Add barebones but working implementation of model preload (#209, #235)

Add barebones but working implementation of model preload

* add config test for Preload hook
* improve TestProxyManager_StartupHooks
* docs for new hook configuration
* add a .dev to .gitignore

.gitignore

@@ -4,3 +4,4 @@ build/
 dist/
 .vscode
 .DS_Store
+.dev/

README.md

@@ -31,8 +31,9 @@ Written in golang, it is very easy to install (single binary with no dependencie
 - ✅ Run multiple models at once with `Groups` ([#107](https://github.com/mostlygeek/llama-swap/issues/107))
 - ✅ Automatic unloading of models after timeout by setting a `ttl`
 - ✅ Use any local OpenAI compatible server (llama.cpp, vllm, tabbyAPI, etc)
-- ✅ Docker and Podman support
+- ✅ Reliable Docker and Podman support with `cmdStart` and `cmdStop`
 - ✅ Full control over server settings per model
+- ✅ Preload models on startup with `hooks` ([#235](https://github.com/mostlygeek/llama-swap/pull/235))
 
 ## How does llama-swap work?
 

config.example.yaml

@@ -1,6 +1,13 @@
 # llama-swap YAML configuration example
 # -------------------------------------
 #
+# 💡 Tip - Use an LLM with this file!
+# ====================================
+#  This example configuration is written to be LLM friendly! Try
+#  copying this file into an LLM and asking it to explain or generate
+#  sections for you.
+# ====================================
+#
 # - Below are all the available configuration options for llama-swap.
 # - Settings with a default value, or noted as optional can be omitted.
 # - Settings that are marked required must be in your configuration file
@@ -207,3 +214,19 @@ groups:
       - "forever-modelA"
       - "forever-modelB"
       - "forever-modelc"
+
+# hooks: a dictionary of event triggers and actions
+# - optional, default: empty dictionary
+# - the only supported hook is on_startup
+hooks:
+  # on_startup: a dictionary of actions to perform on startup
+  # - optional, default: empty dictionar
+  # - the only supported action is preload
+  on_startup:
+        # preload: a list of model ids to load on startup
+        # - optional, default: empty list
+        # - model names must match keys in the models sections
+        # - when preloading multiple models at once, define a group
+        #   otherwise models will be loaded and swapped out
+    preload:
+      - "llama"

proxy/config.go

@@ -138,6 +138,14 @@ func (c *GroupConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	return nil
 }
 
+type HooksConfig struct {
+	OnStartup HookOnStartup `yaml:"on_startup"`
+}
+
+type HookOnStartup struct {
+	Preload []string `yaml:"preload"`
+}
+
 type Config struct {
 	HealthCheckTimeout int                    `yaml:"healthCheckTimeout"`
 	LogRequests        bool                   `yaml:"logRequests"`
@@ -155,6 +163,9 @@ type Config struct {
 
 	// automatic port assignments
 	StartPort int `yaml:"startPort"`
+
+	// hooks, see: #209
+	Hooks HooksConfig `yaml:"hooks"`
 }
 
 func (c *Config) RealModelName(search string) (string, bool) {
@@ -330,6 +341,22 @@ func LoadConfigFromReader(r io.Reader) (Config, error) {
 		}
 	}
 
+	// clean up hooks preload
+	if len(config.Hooks.OnStartup.Preload) > 0 {
+		var toPreload []string
+		for _, modelID := range config.Hooks.OnStartup.Preload {
+			modelID = strings.TrimSpace(modelID)
+			if modelID == "" {
+				continue
+			}
+			if real, found := config.RealModelName(modelID); found {
+				toPreload = append(toPreload, real)
+			}
+		}
+
+		config.Hooks.OnStartup.Preload = toPreload
+	}
+
 	return config, nil
 }
 

proxy/config_posix_test.go

@@ -100,6 +100,9 @@ func TestConfig_LoadPosix(t *testing.T) {
 	content := `
 macros:
   svr-path: "path/to/server"
+hooks:
+  on_startup:
+    preload: ["model1", "model2"]
 models:
   model1:
     cmd: path/to/cmd --arg1 one
@@ -163,6 +166,11 @@ groups:
 		Macros: map[string]string{
 			"svr-path": "path/to/server",
 		},
+		Hooks: HooksConfig{
+			OnStartup: HookOnStartup{
+				Preload: []string{"model1", "model2"},
+			},
+		},
 		Models: map[string]ModelConfig{
 			"model1": {
 				Cmd:           "path/to/cmd --arg1 one",

proxy/discardWriter.go

@@ -0,0 +1,27 @@
+package proxy
+
+import "net/http"
+
+// Custom discard writer that implements http.ResponseWriter but just discards everything
+type DiscardWriter struct {
+	header http.Header
+	status int
+}
+
+func (w *DiscardWriter) Header() http.Header {
+	if w.header == nil {
+		w.header = make(http.Header)
+	}
+	return w.header
+}
+
+func (w *DiscardWriter) Write(data []byte) (int, error) {
+	return len(data), nil
+}
+
+func (w *DiscardWriter) WriteHeader(code int) {
+	w.status = code
+}
+
+// Satisfy the http.Flusher interface for streaming responses
+func (w *DiscardWriter) Flush() {}

proxy/events.go

@@ -7,6 +7,7 @@ const ChatCompletionStatsEventID = 0x02
 const ConfigFileChangedEventID = 0x03
 const LogDataEventID = 0x04
 const TokenMetricsEventID = 0x05
+const ModelPreloadedEventID = 0x06
 
 type ProcessStateChangeEvent struct {
 	ProcessName string
@@ -48,3 +49,12 @@ type LogDataEvent struct {
 func (e LogDataEvent) Type() uint32 {
 	return LogDataEventID
 }
+
+type ModelPreloadedEvent struct {
+	ModelName string
+	Success   bool
+}
+
+func (e ModelPreloadedEvent) Type() uint32 {
+	return ModelPreloadedEventID
+}

proxy/helpers_test.go

@@ -16,6 +16,7 @@ var (
 	nextTestPort        int = 12000
 	portMutex           sync.Mutex
 	testLogger          = NewLogMonitorWriter(os.Stdout)
+	simpleResponderPath = getSimpleResponderPath()
 )
 
