Improve shutdown behaviour (#47) (#49)

Introduce `Process.Shutdown()` and `ProxyManager.Shutdown()`. These two function required a lot of internal process state management refactoring. A key benefit is that `Process.start()` is now interruptable. When `Shutdown()` is called it will break the long health check loop. 

State management within Process is also improved. Added `starting`, `stopping` and `shutdown` states. Additionally, introduced a simple finite state machine to manage transitions.

README.md

@@ -5,7 +5,7 @@
 # Introduction
 llama-swap is a light weight, transparent proxy server that provides automatic model swapping to llama.cpp's server.
 
-Written in golang, it is very easy to install (single binary with no dependancies) and configure (single yaml file). 
+Written in golang, it is very easy to install (single binary with no dependancies) and configure (single yaml file).
 
 Download a pre-built [release](https://github.com/mostlygeek/llama-swap/releases) or build it yourself from source with `make clean all`.
 
@@ -30,6 +30,7 @@ Any OpenAI compatible server would work. llama-swap was originally designed for
   - `v1/rerank`
   - `v1/audio/speech` ([#36](https://github.com/mostlygeek/llama-swap/issues/36))
 - ✅ Multiple GPU support
+- ✅ Docker and Podman support
 - ✅ Run multiple models at once with `profiles`
 - ✅ Remote log monitoring at `/log`
 - ✅ Automatic unloading of models from GPUs after timeout
@@ -89,6 +90,15 @@ models:
     cmd: llama-server --port 9999 -m Llama-3.2-1B-Instruct-Q4_K_M.gguf -ngl 0
     unlisted: true
 
+  # Docker Support (v26.1.4+ required!)
+  "docker-llama":
+    proxy: "http://127.0.0.1:9790"
+    cmd: >
+      docker run --name dockertest
+      --init --rm -p 9790:8080 -v /mnt/nvme/models:/models
+      ghcr.io/ggerganov/llama.cpp:server
+      --model '/models/Qwen2.5-Coder-0.5B-Instruct-Q4_K_M.gguf'
+
 # profiles make it easy to managing multi model (and gpu) configurations.
 #
 # Tips:

config.example.yaml

@@ -53,6 +53,14 @@ models:
       --ctx-size 8192
       --reranking
 
+  # Docker Support (v26.1.4+ required!)
+  "dockertest":
+    proxy: "http://127.0.0.1:9790"
+    cmd: >
+      docker run --name dockertest
+      --init --rm -p 9790:8080 -v /mnt/nvme/models:/models
+      ghcr.io/ggerganov/llama.cpp:server
+      --model '/models/Qwen2.5-Coder-0.5B-Instruct-Q4_K_M.gguf'
 
   "simple":
     # example of setting environment variables

llama-swap.go

@@ -4,6 +4,8 @@ import (
 	"flag"
 	"fmt"
 	"os"
+	"os/signal"
+	"syscall"
 
 	"github.com/gin-gonic/gin"
 	"github.com/mostlygeek/llama-swap/proxy"
@@ -39,6 +41,16 @@ func main() {
 	}
 
 	proxyManager := proxy.New(config)
+
+	sigChan := make(chan os.Signal, 1)
+	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
+	go func() {
+		<-sigChan
+		fmt.Println("Shutting down llama-swap")
+		proxyManager.Shutdown()
+		os.Exit(0)
+	}()
+
 	fmt.Println("llama-swap listening on " + *listenStr)
 	if err := proxyManager.Run(*listenStr); err != nil {
 		fmt.Printf("Server error: %v\n", err)

proxy/process.go

@@ -17,14 +17,19 @@ import (
 type ProcessState string
 
 const (
-	StateStopped ProcessState = ProcessState("stopped")
-	StateReady   ProcessState = ProcessState("ready")
-	StateFailed  ProcessState = ProcessState("failed")
+	StateStopped  ProcessState = ProcessState("stopped")
+	StateStarting ProcessState = ProcessState("starting")
+	StateReady    ProcessState = ProcessState("ready")
+	StateStopping ProcessState = ProcessState("stopping")
+
+	// failed a health check on start and will not be recovered
+	StateFailed ProcessState = ProcessState("failed")
+
+	// process is shutdown and will not be restarted
+	StateShutdown ProcessState = ProcessState("shutdown")
 )
 
