proxy,proxy/config: add global TTL feature (#554)

Add a new configuration parameter globalTTL that all models will
inherit. The default value is 0 which matches the currently
functionality to never automatically unload a model.

The model.ttl's default has changed to -1, which means use the global
TTL value. Any model.ttl >=0 is now value with 0 meaning never unload.
This allows a model to override a globalTTL > 0 and be configured to
never unload.

Fixes #459
Closes #512

proxy/config/config.go

@@ -124,6 +124,7 @@ type Config struct {
 	LogToStdout        string                 `yaml:"logToStdout"`
 	MetricsMaxInMemory int                    `yaml:"metricsMaxInMemory"`
 	CaptureBuffer      int                    `yaml:"captureBuffer"`
+	GlobalTTL          int                    `yaml:"globalTTL"`
 	Models             map[string]ModelConfig `yaml:"models"` /* key is model ID */
 	Profiles           map[string][]string    `yaml:"profiles"`
 	Groups             map[string]GroupConfig `yaml:"groups"` /* key is group ID */
@@ -203,6 +204,7 @@ func LoadConfigFromReader(r io.Reader) (Config, error) {
 		LogToStdout:        LogToStdoutProxy,
 		MetricsMaxInMemory: 1000,
 		CaptureBuffer:      5,
+		GlobalTTL:          0,
 	}
 	if err = yaml.Unmarshal([]byte(yamlStr), &config); err != nil {
 		return Config{}, err
@@ -216,6 +218,10 @@ func LoadConfigFromReader(r io.Reader) (Config, error) {
 		return Config{}, fmt.Errorf("startPort must be greater than 1")
 	}
 
+	if config.GlobalTTL < 0 {
+		return Config{}, fmt.Errorf("globalTTL must be >= 0")
+	}
+
 	switch config.LogToStdout {
 	case LogToStdoutProxy, LogToStdoutUpstream, LogToStdoutBoth, LogToStdoutNone:
 	default:
@@ -255,6 +261,15 @@ func LoadConfigFromReader(r io.Reader) (Config, error) {
 		modelConfig.Cmd = StripComments(modelConfig.Cmd)
 		modelConfig.CmdStop = StripComments(modelConfig.CmdStop)
 
+		// set model TTL to globalTTL it is the default value
+		if modelConfig.UnloadAfter == MODEL_CONFIG_DEFAULT_TTL {
+			modelConfig.UnloadAfter = config.GlobalTTL
+		}
+
+		if modelConfig.UnloadAfter < 0 {
+			return Config{}, fmt.Errorf("model %s: invalid TTL value %d", modelId, modelConfig.UnloadAfter)
+		}
+
 		// Validate model macros
 		for _, macro := range modelConfig.Macros {
 			if err = validateMacro(macro.Name, macro.Value); err != nil {

proxy/config/config_test.go

@@ -848,6 +848,71 @@ func TestConfig_APIKeys_EnvMacros(t *testing.T) {
 	})
 }
 
+func TestConfig_GlobalTTL(t *testing.T) {
+	t.Run("globalTTL sets default for models", func(t *testing.T) {
+		content := `
+globalTTL: 300
+models:
+  model1:
+    cmd: server --port ${PORT}
+`
+		config, err := LoadConfigFromReader(strings.NewReader(content))
+		assert.NoError(t, err)
+		assert.Equal(t, 300, config.GlobalTTL)
+		assert.Equal(t, 300, config.Models["model1"].UnloadAfter)
+	})
+
+	t.Run("model ttl=0 overrides globalTTL", func(t *testing.T) {
+		content := `
+globalTTL: 300
+models:
+  model1:
+    cmd: server --port ${PORT}
+    ttl: 0
+`
+		config, err := LoadConfigFromReader(strings.NewReader(content))
+		assert.NoError(t, err)
+		assert.Equal(t, 0, config.Models["model1"].UnloadAfter)
+	})
+
+	t.Run("model explicit ttl overrides globalTTL", func(t *testing.T) {
+		content := `
+globalTTL: 300
+models:
+  model1:
+    cmd: server --port ${PORT}
+    ttl: 600
+`
+		config, err := LoadConfigFromReader(strings.NewReader(content))
+		assert.NoError(t, err)
+		assert.Equal(t, 600, config.Models["model1"].UnloadAfter)
+	})
+
+	t.Run("globalTTL defaults to 0", func(t *testing.T) {
+		content := `
+models:
+  model1:
+    cmd: server --port ${PORT}
+`
+		config, err := LoadConfigFromReader(strings.NewReader(content))
+		assert.NoError(t, err)
+		assert.Equal(t, 0, config.GlobalTTL)
+		assert.Equal(t, 0, config.Models["model1"].UnloadAfter)
+	})
+
+	t.Run("negative globalTTL rejected", func(t *testing.T) {
+		content := `
+globalTTL: -1
+models:
+  model1:
+    cmd: server --port ${PORT}
+`
+		_, err := LoadConfigFromReader(strings.NewReader(content))
+		assert.Error(t, err)
+		assert.Contains(t, err.Error(), "globalTTL must be >= 0")
+	})
+}
+
 func TestConfig_EnvMacros(t *testing.T) {
 	t.Run("basic env substitution in cmd", func(t *testing.T) {
 		t.Setenv("TEST_MODEL_PATH", "/opt/models")

