feat: support experimental PromQL features (#297)

Signed-off-by: Simon Pasquier <[email protected]>

Author: simonpasquier

CHANGELOG.md

@@ -1,6 +1,8 @@
 ## Unreleased
 
-* [ENHANCEMENT] Add the `-enable-label-matchers-for-rules-api` flag to filter rules using label matchers. #xxx
+* [ENHANCEMENT] Add the `-enable-promql-duration-expression-parsing` flag to support arithmetic for durations in PromQL expressions. #297
+* [ENHANCEMENT] Add the `-enable-promql-experimental-functions` flag to support experimental functions in PromQL expressions. #297
+* [ENHANCEMENT] Add the `-enable-label-matchers-for-rules-api` flag to filter rules using label matchers. #295
 
 ## 0.11.1 / 2025-05-12
 

main.go

@@ -31,6 +31,7 @@ import (
 	"github.com/oklog/run"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/collectors"
+	"github.com/prometheus/prometheus/promql/parser"
 
 	"github.com/prometheus-community/prom-label-proxy/injectproxy"
 )
@@ -55,20 +56,22 @@ func (i *arrayFlags) Set(value string) error {
 
 func main() {
 	var (
-		insecureListenAddress    string
-		internalListenAddress    string
-		upstream                 string
-		queryParam               string
-		headerName               string
-		label                    string
-		labelValues              arrayFlags
-		enableLabelAPIs          bool
-		unsafePassthroughPaths   string // Comma-delimited string.
-		errorOnReplace           bool
-		regexMatch               bool
-		headerUsesListSyntax     bool
-		rulesWithActiveAlerts    bool
-		labelMatchersForRulesAPI bool
+		insecureListenAddress           string
+		internalListenAddress           string
+		upstream                        string
+		queryParam                      string
+		headerName                      string
+		label                           string
+		labelValues                     arrayFlags
+		enableLabelAPIs                 bool
+		unsafePassthroughPaths          string // Comma-delimited string.
+		errorOnReplace                  bool
+		regexMatch                      bool
+		headerUsesListSyntax            bool
+		rulesWithActiveAlerts           bool
+		labelMatchersForRulesAPI        bool
+		promQLDurationExpressionParsing bool
+		promQLExperimentalFunctions     bool
 	)
 
 	flagset := flag.NewFlagSet(os.Args[0], flag.ExitOnError)
@@ -90,6 +93,8 @@ func main() {
 	flagset.BoolVar(&headerUsesListSyntax, "header-uses-list-syntax", false, "When specified, the header line value will be parsed as a comma-separated list. This allows a single tenant header line to specify multiple tenant names.")
 	flagset.BoolVar(&rulesWithActiveAlerts, "rules-with-active-alerts", false, "When true, the proxy will return alerting rules with active alerts matching the tenant label even when the tenant label isn't present in the rule's labels.")
 	flagset.BoolVar(&labelMatchersForRulesAPI, "enable-label-matchers-for-rules-api", false, "When true, the proxy uses label matchers when querying the /api/v1/rules endpoint. NOTE: Enable with care because filtering by label matcher is not implemented in older versions of Prometheus (>= 2.54.0 required) and Thanos (>= v0.25.0 required). If not implemented by upstream, the response will not be filtered accordingly.")
+	flagset.BoolVar(&promQLDurationExpressionParsing, "enable-promql-duration-expression-parsing", false, "When true, the proxy supports arithmetic for durations in PromQL expressions.")
+	flagset.BoolVar(&promQLExperimentalFunctions, "enable-promql-experimental-functions", false, "When true, the proxy supports experimental functions in PromQL expressions.")
 
 	//nolint: errcheck // Parse() will exit on error.
 	flagset.Parse(os.Args[1:])
@@ -176,8 +181,10 @@ func main() {
 		extractLabeler = injectproxy.HTTPHeaderEnforcer{Name: http.CanonicalHeaderKey(headerName), ParseListSyntax: headerUsesListSyntax}
 	}
 
-	var g run.Group
+	parser.ExperimentalDurationExpr = promQLDurationExpressionParsing
+	parser.EnableExperimentalFunctions = promQLExperimentalFunctions
 
+	var g run.Group
 	{
 		// Run the insecure HTTP server.
 		routes, err := injectproxy.NewRoutes(upstreamURL, label, extractLabeler, opts...)