 type Process struct {
-	sync.Mutex
-
 	ID                 string
 	config             ModelConfig
 	cmd                *exec.Cmd
@@ -37,9 +42,17 @@ type Process struct {
 	state      ProcessState
 
 	inFlightRequests sync.WaitGroup
+
+	// used to block on multiple start() calls
+	waitStarting sync.WaitGroup
+
+	// for managing shutdown state
+	shutdownCtx    context.Context
+	shutdownCancel context.CancelFunc
 }
 
 func NewProcess(ID string, healthCheckTimeout int, config ModelConfig, logMonitor *LogMonitor) *Process {
+	ctx, cancel := context.WithCancel(context.Background())
 	return &Process{
 		ID:                 ID,
 		config:             config,
@@ -47,22 +60,88 @@ func NewProcess(ID string, healthCheckTimeout int, config ModelConfig, logMonito
 		logMonitor:         logMonitor,
 		healthCheckTimeout: healthCheckTimeout,
 		state:              StateStopped,
+		shutdownCtx:        ctx,
+		shutdownCancel:     cancel,
 	}
 }
 
-// start the process and returns when it is ready
+func (p *Process) setState(newState ProcessState) error {
+	// enforce valid state transitions
+	invalidTransition := false
+	if p.state == StateStopped {
+		// stopped -> starting
+		if newState != StateStarting {
+			invalidTransition = true
+		}
+	} else if p.state == StateStarting {
+		// starting -> ready | failed | stopping
+		if newState != StateReady && newState != StateFailed && newState != StateStopping {
+			invalidTransition = true
+		}
+	} else if p.state == StateReady {
+		// ready -> stopping
+		if newState != StateStopping {
+			invalidTransition = true
+		}
+	} else if p.state == StateStopping {
+		// stopping -> stopped | shutdown
+		if newState != StateStopped && newState != StateShutdown {
+			invalidTransition = true
+		}
+	} else if p.state == StateFailed || p.state == StateShutdown {
+		invalidTransition = true
+	}
+
+	if invalidTransition {
+		//panic(fmt.Sprintf("Invalid state transition from %s to %s", p.state, newState))
+		return fmt.Errorf("invalid state transition from %s to %s", p.state, newState)
+	}
+
+	p.state = newState
+	return nil
+}
+
+func (p *Process) CurrentState() ProcessState {
+	p.stateMutex.RLock()
+	defer p.stateMutex.RUnlock()
+	return p.state
+}
+
+// start starts the upstream command, checks the health endpoint, and sets the state to Ready
+// it is a private method because starting is automatic but stopping can be called
+// at any time.
 func (p *Process) start() error {
 
+	if p.config.Proxy == "" {
+		return fmt.Errorf("can not start(), upstream proxy missing")
+	}
+
+	// wait for the other start() to complete
+	curState := p.CurrentState()
+
+	if curState == StateReady {
+		return nil
+	}
+
+	if curState == StateStarting {
+		p.waitStarting.Wait()
+
+		if state := p.CurrentState(); state != StateReady {
+			return fmt.Errorf("start() failed current state: %v", state)
+		}
+
+		return nil
+	}
+
 	p.stateMutex.Lock()
 	defer p.stateMutex.Unlock()
 
-	if p.state == StateReady {
-		return nil
+	if err := p.setState(StateStarting); err != nil {
+		return err
 	}
 
-	if p.state == StateFailed {
-		return fmt.Errorf("process is in a failed state and can not be restarted")
-	}
+	p.waitStarting.Add(1)
+	defer p.waitStarting.Done()
 
 	args, err := p.config.SanitizedCommand()
 	if err != nil {
@@ -77,7 +156,8 @@ func (p *Process) start() error {
 	err = p.cmd.Start()
 
 	if err != nil {
-		return err
+		p.setState(StateFailed)
+		return fmt.Errorf("start() failed: %v", err)
 	}
 
 	// One of three things can happen at this stage:
@@ -86,35 +166,56 @@ func (p *Process) start() error {
 	// 3. The health check passes
 	//
 	// only in the third case will the process be considered Ready to accept
-	healthCheckContext, cancelHealthCheck := context.WithCancelCause(context.Background())
-	defer cancelHealthCheck(nil) // clean up
-	cmdWaitChan := make(chan error, 1)
-	healthCheckChan := make(chan error, 1)
+	<-time.After(250 * time.Millisecond) // give process a bit of time to start
 
