very rudimentary impl

.gitignore

@@ -1,22 +1,22 @@
-# ---> Rust
+# Binaries for programs and plugins
-# Generated by Cargo
+*.exe
-# will have compiled files and executables
+*.exe~
-debug/
+*.dll
-target/
+*.so
+*.dylib
 
-# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# Test binary, built with `go test -c`
-# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
+*.test
-Cargo.lock
 
-# These are backup files generated by rustfmt
+# Output of the go coverage tool, specifically when used with LiteIDE
-**/*.rs.bk
+*.out
 
-# MSVC Windows builds of rustc generate these, which store debugging information
+# Dependency directories (remove the comment below to include it)
-*.pdb
+# vendor/
 
-# RustRover
+# Go workspace file
-#  JetBrains specific template is maintained in a separate JetBrains.gitignore that can
+go.work
-#  be found at https://github.com/github/gitignore/blob/main/Global/JetBrains.gitignore
+go.work.sum
-#  and can be added to the global gitignore or merged into this file.  For a more nuclear
+
-#  option (not recommended) you can uncomment the following to ignore the entire idea folder.
+# env file
-#.idea/
+.env

go.mod

@@ -0,0 +1,8 @@
+module ade9/llmproxymetrics
+
+go 1.23.3
+
+require (
+	github.com/caarlos0/env v3.5.0+incompatible
+	github.com/caarlos0/env/v11 v11.3.1 // indirect
+)

go.sum

@@ -0,0 +1,4 @@
+github.com/caarlos0/env v3.5.0+incompatible h1:Yy0UN8o9Wtr/jGHZDpCBLpNrzcFLLM2yixi/rBrKyJs=
+github.com/caarlos0/env v3.5.0+incompatible/go.mod h1:tdCsowwCzMLdkqRYDlHpZCp2UooDD3MspDBjZ2AD02Y=
+github.com/caarlos0/env/v11 v11.3.1 h1:cArPWC15hWmEt+gWk7YBi7lEXTXCvpaSdCiZE2X5mCA=
+github.com/caarlos0/env/v11 v11.3.1/go.mod h1:qupehSf/Y0TUTsxKywqRt/vJjN5nz6vauiYEUUr8P4U=

llmproxymetrics.go

@@ -0,0 +1,105 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"log"
+	"net/http"
+	"net/http/httptest"
+	"net/http/httputil"
+	"net/url"
+	"strconv"
+	"time"
+
+	"github.com/caarlos0/env/v11"
+)
+
+var cfg config
+
+type config struct {
+	BaseURL string `env:"BASE_URL"`
+	Port    int    `env:"PORT"`
+}
+
+func createProxy(target *url.URL) func(http.ResponseWriter, *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		r.Host = target.Host
+		r.URL.Scheme = target.Scheme
+		r.URL.Host = target.Host
+
+		lrw := &LoggingResponseWriter{ResponseWriter: w, body: new(bytes.Buffer)}
+		proxy := httputil.NewSingleHostReverseProxy(target)
+
+		startTime := time.Now()
+		recorder := httptest.NewRecorder()
+		proxy.ServeHTTP(recorder, r)
+
+		responseBody := recorder.Body.Bytes()
+
+		var jsonResponse map[string]interface{}
+		err := json.Unmarshal(responseBody, &jsonResponse)
+		if err != nil {
+			log.Printf("Error unmarshalling JSON response: %v", err)
+			lrw.Write(responseBody)
+			return
+		}
+
+		// Add your metrics metadata here
+		jsonResponse["metrics"] = map[string]interface{}{
+			"requestPath":  r.URL.Path,
+			"statusCode":   recorder.Code,
+			"responseTime": time.Since(startTime).Milliseconds(),
+			// Add more metrics as needed
+		}
+
+		modifiedResponseBody, err := json.Marshal(jsonResponse)
+		if err != nil {
+			log.Printf("Error marshalling modified JSON response: %v", err)
+			lrw.Write(responseBody)
+			return
+		}
+
+		for name, values := range recorder.Header() {
+			for _, value := range values {
+				w.Header().Add(name, value)
+			}
+		}
+
+		w.WriteHeader(recorder.Code)
+		lrw.Write(modifiedResponseBody)
+
+		log.Printf("Response with metrics: %s", lrw.Body())
+	}
+}
+
+type LoggingResponseWriter struct {
+	http.ResponseWriter
+	body *bytes.Buffer
+}
+
+func (lrw *LoggingResponseWriter) Write(b []byte) (int, error) {
+	lrw.body.Write(b)
+	return lrw.ResponseWriter.Write(b)
+}
+
+func (lrw *LoggingResponseWriter) Body() string {
+	return lrw.body.String()
+}
+
+func main() {
+	env.Parse(&cfg)
+
+	targetURL, err := url.Parse(cfg.BaseURL)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	http.HandleFunc("/", createProxy(targetURL))
+
+	log.Printf("Starting proxy server on :%s", strconv.Itoa(cfg.Port))
+	err = http.ListenAndServe(fmt.Sprintf(":%s", strconv.Itoa(cfg.Port)), nil)
+	if err != nil {
+		log.Fatal(err)
+	}
+}