feat: frontend middleware to block matching urls

CHANGELOG.md

@@ -49,8 +49,8 @@
 * [ENHANCEMENT] Added new Traces api V2[#3912](https://github.com/grafana/tempo/pull/3912) (@javiermolinar)
 * [ENHANCEMENT] Update to the latest dskit [#3915](https://github.com/grafana/tempo/pull/3915) (@andreasgerstmayr)
 * [ENHANCEMENT] Reduce allocs building queriers sharded requests [#3932](https://github.com/grafana/tempo/pull/3932) (@javiermolinar)
-
 * [ENHANCEMENT] Implement polling tenants concurrently [#3647](https://github.com/grafana/tempo/pull/3647) (@zalegrala)
+* [ENHANCEMENT] Added new middleware to block matching urls [#3963](https://github.com/grafana/tempo/pull/3963) (@javiermolinar)
 * [BUGFIX] Fix panic in certain metrics queries using `rate()` with `by` [#3847](https://github.com/grafana/tempo/pull/3847) (@stoewer)
 * [BUGFIX] Fix double appending the primary iterator on second pass with event iterator [#3903](https://github.com/grafana/tempo/pull/3903) (@ie-pham)
 * [BUGFIX] Fix metrics queries when grouping by attributes that may not exist [#3734](https://github.com/grafana/tempo/pull/3734) (@mdisibio)

docs/sources/tempo/configuration/_index.md

@@ -561,6 +561,9 @@ query_frontend:
     # (default: 0)
     [api_timeout: <duration>]
 
+    # A list of regular expressions for refusing matching requests, these will apply for every request regardless of the endpoint.
+    [url_deny_list: <list of strings> | default = <empty list>]]
+
     search:
 
         # The number of concurrent jobs to execute when searching the backend.

modules/frontend/config.go

@@ -29,6 +29,9 @@ type Config struct {
 	// traceql, tag search, tag value search, trace by id and all streaming gRPC endpoints.
 	// 0 disables
 	APITimeout time.Duration `yaml:"api_timeout,omitempty"`
+
+	// A list of regexes for black listing requests, these will apply for every request regardless the endpoint
+	URLDenyList []string `yaml:"url_deny_list,omitempty"`
 }
 
 type SearchConfig struct {

modules/frontend/frontend.go

@@ -88,12 +88,15 @@ func New(cfg Config, next http.RoundTripper, o overrides.Interface, reader tempo
 	}
 
 	retryWare := pipeline.NewRetryWare(cfg.MaxRetries, registerer)
+
 	cacheWare := pipeline.NewCachingWare(cacheProvider, cache.RoleFrontendSearch, logger)
 	statusCodeWare := pipeline.NewStatusCodeAdjustWare()
 	traceIDStatusCodeWare := pipeline.NewStatusCodeAdjustWareWithAllowedCode(http.StatusNotFound)
+	urlDenyListWare := pipeline.NewURLDenyListWare(cfg.URLDenyList)
 
 	tracePipeline := pipeline.Build(
 		[]pipeline.AsyncMiddleware[combiner.PipelineResponse]{
+			urlDenyListWare,
 			multiTenantMiddleware(cfg, logger),
 			newAsyncTraceIDSharder(&cfg.TraceByID, logger),
 		},
@@ -102,6 +105,7 @@ func New(cfg Config, next http.RoundTripper, o overrides.Interface, reader tempo
 
 	searchPipeline := pipeline.Build(
 		[]pipeline.AsyncMiddleware[combiner.PipelineResponse]{
+			urlDenyListWare,
 			multiTenantMiddleware(cfg, logger),
 			newAsyncSearchSharder(reader, o, cfg.Search.Sharder, logger),
 		},
@@ -110,6 +114,7 @@ func New(cfg Config, next http.RoundTripper, o overrides.Interface, reader tempo
 
 	searchTagsPipeline := pipeline.Build(
 		[]pipeline.AsyncMiddleware[combiner.PipelineResponse]{
+			urlDenyListWare,
 			multiTenantMiddleware(cfg, logger),
 			newAsyncTagSharder(reader, o, cfg.Search.Sharder, parseTagsRequest, logger),
 		},
@@ -118,6 +123,7 @@ func New(cfg Config, next http.RoundTripper, o overrides.Interface, reader tempo
 