-	go func() {
-		// possible cmd exits early
-		cmdWaitChan <- p.cmd.Wait()
-	}()
+	checkStartTime := time.Now()
+	maxDuration := time.Second * time.Duration(p.healthCheckTimeout)
+	checkEndpoint := strings.TrimSpace(p.config.CheckEndpoint)
 
-	go func() {
-		<-time.After(250 * time.Millisecond) // give process a bit of time to start
-		healthCheckChan <- p.checkHealthEndpoint(healthCheckContext)
-	}()
-
-	select {
-	case err := <-cmdWaitChan:
-		p.state = StateFailed
-		if err != nil {
-			err = fmt.Errorf("command [%s] %s", strings.Join(p.cmd.Args, " "), err.Error())
-		} else {
-			err = fmt.Errorf("command [%s] exited unexpected", strings.Join(p.cmd.Args, " "))
+	// a "none" means don't check for health ... I could have picked a better word :facepalm:
+	if checkEndpoint != "none" {
+		// keep default behaviour
+		if checkEndpoint == "" {
+			checkEndpoint = "/health"
 		}
-		cancelHealthCheck(err)
-		return err
-	case err := <-healthCheckChan:
+
+		proxyTo := p.config.Proxy
+		healthURL, err := url.JoinPath(proxyTo, checkEndpoint)
 		if err != nil {
-			p.state = StateFailed
-			return err
+			return fmt.Errorf("failed to create health check URL proxy=%s and checkEndpoint=%s", proxyTo, checkEndpoint)
+		}
+
+		checkDeadline, cancelHealthCheck := context.WithDeadline(
+			context.Background(),
+			checkStartTime.Add(maxDuration),
+		)
+		defer cancelHealthCheck()
+
+		// Health check loop
+	loop:
+		for {
+			select {
+			case <-checkDeadline.Done():
+				p.setState(StateFailed)
+				return fmt.Errorf("health check failed after %vs", maxDuration.Seconds())
+			case <-p.shutdownCtx.Done():
+				return errors.New("health check interrupted due to shutdown")
+			default:
+				if err := p.checkHealthEndpoint(healthURL); err == nil {
+					cancelHealthCheck()
+					break loop
+				} else {
+					if strings.Contains(err.Error(), "connection refused") {
+						endTime, _ := checkDeadline.Deadline()
+						ttl := time.Until(endTime)
+						fmt.Fprintf(p.logMonitor, "!!! Connection refused on %s, ttl %.0fs\n", healthURL, ttl.Seconds())
+					} else {
+						fmt.Fprintf(p.logMonitor, "!!! Health check error: %v\n", err)
+					}
+				}
+			}
+
+			<-time.After(time.Second)
 		}
 	}
 
@@ -141,162 +242,141 @@ func (p *Process) start() error {
 		}()
 	}
 
-	p.state = StateReady
-	return nil
+	return p.setState(StateReady)
 }
 
 func (p *Process) Stop() {
 	// wait for any inflight requests before proceeding
 	p.inFlightRequests.Wait()
-
 	p.stateMutex.Lock()
 	defer p.stateMutex.Unlock()
 
-	if p.state != StateReady {
+	// calling Stop() when state is invalid is a no-op
+	if err := p.setState(StateStopping); err != nil {
+		fmt.Fprintf(p.logMonitor, "!!! Info - Stop() err: %v\n", err)
 		return
 	}
 
-	if p.cmd == nil || p.cmd.Process == nil {
-		// this situation should never happen... but if it does just update the state
-		fmt.Fprintf(p.logMonitor, "!!! State is Ready but Command is nil.")
-		p.state = StateStopped
-		return
+	// stop the process with a graceful exit timeout
+	p.stopCommand(5 * time.Second)
+
+	if err := p.setState(StateStopped); err != nil {
+		panic(fmt.Sprintf("Stop() failed to set state to stopped: %v", err))
 	}
+}
 
-	// Pretty sure this stopping code needs some work for windows and
-	// will be a source of pain in the future.
+// Shutdown is called when llama-swap is shutting down. It will give a little bit
+// of time for any inflight requests to complete before shutting down. If the Process
+// is in the state of starting, it will cancel it and shut it down
+func (p *Process) Shutdown() {
+	// cancel anything that can be interrupted by a shutdown (ie: healthcheck)
+	p.shutdownCancel()
 
