add support for automatically unloading a model (#10) (#14)

* Make starting upstream process on-demand (#10)
* Add automatic unload of model after TTL is reached
* add `ttl` configuration parameter to models in seconds, default is 0 (never unload)

Makefile

@@ -10,6 +10,9 @@ clean:
 	rm -rf $(BUILD_DIR)
 
 test:
+	go test -short -v ./proxy
+
+test-all:
 	go test -v ./proxy
 
 # Build OSX binary

README.md

@@ -39,6 +39,11 @@ models:
     # until the server is ready
     checkEndpoint: /custom-endpoint
 
+    # automatically unload the model after 10 seconds
+    # ttl values must be a value greater than 0
+    # default: 0 = never unload model
+    ttl: 5
+
   "qwen":
     # environment variables to pass to the command
     env:

config.example.yaml

@@ -17,6 +17,9 @@ models:
     # check this path for a HTTP 200 response for the server to be ready
     checkEndpoint: /health
 
+    # unload model after 5 seconds
+    ttl: 5
+
   "qwen":
     cmd: models/llama-server-osx --port 8999 -m models/qwen2.5-0.5b-instruct-q8_0.gguf
     proxy: http://127.0.0.1:8999

misc/simple-responder/simple-responder.go

@@ -20,7 +20,11 @@ func main() {
 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		// Set the header to text/plain
 		w.Header().Set("Content-Type", "text/plain")
+		fmt.Fprintln(w, *responseMessage)
+	})
 
+	http.HandleFunc("/env", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "text/plain")
 		fmt.Fprintln(w, *responseMessage)
 
 		// Get environment variables

proxy/config.go

@@ -14,6 +14,7 @@ type ModelConfig struct {
 	Aliases       []string `yaml:"aliases"`
 	Env           []string `yaml:"env"`
 	CheckEndpoint string   `yaml:"checkEndpoint"`
+	UnloadAfter   int      `yaml:"ttl"`
 }
 
 func (m *ModelConfig) SanitizedCommand() ([]string, error) {

proxy/process.go

@@ -17,27 +17,33 @@ import (
 type Process struct {
 	sync.Mutex
 
-	ID         string
+	ID                 string
-	config     ModelConfig
+	config             ModelConfig
-	cmd        *exec.Cmd
+	cmd                *exec.Cmd
-	logMonitor *LogMonitor
+	logMonitor         *LogMonitor
+	healthCheckTimeout int
+
+	isRunning          bool
+	lastRequestHandled time.Time
 }
 
-func NewProcess(ID string, config ModelConfig, logMonitor *LogMonitor) *Process {
+func NewProcess(ID string, healthCheckTimeout int, config ModelConfig, logMonitor *LogMonitor) *Process {
 	return &Process{
-		ID:         ID,
+		ID:                 ID,
-		config:     config,
+		config:             config,
-		cmd:        nil,
+		cmd:                nil,
-		logMonitor: logMonitor,
+		logMonitor:         logMonitor,
+		healthCheckTimeout: healthCheckTimeout,
 	}
 }
 
-func (p *Process) Start(healthCheckTimeout int) error {
+// start the process and check it for errors
+func (p *Process) start() error {
 	p.Lock()
 	defer p.Unlock()
 
-	if p.cmd != nil {
+	if p.isRunning {
-		return fmt.Errorf("process already started")
+		return fmt.Errorf("process already running")
 	}
 
 	args, err := p.config.SanitizedCommand()
@@ -51,6 +57,8 @@ func (p *Process) Start(healthCheckTimeout int) error {
 	p.cmd.Env = p.config.Env
 
 	err = p.cmd.Start()
+	p.isRunning = true
+
 	if err != nil {
 		return err
 	}
@@ -58,7 +66,8 @@ func (p *Process) Start(healthCheckTimeout int) error {
 	// watch for the command to exit
 	cmdCtx, cancel := context.WithCancelCause(context.Background())
 
-	// monitor the command's exit status
+	// monitor the command's exit status. Usually this happens if
+	// the process exited unexpectedly
 	go func() {
 		err := p.cmd.Wait()
 		if err != nil {
@@ -66,13 +75,37 @@ func (p *Process) Start(healthCheckTimeout int) error {
 		} else {
 			cancel(nil)
 		}
+
+		p.isRunning = false
 	}()
 
+	// wait a bit for process to start before checking the health endpoint
+	time.Sleep(250 * time.Millisecond)
+
 	// wait for checkHealthEndpoint
-	if err := p.checkHealthEndpoint(cmdCtx, healthCheckTimeout); err != nil {
+	if err := p.checkHealthEndpoint(cmdCtx); err != nil {
 		return err
 	}
 
