Add stopCmd for custom stopping instructions (#136)

Allow configuration of how a model is stopped before swapping. Setting `cmdStop` in the configuration will override the default behaviour and enables better integration with other process/container managers like docker or podman.

README.md

@@ -46,14 +46,14 @@ llama-swap's configuration is purposefully simple.
 models:
   "qwen2.5":
     proxy: "http://127.0.0.1:9999"
-    cmd: >
+    cmd: |
       /app/llama-server
       -hf bartowski/Qwen2.5-0.5B-Instruct-GGUF:Q4_K_M
       --port 9999
 
   "smollm2":
     proxy: "http://127.0.0.1:9999"
-    cmd: >
+    cmd: |
       /app/llama-server
       -hf bartowski/SmolLM2-135M-Instruct-GGUF:Q4_K_M
       --port 9999
@@ -82,7 +82,7 @@ startPort: 10001
 models:
   "llama":
     # multiline for readability
-    cmd: >
+    cmd: |
       llama-server --port 8999
       --model path/to/Qwen2.5-1.5B-Instruct-Q4_K_M.gguf
 
@@ -123,12 +123,16 @@ models:
   # Docker Support (v26.1.4+ required!)
   "docker-llama":
     proxy: "http://127.0.0.1:${PORT}"
-    cmd: >
+    cmd: |
       docker run --name dockertest
       --init --rm -p ${PORT}:8080 -v /mnt/nvme/models:/models
       ghcr.io/ggerganov/llama.cpp:server
       --model '/models/Qwen2.5-Coder-0.5B-Instruct-Q4_K_M.gguf'
 
+    # use a custom command to stop the model when swapping. By default
+    # this is SIGTERM on POSIX systems, and taskkill on Windows systems
+    cmdStop: docker stop dockertest
+
 # Groups provide advanced controls over model swapping behaviour. Using groups
 # some models can be kept loaded indefinitely, while others are swapped out.
 #

config.example.yaml

@@ -15,7 +15,7 @@ groups:
 
 models:
   "llama":
-    cmd: >
+    cmd: |
       models/llama-server-osx
       --port ${PORT}
       -m models/Llama-3.2-1B-Instruct-Q4_0.gguf
@@ -38,7 +38,7 @@ models:
   # Embedding example with Nomic
   # https://huggingface.co/nomic-ai/nomic-embed-text-v1.5-GGUF
   "nomic":
-    cmd: >
+    cmd: |
       models/llama-server-osx --port ${PORT}
       -m models/nomic-embed-text-v1.5.Q8_0.gguf
       --ctx-size 8192
@@ -51,7 +51,7 @@ models:
   # Reranking example with bge-reranker
   # https://huggingface.co/gpustack/bge-reranker-v2-m3-GGUF
   "bge-reranker":
-    cmd: >
+    cmd: |
       models/llama-server-osx --port ${PORT}
       -m models/bge-reranker-v2-m3-Q4_K_M.gguf
       --ctx-size 8192
@@ -59,7 +59,7 @@ models:
 
   # Docker Support (v26.1.4+ required!)
   "dockertest":
-    cmd: >
+    cmd: |
       docker run --name dockertest
       --init --rm -p ${PORT}:8080 -v /mnt/nvme/models:/models
       ghcr.io/ggerganov/llama.cpp:server

proxy/config.go

@@ -17,6 +17,7 @@ const DEFAULT_GROUP_ID = "(default)"
 
 type ModelConfig struct {
 	Cmd           string   `yaml:"cmd"`
+	CmdStop       string   `yaml:"cmdStop"`
 	Proxy         string   `yaml:"proxy"`
 	Aliases       []string `yaml:"aliases"`
 	Env           []string `yaml:"env"`
@@ -135,7 +136,6 @@ func LoadConfigFromReader(r io.Reader) (Config, error) {
 		}
 	}
 
-	// iterate over the models and replace any ${PORT} with the next available port
 	// Get and sort all model IDs first, makes testing more consistent
 	modelIds := make([]string, 0, len(config.Models))
 	for modelId := range config.Models {
@@ -143,10 +143,10 @@ func LoadConfigFromReader(r io.Reader) (Config, error) {
 	}
 	sort.Strings(modelIds) // This guarantees stable iteration order
 