-	sigtermTimeout, cancel := context.WithTimeout(context.Background(), 5*time.Second)
-	defer cancel()
+	p.stateMutex.Lock()
+	defer p.stateMutex.Unlock()
+	p.setState(StateStopping)
+
+	// 5 seconds to stop the process
+	p.stopCommand(5 * time.Second)
+	if err := p.setState(StateShutdown); err != nil {
+		fmt.Printf("!!! Shutdown() failed to set state to shutdown: %v", err)
+	}
+	p.setState(StateShutdown)
+}
+
+// stopCommand will send a SIGTERM to the process and wait for it to exit.
+// If it does not exit within 5 seconds, it will send a SIGKILL.
+func (p *Process) stopCommand(sigtermTTL time.Duration) {
+	sigtermTimeout, cancelTimeout := context.WithTimeout(context.Background(), sigtermTTL)
+	defer cancelTimeout()
 
 	sigtermNormal := make(chan error, 1)
 	go func() {
 		sigtermNormal <- p.cmd.Wait()
 	}()
 
+	if p.cmd == nil || p.cmd.Process == nil {
+		panic("this should not happen, cmd or cmd.Process is nil")
+	}
+
 	p.cmd.Process.Signal(syscall.SIGTERM)
 
 	select {
 	case <-sigtermTimeout.Done():
-		fmt.Fprintf(p.logMonitor, "XXX Process for %s timed out waiting to stop, sending SIGKILL to PID: %d\n", p.ID, p.cmd.Process.Pid)
+		fmt.Fprintf(p.logMonitor, "!!! process [%s] timed out waiting to stop, sending KILL signal\n", p.ID)
 		p.cmd.Process.Kill()
-		p.cmd.Wait()
 	case err := <-sigtermNormal:
 		if err != nil {
-			if err.Error() != "wait: no child processes" {
-				// possible that simple-responder for testing is just not
-				// existing right, so suppress those errors.
-				fmt.Fprintf(p.logMonitor, "!!! process for %s stopped with error > %v\n", p.ID, err)
-			}
-		}
-	}
-	p.state = StateStopped
-}
-
-func (p *Process) CurrentState() ProcessState {
-	p.stateMutex.RLock()
-	defer p.stateMutex.RUnlock()
-	return p.state
-}
-
-func (p *Process) checkHealthEndpoint(ctxFromStart context.Context) error {
-	if p.config.Proxy == "" {
-		return fmt.Errorf("no upstream available to check /health")
-	}
-
-	checkEndpoint := strings.TrimSpace(p.config.CheckEndpoint)
-
-	if checkEndpoint == "none" {
-		return nil
-	}
-
-	// keep default behaviour
-	if checkEndpoint == "" {
-		checkEndpoint = "/health"
-	}
-
-	proxyTo := p.config.Proxy
-	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)
-	}
-
-	client := &http.Client{}
-	startTime := time.Now()
-
-	for {
-		req, err := http.NewRequest("GET", healthURL, nil)
-		if err != nil {
-			return err
-		}
-
-		ctx, cancel := context.WithTimeout(ctxFromStart, time.Second)
-		defer cancel()
-		req = req.WithContext(ctx)
-		resp, err := client.Do(req)
-
-		ttl := (maxDuration - time.Since(startTime)).Seconds()
-
-		if err != nil {
-			// check if the context was cancelled
-			select {
-			case <-ctx.Done():
-				err := context.Cause(ctx)
-				if !errors.Is(err, context.DeadlineExceeded) {
-					return err
+			if errno, ok := err.(syscall.Errno); ok {
+				fmt.Fprintf(p.logMonitor, "!!! process [%s] errno >> %v\n", p.ID, errno)
+			} else if exitError, ok := err.(*exec.ExitError); ok {
+				if strings.Contains(exitError.String(), "signal: terminated") {
+					fmt.Fprintf(p.logMonitor, "!!! process [%s] stopped OK\n", p.ID)
+				} else if strings.Contains(exitError.String(), "signal: interrupt") {
+					fmt.Fprintf(p.logMonitor, "!!! process [%s] interrupted OK\n", p.ID)
+				} else {
+					fmt.Fprintf(p.logMonitor, "!!! process [%s] ExitError >> %v, exit code: %d\n", p.ID, exitError, exitError.ExitCode())
 				}
-			default:
-			}
 
