Fix parsing of vector expression (grafana#8448)

Signed-off-by: Christian Haudum <[email protected]>

Author: chaudum

CHANGELOG.md

@@ -41,6 +41,7 @@
 * [8120](https://github.com/grafana/loki/pull/8120) **ashwanthgoli** fix panic on hitting /scheduler/ring when ring is disabled.
 * [8251](https://github.com/grafana/loki/pull/8251) **sandeepsukhani** index-store: fix indexing of chunks overlapping multiple schemas.
 * [8151](https://github.com/grafana/loki/pull/8151) **sandeepsukhani** fix log deletion with line filters.
+* [8448](https://github.com/grafana/loki/pull/8448) **chaudum**: Fix bug in LogQL parser that caused certain queries that contain a vector expression to fail.
 
 ##### Changes
 

pkg/logql/syntax/ast.go

@@ -1755,7 +1755,7 @@ func (e *VectorExpr) Value() (float64, error) {
 
 func (e *VectorExpr) Selector() (LogSelectorExpr, error)      { return e, e.err }
 func (e *VectorExpr) HasFilter() bool                         { return false }
-func (e *VectorExpr) Shardable() bool                         { return true }
+func (e *VectorExpr) Shardable() bool                         { return false }
 func (e *VectorExpr) Walk(f WalkFn)                           { f(e) }
 func (e *VectorExpr) Pipeline() (log.Pipeline, error)         { return log.NewNoopPipeline(), nil }
 func (e *VectorExpr) Matchers() []*labels.Matcher             { return nil }

pkg/logql/syntax/parser.go

@@ -103,19 +103,12 @@ func ParseExprWithoutValidation(input string) (expr Expr, err error) {
 func validateExpr(expr Expr) error {
 	switch e := expr.(type) {
 	case SampleExpr:
-		err := validateSampleExpr(e)
-		if err != nil {
-			return err
-		}
+		return validateSampleExpr(e)
 	case LogSelectorExpr:
-		err := validateMatchers(e.Matchers())
-		if err != nil {
-			return err
-		}
+		return validateLogSelectorExpression(e)
 	default:
 		return logqlmodel.NewParseError(fmt.Sprintf("unexpected expression type: %v", e), 0, 0)
 	}
-	return nil
 }
 
 // validateMatchers checks whether a query would touch all the streams in the query range or uses at least one matcher to select specific streams.
@@ -169,7 +162,6 @@ func validateSampleExpr(expr SampleExpr) error {
 			return err
 		}
 		return validateSampleExpr(e.RHS)
-
 	case *LiteralExpr:
 		if e.err != nil {
 			return e.err
@@ -195,7 +187,16 @@ func validateSampleExpr(expr SampleExpr) error {
 		if err != nil {
 			return err
 		}
-		return validateMatchers(selector.Matchers())
+		return validateLogSelectorExpression(selector)
+	}
+}
+
+func validateLogSelectorExpression(expr LogSelectorExpr) error {
+	switch e := expr.(type) {
+	case *VectorExpr:
+		return nil
+	default:
+		return validateMatchers(e.Matchers())
 	}
 }
 

pkg/logql/syntax/parser_test.go

@@ -2867,6 +2867,23 @@ func TestParse(t *testing.T) {
 			in:  `vector(abc)`,
 			err: logqlmodel.NewParseError("syntax error: unexpected IDENTIFIER, expecting NUMBER", 1, 8),
 		},
+		{
+			in:  `vector(1)`,
+			exp: &VectorExpr{Val: 1, err: nil},
+		},
+		{
+			in:  `label_replace(vector(0), "foo", "bar", "", "")`,
+			exp: mustNewLabelReplaceExpr(&VectorExpr{Val: 0, err: nil}, "foo", "bar", "", ""),
+		},
+		{
+			in: `sum(vector(0))`,
+			exp: &VectorAggregationExpr{
+				Left:      &VectorExpr{Val: 0, err: nil},
+				Grouping:  &Grouping{},
+				Params:    0,
+				Operation: "sum",
+			},
+		},
 		{
 			in: `{app="foo"}
 					# |= "bar"

pkg/querier/queryrange/querysharding.go

@@ -129,9 +129,6 @@ func (ast *astMapperware) Do(ctx context.Context, r queryrangebase.Request) (que
 	}
 
 	mapper := logql.NewShardMapper(resolver, ast.metrics)
-	if err != nil {
-		return nil, err
-	}
 
 	noop, parsed, err := mapper.Parse(r.GetQuery())
 	if err != nil {