-	// iterate over the sorted models
 	nextPort := config.StartPort
 	for _, modelId := range modelIds {
 		modelConfig := config.Models[modelId]
+		// iterate over the models and replace any ${PORT} with the next available port
 		if strings.Contains(modelConfig.Cmd, "${PORT}") {
 			modelConfig.Cmd = strings.ReplaceAll(modelConfig.Cmd, "${PORT}", strconv.Itoa(nextPort))
 			if modelConfig.Proxy == "" {
@@ -160,6 +160,7 @@ func LoadConfigFromReader(r io.Reader) (Config, error) {
 			return Config{}, fmt.Errorf("model %s requires a proxy value when not using automatic ${PORT}", modelId)
 		}
 	}
+
 	config = AddDefaultGroupToConfig(config)
 	// check that members are all unique in the groups
 	memberUsage := make(map[string]string) // maps member to group it appears in

proxy/config_windows_test.go

@@ -38,5 +38,4 @@ func TestConfig_SanitizeCommand(t *testing.T) {
 	args, err = SanitizeCommand("")
 	assert.Error(t, err)
 	assert.Nil(t, args)
-
 }

proxy/process.go

@@ -8,6 +8,7 @@ import (
 	"net/http"
 	"net/url"
 	"os/exec"
+	"runtime"
 	"strconv"
 	"strings"
 	"sync"
@@ -400,8 +401,38 @@ func (p *Process) stopCommand(sigtermTTL time.Duration) {
 		return
 	}
 
-	if err := p.terminateProcess(); err != nil {
+	// if err := p.terminateProcess(); err != nil {
-		p.proxyLogger.Debugf("<%s> Process already terminated: %v (normal during shutdown)", p.ID, err)
+	// 	p.proxyLogger.Debugf("<%s> Process already terminated: %v (normal during shutdown)", p.ID, err)
+	// }
+	// the default cmdStop to taskkill /f /t /pid ${PID}
+	if runtime.GOOS == "windows" && strings.TrimSpace(p.config.CmdStop) == "" {
+		p.config.CmdStop = "taskkill /f /t /pid ${PID}"
+	}
+
+	if p.config.CmdStop != "" {
+		// replace ${PID} with the pid of the process
+		stopArgs, err := SanitizeCommand(strings.ReplaceAll(p.config.CmdStop, "${PID}", fmt.Sprintf("%d", p.cmd.Process.Pid)))
+		if err != nil {
+			p.proxyLogger.Errorf("<%s> Failed to sanitize stop command: %v", p.ID, err)
+			return
+		}
+
+		p.proxyLogger.Debugf("<%s> Executing stop command: %s", p.ID, strings.Join(stopArgs, " "))
+
+		stopCmd := exec.Command(stopArgs[0], stopArgs[1:]...)
+		stopCmd.Stdout = p.processLogger
+		stopCmd.Stderr = p.processLogger
+		stopCmd.Env = p.config.Env
+
+		if err := stopCmd.Run(); err != nil {
+			p.proxyLogger.Errorf("<%s> Failed to exec stop command: %v", p.ID, err)
+			return
+		}
+	} else {
+		if err := p.cmd.Process.Signal(syscall.SIGTERM); err != nil {
+			p.proxyLogger.Errorf("<%s> Failed to send SIGTERM to process: %v", p.ID, err)
+			return
+		}
 	}
 
 	select {

proxy/process_stop.go

@@ -1,9 +0,0 @@
-//go:build !windows
-
-package proxy
-
-import "syscall"
-
-func (p *Process) terminateProcess() error {
-	return p.cmd.Process.Signal(syscall.SIGTERM)
-}

proxy/process_stop_windows.go

@@ -1,14 +0,0 @@
-//go:build windows
-
-package proxy
-
-import (
-	"fmt"
-	"os/exec"
-)
-
-func (p *Process) terminateProcess() error {
-	pid := fmt.Sprintf("%d", p.cmd.Process.Pid)
-	cmd := exec.Command("taskkill", "/f", "/t", "/pid", pid)
-	return cmd.Run()
-}

proxy/process_test.go

@@ -449,3 +449,22 @@ func TestProcess_ForceStopWithKill(t *testing.T) {
 	// the request should have been interrupted by SIGKILL
 	<-waitChan
 }
+
+func TestProcess_StopCmd(t *testing.T) {
+	config := getTestSimpleResponderConfig("test_stop_cmd")
+
+	if runtime.GOOS == "windows" {
+		config.CmdStop = "taskkill /f /t /pid ${PID}"
+	} else {
+		config.CmdStop = "kill -TERM ${PID}"
+	}
+
+	process := NewProcess("testStopCmd", 2, config, debugLogger, debugLogger)
+	defer process.Stop()
+
+	err := process.start()
+	assert.Nil(t, err)
+	assert.Equal(t, process.CurrentState(), StateReady)
+	process.StopImmediately()
+	assert.Equal(t, process.CurrentState(), StateStopped)
+}