 100644
--- a/promql/parse_test.go
+++ b/promql/parse_test.go
@@ -1256,10 +1256,37 @@ var testStatement = []struct {
 			},
 		},
 	}, {
-		input: `ALERT SomeName IF some_metric > 1 
+		input: `ALERT SomeName IF some_metric > 1
+			WITH {}
+			SUMMARY "Global request rate low"
+			DESCRIPTION "The global request rate is low"
+		`,
+		expected: Statements{
+			&AlertStmt{
+				Name: "SomeName",
+				Expr: &BinaryExpr{
+					Op: itemGTR,
+					LHS: &VectorSelector{
+						Name: "some_metric",
+						LabelMatchers: metric.LabelMatchers{
+							{Type: metric.Equal, Name: model.MetricNameLabel, Value: "some_metric"},
+						},
+					},
+					RHS: &NumberLiteral{1},
+				},
+				Labels: model.LabelSet{},
+				Annotations: model.LabelSet{
+					"summary":     "Global request rate low",
+					"description": "The global request rate is low",
+				},
+			},
+		},
+	}, {
+		input: `ALERT SomeName IF some_metric > 1
+			LABELS {}
 			ANNOTATIONS {
-			  summary = "Global request rate low",
-			  description = "The global request rate is low"
+				summary = "Global request rate low",
+				description = "The global request rate is low",
 			}
 		`,
 		expected: Statements{
@@ -1333,12 +1360,6 @@ var testStatement = []struct {
 	}, {
 		input: `foo{a!~"b"} = bar`,
 		fail:  true,
-	}, {
-		input: `ALERT SomeName IF time() LABELS {} 
-			SUMMARY "Global request rate low"
-			DESCRIPTION "The global request rate is low"
-		`,
-		fail: true,
 	},
 	// Fuzzing regression tests.
 	{