 	searchTagValuesPipeline := pipeline.Build(
 		[]pipeline.AsyncMiddleware[combiner.PipelineResponse]{
+			urlDenyListWare,
 			multiTenantMiddleware(cfg, logger),
 			newAsyncTagSharder(reader, o, cfg.Search.Sharder, parseTagValuesRequest, logger),
 		},
@@ -127,6 +133,7 @@ func New(cfg Config, next http.RoundTripper, o overrides.Interface, reader tempo
 	// metrics summary
 	metricsPipeline := pipeline.Build(
 		[]pipeline.AsyncMiddleware[combiner.PipelineResponse]{
+			urlDenyListWare,
 			multiTenantUnsupportedMiddleware(cfg, logger),
 		},
 		[]pipeline.Middleware{statusCodeWare, retryWare},
@@ -135,6 +142,7 @@ func New(cfg Config, next http.RoundTripper, o overrides.Interface, reader tempo
 	// traceql metrics
 	queryRangePipeline := pipeline.Build(
 		[]pipeline.AsyncMiddleware[combiner.PipelineResponse]{
+			urlDenyListWare,
 			multiTenantMiddleware(cfg, logger),
 			newAsyncQueryRangeSharder(reader, o, cfg.Metrics.Sharder, logger),
 		},

modules/frontend/pipeline/deny_list_middleware.go

@@ -0,0 +1,52 @@
+package pipeline
+
+import (
+	"fmt"
+	"regexp"
+
+	"github.com/grafana/tempo/modules/frontend/combiner"
+)
+
+type urlDenylistWare struct {
+	denyList []*regexp.Regexp
+	next     AsyncRoundTripper[combiner.PipelineResponse]
+}
+
+func NewURLDenyListWare(denyList []string) AsyncMiddleware[combiner.PipelineResponse] {
+	compiledDenylist := make([]*regexp.Regexp, 0)
+	for _, v := range denyList {
+		r, err := regexp.Compile(v)
+		if err == nil {
+			compiledDenylist = append(compiledDenylist, r)
+		} else {
+			panic(fmt.Sprintf("error compiling query frontend deny list regex: %s", err))
+		}
+	}
+
+	return AsyncMiddlewareFunc[combiner.PipelineResponse](func(next AsyncRoundTripper[combiner.PipelineResponse]) AsyncRoundTripper[combiner.PipelineResponse] {
+		return &urlDenylistWare{
+			next:     next,
+			denyList: compiledDenylist,
+		}
+	})
+}
+
+func (c urlDenylistWare) RoundTrip(req Request) (Responses[combiner.PipelineResponse], error) {
+	if len(c.denyList) != 0 {
+		err := c.validateRequest(req.HTTPRequest().URL.Path)
+		if err != nil {
+			return NewBadRequest(err), nil
+		}
+	}
+
+	return c.next.RoundTrip(req)
+}
+
+func (c urlDenylistWare) validateRequest(url string) error {
+	for _, v := range c.denyList {
+		if v.MatchString(url) {
+			return fmt.Errorf("Invalid request %s, URL is blacklisted", url)
+		}
+	}
+	return nil
+}

modules/frontend/pipeline/deny_list_middleware_test.go

@@ -0,0 +1,55 @@
+package pipeline
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"net/http"
+	"testing"
+
+	"github.com/grafana/tempo/modules/frontend/combiner"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+var next = AsyncRoundTripperFunc[combiner.PipelineResponse](func(_ Request) (Responses[combiner.PipelineResponse], error) {
+	return NewHTTPToAsyncResponse(&http.Response{
+		StatusCode: 200,
+		Body:       io.NopCloser(bytes.NewReader([]byte{})),
+	}), nil
+})
+
+func TestURLBlackListMiddlewareForEmptyBlackList(t *testing.T) {
+	regexes := []string{}
+	roundTrip := NewURLDenyListWare(regexes).Wrap(next)
+	statusCode := DoRequest(t, "http://localhost:8080/api/v2/traces/123345", roundTrip)
+	assert.Equal(t, 200, statusCode)
+}
+
+func TestURLBlackListMiddlewarePanicsOnSyntacticallyIncorrectRegex(t *testing.T) {
+	regexes := []string{"qr/^(.*\\.traces\\/[a-f0-9]{32}$/"}
+	assert.Panics(t, func() {
+		NewURLDenyListWare(regexes).Wrap(next)
+	})
+}
+
+func TestURLBlackListMiddleware(t *testing.T) {
+	regexes := []string{
+		"^.*v2.*",
+	}
+	roundTrip := NewURLDenyListWare(regexes).Wrap(next)
+	statusCode := DoRequest(t, "http://localhost:9000", roundTrip)
+	assert.Equal(t, 200, statusCode)
+
+	// Blacklisted url
+	statusCode = DoRequest(t, "http://localhost:8080/api/v2/traces/123345", roundTrip)
+	assert.Equal(t, 400, statusCode)
+}
+
+func DoRequest(t *testing.T, url string, rt AsyncRoundTripper[combiner.PipelineResponse]) int {
+	req, _ := http.NewRequest(http.MethodGet, url, nil)
+	resp, _ := rt.RoundTrip(NewHTTPRequest(req))
+	httpResponse, _, err := resp.Next(context.Background())
+	require.NoError(t, err)
+	return httpResponse.HTTPResponse().StatusCode
+}