-			// wait a bit longer for TCP connection issues
-			if strings.Contains(err.Error(), "connection refused") {
-				fmt.Fprintf(p.logMonitor, "Connection refused on %s, ttl %.0fs\n", healthURL, ttl)
-				time.Sleep(5 * time.Second)
 			} else {
-				time.Sleep(time.Second)
+				fmt.Fprintf(p.logMonitor, "!!! process [%s] exited >> %v\n", p.ID, err)
 			}
-
-			if ttl < 0 {
-				return fmt.Errorf("failed to check health from: %s", healthURL)
-			}
-
-			continue
 		}
-
-		defer resp.Body.Close()
-		if resp.StatusCode == http.StatusOK {
-			return nil
-		}
-
-		if ttl < 0 {
-			return fmt.Errorf("failed to check health from: %s", healthURL)
-		}
-
-		time.Sleep(time.Second)
 	}
 }
 
+func (p *Process) checkHealthEndpoint(healthURL string) error {
+
+	client := &http.Client{
+		Timeout: 500 * time.Millisecond,
+	}
+
+	req, err := http.NewRequest("GET", healthURL, nil)
+	if err != nil {
+		return err
+	}
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	// got a response but it was not an OK
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("status code: %d", resp.StatusCode)
+	}
+
+	return nil
+}
+
 func (p *Process) ProxyRequest(w http.ResponseWriter, r *http.Request) {
 
-	p.inFlightRequests.Add(1)
+	// prevent new requests from being made while stopping or irrecoverable
+	currentState := p.CurrentState()
+	if currentState == StateFailed || currentState == StateShutdown || currentState == StateStopping {
+		http.Error(w, fmt.Sprintf("Process can not ProxyRequest, state is %s", currentState), http.StatusServiceUnavailable)
+		return
+	}
 
+	p.inFlightRequests.Add(1)
 	defer func() {
 		p.lastRequestHandled = time.Now()
 		p.inFlightRequests.Done()
 	}()
 
+	// start the process on demand
 	if p.CurrentState() != StateReady {
 		if err := p.start(); err != nil {
 			errstr := fmt.Sprintf("unable to start process: %s", err)
-			http.Error(w, errstr, http.StatusInternalServerError)
+			http.Error(w, errstr, http.StatusBadGateway)
 			return
 		}
 	}
 
 	proxyTo := p.config.Proxy
 	client := &http.Client{}
-	req, err := http.NewRequest(r.Method, proxyTo+r.URL.String(), r.Body)
+	req, err := http.NewRequestWithContext(r.Context(), r.Method, proxyTo+r.URL.String(), r.Body)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return

proxy/process_test.go

@@ -48,6 +48,33 @@ func TestProcess_AutomaticallyStartsUpstream(t *testing.T) {
 	}
 }
 
+// TestProcess_WaitOnMultipleStarts tests that multiple concurrent requests
+// are all handled successfully, even though they all may ask for the process to .start()
+func TestProcess_WaitOnMultipleStarts(t *testing.T) {
+
+	logMonitor := NewLogMonitorWriter(io.Discard)
+	expectedMessage := "testing91931"
+	config := getTestSimpleResponderConfig(expectedMessage)
+
+	process := NewProcess("test-process", 5, config, logMonitor)
+	defer process.Stop()
+
+	var wg sync.WaitGroup
+	for i := 0; i < 5; i++ {
+		wg.Add(1)
+		go func(reqID int) {
+			defer wg.Done()
+			req := httptest.NewRequest("GET", "/test", nil)
+			w := httptest.NewRecorder()
+			process.ProxyRequest(w, req)
+			assert.Equal(t, http.StatusOK, w.Code, "Worker %d got wrong HTTP code", reqID)
+			assert.Contains(t, w.Body.String(), expectedMessage, "Worker %d got wrong message", reqID)
+		}(i)
+	}
+	wg.Wait()
+	assert.Equal(t, StateReady, process.CurrentState())
+}
+
 // test that the automatic start returns the expected error type
 func TestProcess_BrokenModelConfig(t *testing.T) {
 	// Create a process configuration
@@ -58,13 +85,17 @@ func TestProcess_BrokenModelConfig(t *testing.T) {
 	}
 
 	process := NewProcess("broken", 1, config, NewLogMonitor())
-	defer process.Stop()
 