+	if p.config.UnloadAfter > 0 {
+		// start a goroutine to check every second if
+		// the process should be stopped
+		go func() {
+			ticker := time.NewTicker(time.Second)
+			defer ticker.Stop()
+			maxDuration := time.Duration(p.config.UnloadAfter) * time.Second
+
+			for {
+				<-ticker.C
+				if time.Since(p.lastRequestHandled) > maxDuration {
+					fmt.Fprintf(p.logMonitor, "!!! Unloading model %s, TTL of %d reached.\n", p.ID, p.config.UnloadAfter)
+					p.Stop()
+					return
+				}
+			}
+		}()
+	}
+
 	return nil
 }
 
@@ -80,15 +113,20 @@ func (p *Process) Stop() {
 	p.Lock()
 	defer p.Unlock()
 
-	if p.cmd == nil {
+	if !p.isRunning {
 		return
 	}
 
 	p.cmd.Process.Signal(syscall.SIGTERM)
 	p.cmd.Process.Wait()
+	p.isRunning = false
 }
 
-func (p *Process) checkHealthEndpoint(cmdCtx context.Context, healthCheckTimeout int) error {
+func (p *Process) IsRunning() bool {
+	return p.isRunning
+}
+
+func (p *Process) checkHealthEndpoint(cmdCtx context.Context) error {
 	if p.config.Proxy == "" {
 		return fmt.Errorf("no upstream available to check /health")
 	}
@@ -105,7 +143,7 @@ func (p *Process) checkHealthEndpoint(cmdCtx context.Context, healthCheckTimeout
 	}
 
 	proxyTo := p.config.Proxy
-	maxDuration := time.Second * time.Duration(healthCheckTimeout)
+	maxDuration := time.Second * time.Duration(p.healthCheckTimeout)
 	healthURL, err := url.JoinPath(proxyTo, checkEndpoint)
 	if err != nil {
 		return fmt.Errorf("failed to create health url with with %s and path %s", proxyTo, checkEndpoint)
@@ -115,7 +153,6 @@ func (p *Process) checkHealthEndpoint(cmdCtx context.Context, healthCheckTimeout
 	startTime := time.Now()
 
 	for {
-		time.Sleep(time.Second)
 		req, err := http.NewRequest("GET", healthURL, nil)
 		if err != nil {
 			return err
@@ -162,15 +199,22 @@ func (p *Process) checkHealthEndpoint(cmdCtx context.Context, healthCheckTimeout
 		if ttl < 0 {
 			return fmt.Errorf("failed to check health from: %s", healthURL)
 		}
+
+		time.Sleep(time.Second)
 	}
 }
 
 func (p *Process) ProxyRequest(w http.ResponseWriter, r *http.Request) {
-	if p.cmd == nil {
+	if !p.isRunning {
-		http.Error(w, "process not started", http.StatusInternalServerError)
+		if err := p.start(); err != nil {
-		return
+			errstr := fmt.Sprintf("unable to start process: %s", err)
+			http.Error(w, errstr, http.StatusInternalServerError)
+			return
+		}
 	}
 
+	p.lastRequestHandled = time.Now()
+
 	proxyTo := p.config.Proxy
 	client := &http.Client{}
 	req, err := http.NewRequest(r.Method, proxyTo+r.URL.String(), r.Body)

proxy/process_test.go

@@ -2,14 +2,17 @@ package proxy
 
 import (
 	"fmt"
+	"io"
 	"math/rand"
 	"net/http"
 	"net/http/httptest"
 	"os"
 	"path/filepath"
 	"runtime"
-	"strings"
 	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
 )
 
 // Check if the binary exists
@@ -29,53 +32,40 @@ func getBinaryPath() string {
 	return filepath.Join("..", "build", fmt.Sprintf("simple-responder_%s_%s", goos, goarch))
 }
 
-func TestProcess_ProcessStartStop(t *testing.T) {
+func getTestSimpleResponderConfig(expectedMessage string) ModelConfig {
 	// Define the range
 	min := 12000
 	max := 13000
 
 	// Generate a random number between 12000 and 13000
 	randomPort := rand.Intn(max-min+1) + min
-
 	binaryPath := getBinaryPath()
 
