add a basic http request filter

internal/processing/http-request-filter.go

@@ -0,0 +1,78 @@
+package processing
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"regexp"
+)
+
+type HTTPRequestFilter struct {
+	config ProcessorConfig
+	Path   *regexp.Regexp
+	Method string
+}
+
+func (hrf *HTTPRequestFilter) Process(ctx context.Context, payload any) (any, error) {
+
+	payloadRequest, ok := payload.(*http.Request)
+
+	if !ok {
+		return nil, fmt.Errorf("http.request.filter can only operate on http.Request payloads")
+	}
+
+	if hrf.Method != "" {
+		if payloadRequest.Method != hrf.Method {
+			return nil, nil
+		}
+	}
+
+	if !hrf.Path.MatchString(payloadRequest.URL.Path) {
+		return nil, nil
+	}
+
+	return payloadRequest, nil
+}
+
+func (hrf *HTTPRequestFilter) Type() string {
+	return hrf.config.Type
+}
+
+func init() {
+	RegisterProcessor(ProcessorRegistration{
+		Type: "http.request.filter",
+		New: func(config ProcessorConfig) (Processor, error) {
+			params := config.Params
+			path, ok := params["path"]
+
+			if !ok {
+				return nil, fmt.Errorf("http.request.filter requires an path parameter")
+			}
+
+			pathString, ok := path.(string)
+
+			if !ok {
+				return nil, fmt.Errorf("http.request.filter path must be a string")
+			}
+
+			pathRegexp, err := regexp.Compile(fmt.Sprintf("^%s$", pathString))
+
+			if err != nil {
+				return nil, err
+			}
+
+			method, ok := params["method"]
+
+			if ok {
+				methodString, ok := method.(string)
+
+				if !ok {
+					return nil, fmt.Errorf("http.request.filter method must be a string")
+				}
+				return &HTTPRequestFilter{config: config, Path: pathRegexp, Method: methodString}, nil
+			}
+
+			return &HTTPRequestFilter{config: config, Path: pathRegexp}, nil
+		},
+	})
+}