 	req := httptest.NewRequest("GET", "/", nil)
 	w := httptest.NewRecorder()
 	process.ProxyRequest(w, req)
-	assert.Equal(t, http.StatusInternalServerError, w.Code)
+	assert.Equal(t, http.StatusBadGateway, w.Code)
 	assert.Contains(t, w.Body.String(), "unable to start process")
+
+	w = httptest.NewRecorder()
+	process.ProxyRequest(w, req)
+	assert.Equal(t, http.StatusServiceUnavailable, w.Code)
+	assert.Contains(t, w.Body.String(), "Process can not ProxyRequest, state is failed")
 }
 
 func TestProcess_UnloadAfterTTL(t *testing.T) {
@@ -190,3 +221,85 @@ func TestProcess_HTTPRequestsHaveTimeToFinish(t *testing.T) {
 		assert.Equal(t, key, result)
 	}
 }
+
+func TestSetState(t *testing.T) {
+	tests := []struct {
+		name           string
+		currentState   ProcessState
+		newState       ProcessState
+		expectedError  error
+		expectedResult ProcessState
+	}{
+		{"Stopped to Starting", StateStopped, StateStarting, nil, StateStarting},
+		{"Starting to Ready", StateStarting, StateReady, nil, StateReady},
+		{"Starting to Failed", StateStarting, StateFailed, nil, StateFailed},
+		{"Starting to Stopping", StateStarting, StateStopping, nil, StateStopping},
+		{"Ready to Stopping", StateReady, StateStopping, nil, StateStopping},
+		{"Stopping to Stopped", StateStopping, StateStopped, nil, StateStopped},
+		{"Stopping to Shutdown", StateStopping, StateShutdown, nil, StateShutdown},
+		{"Stopped to Ready", StateStopped, StateReady, fmt.Errorf("invalid state transition from stopped to ready"), StateStopped},
+		{"Starting to Stopped", StateStarting, StateStopped, fmt.Errorf("invalid state transition from starting to stopped"), StateStarting},
+		{"Ready to Starting", StateReady, StateStarting, fmt.Errorf("invalid state transition from ready to starting"), StateReady},
+		{"Ready to Failed", StateReady, StateFailed, fmt.Errorf("invalid state transition from ready to failed"), StateReady},
+		{"Stopping to Ready", StateStopping, StateReady, fmt.Errorf("invalid state transition from stopping to ready"), StateStopping},
+		{"Failed to Stopped", StateFailed, StateStopped, fmt.Errorf("invalid state transition from failed to stopped"), StateFailed},
+		{"Failed to Starting", StateFailed, StateStarting, fmt.Errorf("invalid state transition from failed to starting"), StateFailed},
+		{"Shutdown to Stopped", StateShutdown, StateStopped, fmt.Errorf("invalid state transition from shutdown to stopped"), StateShutdown},
+		{"Shutdown to Starting", StateShutdown, StateStarting, fmt.Errorf("invalid state transition from shutdown to starting"), StateShutdown},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			p := &Process{
+				state: test.currentState,
+			}
+
+			err := p.setState(test.newState)
+			if err != nil && test.expectedError == nil {
+				t.Errorf("Unexpected error: %v", err)
+			} else if err == nil && test.expectedError != nil {
+				t.Errorf("Expected error: %v, but got none", test.expectedError)
+			} else if err != nil && test.expectedError != nil {
+				if err.Error() != test.expectedError.Error() {
+					t.Errorf("Expected error: %v, got: %v", test.expectedError, err)
+				}
+			}
+
+			if p.state != test.expectedResult {
+				t.Errorf("Expected state: %v, got: %v", test.expectedResult, p.state)
+			}
+		})
+	}
+}
+
+func TestProcess_ShutdownInterruptsHealthCheck(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping long shutdown test")
+	}
+
+	logMonitor := NewLogMonitorWriter(io.Discard)
+	expectedMessage := "testing91931"
+
+	// make a config where the healthcheck will always fail because port is wrong
+	config := getTestSimpleResponderConfigPort(expectedMessage, 9999)
+	config.Proxy = "http://localhost:9998/test"
+
+	healthCheckTTLSeconds := 30
+	process := NewProcess("test-process", healthCheckTTLSeconds, config, logMonitor)
+
+	// start a goroutine to simulate a shutdown
+	var wg sync.WaitGroup
+	go func() {
+		defer wg.Done()
+		<-time.After(time.Second * 2)
+		process.Shutdown()
+	}()
+	wg.Add(1)
+
+	// start the process, this is a blocking call
+	err := process.start()
+
+	wg.Wait()
+	assert.ErrorContains(t, err, "health check interrupted due to shutdown")
+	assert.Equal(t, StateShutdown, process.CurrentState())
+}

