Add custom check endpoint

Replace previously hardcoded value for `/health` to check when the
server became ready to serve traffic. With this the server can support
any server that provides an an OpenAI compatible inference endpoint.

README.md

@@ -30,6 +30,13 @@ models:
     - "gpt-4o-mini"
     - "gpt-3.5-turbo"
 
+    # wait for this path to return an HTTP 200 before serving requests
+    # defaults to /health to match llama.cpp
+    #
+    # use "none" to skip endpoint checking. This may cause requests to fail
+    # until the server is ready
+    checkEndpoint: "/custom-endpoint"
+
   "qwen":
     # environment variables to pass to the command
     env:

config.example.yaml

@@ -10,6 +10,10 @@ models:
     # list of model name aliases this llama.cpp instance can serve
     aliases:
     - "gpt-4o-mini"
+
+    # check this path for a HTTP 200 response for the server to be ready
+    checkEndpoint: "/health"
+
   "qwen":
     cmd: "models/llama-server-osx --port 8999 -m models/Qwen2.5-1.5B-Instruct-Q4_K_M.gguf"
     proxy: "http://127.0.0.1:8999"
@@ -24,6 +28,10 @@ models:
     cmd: "build/simple-responder --port 8999"
     proxy: "http://127.0.0.1:8999"
 
+    # use "none" to skip check. Caution this may cause some requests to fail
+    # until the upstream server is ready for traffic
+    checkEndpoint: "none"
+
   # don't use this, just for testing if things are broken
   "broken":
     cmd: "models/llama-server-osx --port 8999 -m models/doesnotexist.gguf"

llama-swap.go

@@ -25,7 +25,7 @@ func main() {
 	proxyManager := proxy.New(config)
 	http.HandleFunc("/", proxyManager.HandleFunc)
 
-	fmt.Println("llamagate listening on " + *listenStr)
+	fmt.Println("llama-swap listening on " + *listenStr)
 	if err := http.ListenAndServe(*listenStr, nil); err != nil {
 		fmt.Printf("Error starting server: %v\n", err)
 		os.Exit(1)

proxy/config.go

@@ -11,6 +11,7 @@ type ModelConfig struct {
 	Proxy         string   `yaml:"proxy"`
 	Aliases       []string `yaml:"aliases"`
 	Env           []string `yaml:"env"`
+	CheckEndpoint string   `yaml:"checkEndpoint"`
 }
 
 type Config struct {

proxy/manager.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"net/url"
 	"os"
 	"os/exec"
 	"strings"
@@ -89,11 +90,23 @@ func (pm *ProxyManager) checkHealthEndpoint() error {
 		return fmt.Errorf("no upstream available to check /health")
 	}
 
+	checkEndpoint := strings.TrimSpace(pm.currentConfig.CheckEndpoint)
+
+	if checkEndpoint == "none" {
+		return nil
+	}
+
+	// keep default behaviour
+	if checkEndpoint == "" {
+		checkEndpoint = "/health"
+	}
+
 	proxyTo := pm.currentConfig.Proxy
-
 	maxDuration := time.Second * time.Duration(pm.config.HealthCheckTimeout)
-
+	healthURL, err := url.JoinPath(proxyTo, checkEndpoint)
-	healthURL := proxyTo + "/health"
+	if err != nil {
+		return fmt.Errorf("failed to create health url with with %s and path %s", proxyTo, checkEndpoint)
+	}
 	client := &http.Client{}
 	startTime := time.Now()
 
@@ -112,12 +125,12 @@ func (pm *ProxyManager) checkHealthEndpoint() error {
 				// if TCP dial can't connect any HTTP response after 5 seconds
 				// exit quickly.
 				if time.Since(startTime) > 5*time.Second {
-					return fmt.Errorf("/healthy endpoint took more than 5 seconds to respond")
+					return fmt.Errorf("health check endpoint took more than 5 seconds to respond")
 				}
 			}
 
 			if time.Since(startTime) >= maxDuration {
-				return fmt.Errorf("failed to check /healthy from: %s", healthURL)
+				return fmt.Errorf("failed to check health from: %s", healthURL)
 			}
 			time.Sleep(time.Second)
 			continue
@@ -127,7 +140,7 @@ func (pm *ProxyManager) checkHealthEndpoint() error {
 			return nil
 		}
 		if time.Since(startTime) >= maxDuration {
-			return fmt.Errorf("failed to check /healthy from: %s", healthURL)
+			return fmt.Errorf("failed to check health from: %s", healthURL)
 		}
 		time.Sleep(time.Second)
 	}