 // Check if the binary exists
@@ -69,13 +70,11 @@ func getTestSimpleResponderConfig(expectedMessage string) ModelConfig {
 }
 
 func getTestSimpleResponderConfigPort(expectedMessage string, port int) ModelConfig {
-	binaryPath := getSimpleResponderPath()
-
 	// Create a YAML string with just the values we want to set
 	yamlStr := fmt.Sprintf(`
 cmd: '%s --port %d --silent --respond %s'
 proxy: "http://127.0.0.1:%d"
-`, binaryPath, port, expectedMessage, port)
+`, simpleResponderPath, port, expectedMessage, port)
 
 	var cfg ModelConfig
 	if err := yaml.Unmarshal([]byte(yamlStr), &cfg); err != nil {

proxy/proxymanager.go

@@ -15,6 +15,7 @@ import (
 	"time"
 
 	"github.com/gin-gonic/gin"
+	"github.com/mostlygeek/llama-swap/event"
 	"github.com/tidwall/gjson"
 	"github.com/tidwall/sjson"
 )
@@ -96,6 +97,35 @@ func New(config Config) *ProxyManager {
 	}
 
 	pm.setupGinEngine()
+
+	// run any startup hooks
+	if len(config.Hooks.OnStartup.Preload) > 0 {
+		// do it in the background, don't block startup -- not sure if good idea yet
+		go func() {
+			discardWriter := &DiscardWriter{}
+			for _, realModelName := range config.Hooks.OnStartup.Preload {
+				proxyLogger.Infof("Preloading model: %s", realModelName)
+				processGroup, _, err := pm.swapProcessGroup(realModelName)
+
+				if err != nil {
+					event.Emit(ModelPreloadedEvent{
+						ModelName: realModelName,
+						Success:   false,
+					})
+					proxyLogger.Errorf("Failed to preload model %s: %v", realModelName, err)
+					continue
+				} else {
+					req, _ := http.NewRequest("GET", "/", nil)
+					processGroup.ProxyRequest(realModelName, discardWriter, req)
+					event.Emit(ModelPreloadedEvent{
+						ModelName: realModelName,
+						Success:   true,
+					})
+				}
+			}
+		}()
+	}
+
 	return pm
 }
 

proxy/proxymanager_test.go

@@ -14,6 +14,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/mostlygeek/llama-swap/event"
 	"github.com/stretchr/testify/assert"
 	"github.com/tidwall/gjson"
 )
@@ -832,3 +833,62 @@ func TestProxyManager_HealthEndpoint(t *testing.T) {
 	assert.Equal(t, http.StatusOK, rec.Code)
 	assert.Equal(t, "OK", rec.Body.String())
 }
+
+func TestProxyManager_StartupHooks(t *testing.T) {
+
+	// using real YAML as the configuration has gotten more complex
+	// is the right approach as LoadConfigFromReader() does a lot more
+	// than parse YAML now. Eventually migrate all tests to use this approach
+	configStr := strings.Replace(`
+logLevel: error
+hooks:
+  on_startup:
+    preload:
+      - model1
+      - model2
+groups:
+  preloadTestGroup:
+    swap: false
+    members:
+       - model1
+       - model2
+models:
+  model1:
+    cmd: ${simpleresponderpath} --port ${PORT} --silent --respond model1
+  model2:
+      cmd: ${simpleresponderpath} --port ${PORT} --silent --respond model2
+`, "${simpleresponderpath}", simpleResponderPath, -1)
+
+	// Create a test model configuration
+	config, err := LoadConfigFromReader(strings.NewReader(configStr))
+	if !assert.NoError(t, err, "Invalid configuration") {
+		return
+	}
+
+	preloadChan := make(chan ModelPreloadedEvent, 2) // buffer for 2 expected events
+
+	unsub := event.On(func(e ModelPreloadedEvent) {
+		preloadChan <- e
+	})
+
+	defer unsub()
+
+	// Create the proxy which should trigger preloading
+	proxy := New(config)
+	defer proxy.StopProcesses(StopWaitForInflightRequest)
+
+	for i := 0; i < 2; i++ {
+		select {
+		case <-preloadChan:
+		case <-time.After(5 * time.Second):
+			t.Fatal("timed out waiting for models to preload")
+		}
+	}
+	// make sure they are both loaded
+	_, foundGroup := proxy.processGroups["preloadTestGroup"]
+	if !assert.True(t, foundGroup, "preloadTestGroup should exist") {
+		return
+	}
+	assert.Equal(t, StateReady, proxy.processGroups["preloadTestGroup"].processes["model1"].CurrentState())
+	assert.Equal(t, StateReady, proxy.processGroups["preloadTestGroup"].processes["model2"].CurrentState())
+}