proxy/proxymanager.go

@@ -69,6 +69,19 @@ func New(config *Config) *ProxyManager {
 		})
 	}
 
+	// see: https://github.com/mostlygeek/llama-swap/issues/42
+	// respond with permissive OPTIONS for any endpoint
+	pm.ginEngine.Use(func(c *gin.Context) {
+		if c.Request.Method == "OPTIONS" {
+			c.Header("Access-Control-Allow-Origin", "*")
+			c.Header("Access-Control-Allow-Methods", "GET, POST, OPTIONS")
+			c.Header("Access-Control-Allow-Headers", "Content-Type, Authorization")
+			c.AbortWithStatus(204)
+			return
+		}
+		c.Next()
+	})
+
 	// Set up routes using the Gin engine
 	pm.ginEngine.POST("/v1/chat/completions", pm.proxyOAIHandler)
 	// Support legacy /v1/completions api, see issue #12
@@ -143,13 +156,38 @@ func (pm *ProxyManager) stopProcesses() {
 		return
 	}
 
+	// stop Processes in parallel
+	var wg sync.WaitGroup
 	for _, process := range pm.currentProcesses {
-		process.Stop()
+		wg.Add(1)
+		go func(process *Process) {
+			defer wg.Done()
+			process.Stop()
+		}(process)
 	}
+	wg.Wait()
 
 	pm.currentProcesses = make(map[string]*Process)
 }
 
+// Shutdown is called to shutdown all upstream processes
+// when llama-swap is shutting down.
+func (pm *ProxyManager) Shutdown() {
+	pm.Lock()
+	defer pm.Unlock()
+
+	// shutdown process in parallel
+	var wg sync.WaitGroup
+	for _, process := range pm.currentProcesses {
+		wg.Add(1)
+		go func(process *Process) {
+			defer wg.Done()
+			process.Shutdown()
+		}(process)
+	}
+	wg.Wait()
+}
+
 func (pm *ProxyManager) listModelsHandler(c *gin.Context) {
 	data := []interface{}{}
 	for id, modelConfig := range pm.config.Models {

proxy/proxymanager_test.go

@@ -254,3 +254,53 @@ func TestProxyManager_ProfileNonMember(t *testing.T) {
 		assert.Equal(t, http.StatusNotFound, w.Code)
 	}
 }
+
+func TestProxyManager_Shutdown(t *testing.T) {
+	// make broken model configurations
+	model1Config := getTestSimpleResponderConfigPort("model1", 9991)
+	model1Config.Proxy = "http://localhost:10001/"
+
+	model2Config := getTestSimpleResponderConfigPort("model2", 9992)
+	model2Config.Proxy = "http://localhost:10002/"
+
+	model3Config := getTestSimpleResponderConfigPort("model3", 9993)
+	model3Config.Proxy = "http://localhost:10003/"
+
+	config := &Config{
+		HealthCheckTimeout: 15,
+		Profiles: map[string][]string{
+			"test": {"model1", "model2", "model3"},
+		},
+		Models: map[string]ModelConfig{
+			"model1": model1Config,
+			"model2": model2Config,
+			"model3": model3Config,
+		},
+	}
+
+	proxy := New(config)
+
+	// Start all the processes
+	var wg sync.WaitGroup
+	for _, modelName := range []string{"test:model1", "test:model2", "test:model3"} {
+		wg.Add(1)
+		go func(modelName string) {
+			defer wg.Done()
+			reqBody := fmt.Sprintf(`{"model":"%s"}`, modelName)
+			req := httptest.NewRequest("POST", "/v1/chat/completions", bytes.NewBufferString(reqBody))
+			w := httptest.NewRecorder()
+
+			// send a request to trigger the proxy to load
+			proxy.HandlerFunc(w, req)
+			assert.Equal(t, http.StatusBadGateway, w.Code)
+			assert.Contains(t, w.Body.String(), "health check interrupted due to shutdown")
+			//fmt.Println(w.Code, w.Body.String())
+		}(modelName)
+	}
+
+	go func() {
+		<-time.After(time.Second)
+		proxy.Shutdown()
+	}()
+	wg.Wait()
+}