-	// Create a log monitor
-	logMonitor := NewLogMonitor()
-
-	expectedMessage := "testing91931"
-
 	// Create a process configuration
-	config := ModelConfig{
+	return ModelConfig{
 		Cmd:           fmt.Sprintf("%s --port %d --respond '%s'", binaryPath, randomPort, expectedMessage),
 		Proxy:         fmt.Sprintf("http://127.0.0.1:%d", randomPort),
 		CheckEndpoint: "/health",
 	}
+}
+
+func TestProcess_AutomaticallyStartsUpstream(t *testing.T) {
+	logMonitor := NewLogMonitorWriter(io.Discard)
+	expectedMessage := "testing91931"
+	config := getTestSimpleResponderConfig(expectedMessage)
 
 	// Create a process
-	process := NewProcess("test-process", config, logMonitor)
+	process := NewProcess("test-process", 5, config, logMonitor)
-
-	// Start the process
-	t.Logf("Starting %s on port %d", binaryPath, randomPort)
-	err := process.Start(5)
-	if err != nil {
-		t.Fatalf("Failed to start process: %v", err)
-	}
-
-	// Create a test request
 	req := httptest.NewRequest("GET", "/", nil)
 	w := httptest.NewRecorder()
 
-	// Proxy the request
+	// process is automatically started
+	assert.False(t, process.IsRunning())
 	process.ProxyRequest(w, req)
+	assert.True(t, process.IsRunning())
 
-	// Check the response
+	assert.Equal(t, http.StatusOK, w.Code, "Expected status code %d, got %d", http.StatusOK, w.Code)
-	if w.Code != http.StatusOK {
+	assert.Contains(t, w.Body.String(), expectedMessage)
-		t.Errorf("Expected status code %d, got %d", http.StatusOK, w.Code)
-	}
-
-	if !strings.Contains(w.Body.String(), expectedMessage) {
-		t.Errorf("Expected body to contain '%s', got %q", expectedMessage, w.Body.String())
-	}
 
 	// Stop the process
 	process.Stop()
@@ -86,8 +76,53 @@ func TestProcess_ProcessStartStop(t *testing.T) {
 	// Proxy the request
 	process.ProxyRequest(w, req)
 
-	// Check the response
+	// should have automatically started the process again
-	if w.Code == http.StatusInternalServerError {
+	if w.Code != http.StatusOK {
-		t.Errorf("Expected status code %d, got %d", http.StatusInternalServerError, w.Code)
+		t.Errorf("Expected status code %d, got %d", http.StatusOK, w.Code)
 	}
 }
+
+// test that the automatic start returns the expected error type
+func TestProcess_BrokenModelConfig(t *testing.T) {
+	// Create a process configuration
+	config := ModelConfig{
+		Cmd:           "nonexistant-command",
+		Proxy:         "http://127.0.0.1:9913",
+		CheckEndpoint: "/health",
+	}
+
+	process := NewProcess("broken", 1, config, NewLogMonitor())
+	req := httptest.NewRequest("GET", "/", nil)
+	w := httptest.NewRecorder()
+	process.ProxyRequest(w, req)
+	assert.Equal(t, http.StatusInternalServerError, w.Code)
+	assert.Contains(t, w.Body.String(), "unable to start process")
+}
+
+func TestProcess_UnloadAfterTTL(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping long auto unload TTL test")
+	}
+
+	expectedMessage := "I_sense_imminent_danger"
+	config := getTestSimpleResponderConfig(expectedMessage)
+	assert.Equal(t, 0, config.UnloadAfter)
+	config.UnloadAfter = 3 // seconds
+	assert.Equal(t, 3, config.UnloadAfter)
+
+	process := NewProcess("ttl", 2, config, NewLogMonitorWriter(io.Discard))
+	req := httptest.NewRequest("GET", "/", nil)
+	w := httptest.NewRecorder()
+
+	// Proxy the request (auto start)
+	process.ProxyRequest(w, req)
+	assert.Equal(t, http.StatusOK, w.Code, "Expected status code %d, got %d", http.StatusOK, w.Code)
+	assert.Contains(t, w.Body.String(), expectedMessage)
+
+	assert.True(t, process.IsRunning())
+
+	// wait 5 seconds
+	time.Sleep(5 * time.Second)
+
+	assert.False(t, process.IsRunning())
+}

proxy/proxymanager.go

@@ -99,8 +99,8 @@ func (pm *ProxyManager) swapModel(requestedModel string) error {
 		}
 	}
 
-	pm.currentProcess = NewProcess(modelID, modelConfig, pm.logMonitor)
+	pm.currentProcess = NewProcess(modelID, pm.config.HealthCheckTimeout, modelConfig, pm.logMonitor)
-	return pm.currentProcess.Start(pm.config.HealthCheckTimeout)
+	return nil
 }
 
 func (pm *ProxyManager) proxyChatRequestHandler(c *gin.Context) {