proxy/config/model_config.go

@@ -5,6 +5,10 @@ import (
 	"runtime"
 )
 
+const (
+	MODEL_CONFIG_DEFAULT_TTL = -1
+)
+
 type ModelConfig struct {
 	Cmd           string   `yaml:"cmd"`
 	CmdStop       string   `yaml:"cmdStop"`
@@ -47,7 +51,7 @@ func (m *ModelConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
 		Aliases:          []string{},
 		Env:              []string{},
 		CheckEndpoint:    "/health",
-		UnloadAfter:      0,
+		UnloadAfter:      MODEL_CONFIG_DEFAULT_TTL, // use GlobalTTL
 		Unlisted:         false,
 		UseModelName:     "",
 		ConcurrencyLimit: 0,

proxy/process_test.go

@@ -117,12 +117,12 @@ func TestProcess_UnloadAfterTTL(t *testing.T) {
 	}
 
 	expectedMessage := "I_sense_imminent_danger"
-	config := getTestSimpleResponderConfig(expectedMessage)
-	assert.Equal(t, 0, config.UnloadAfter)
-	config.UnloadAfter = 3 // seconds
-	assert.Equal(t, 3, config.UnloadAfter)
+	conf := getTestSimpleResponderConfig(expectedMessage)
+	assert.Equal(t, config.MODEL_CONFIG_DEFAULT_TTL, conf.UnloadAfter)
+	conf.UnloadAfter = 3 // seconds
+	assert.Equal(t, 3, conf.UnloadAfter)
 
-	process := NewProcess("ttl_test", 2, config, debugLogger, debugLogger)
+	process := NewProcess("ttl_test", 2, conf, debugLogger, debugLogger)
 	defer process.Stop()
 
 	// this should take 4 seconds
@@ -159,12 +159,12 @@ func TestProcess_LowTTLValue(t *testing.T) {
 		t.Skip("skipping test, edit process_test.go to run it ")
 	}
 
-	config := getTestSimpleResponderConfig("fast_ttl")
-	assert.Equal(t, 0, config.UnloadAfter)
-	config.UnloadAfter = 1 // second
-	assert.Equal(t, 1, config.UnloadAfter)
+	conf := getTestSimpleResponderConfig("fast_ttl")
+	assert.Equal(t, config.MODEL_CONFIG_DEFAULT_TTL, conf.UnloadAfter)
+	conf.UnloadAfter = 1 // second
+	assert.Equal(t, 1, conf.UnloadAfter)
 
-	process := NewProcess("ttl", 2, config, debugLogger, debugLogger)
+	process := NewProcess("ttl", 2, conf, debugLogger, debugLogger)
 	defer process.Stop()
 
 	for i := 0; i < 100; i++ {

proxy/proxymanager_test.go

@@ -730,7 +730,7 @@ func TestProxyManager_RunningEndpoint(t *testing.T) {
 		// Verify extended fields are present
 		assert.NotEmpty(t, response.Running[0].Cmd, "cmd should be populated")
 		assert.NotEmpty(t, response.Running[0].Proxy, "proxy should be populated")
-		assert.Equal(t, 0, response.Running[0].TTL, "ttl should default to 0")
+		assert.Equal(t, -1, response.Running[0].TTL, "ttl should default to -1 (use globalTTL)")
 	})
 }