Implement per instance command override on backend

pkg/backends/backend.go

@@ -142,27 +142,49 @@ func (o *Options) getBackend() backend {
 	}
 }
 
-func (o *Options) isDockerEnabled(backend *config.BackendSettings) bool {
-	if backend.Docker != nil && backend.Docker.Enabled && o.BackendType != BackendTypeMlxLm {
-		return true
+// isDockerEnabled checks if Docker is enabled with an optional override
+func (o *Options) isDockerEnabled(backend *config.BackendSettings, dockerEnabledOverride *bool) bool {
+	// Check if backend supports Docker
+	if backend.Docker == nil {
+		return false
 	}
-	return false
+
+	// MLX doesn't support Docker
+	if o.BackendType == BackendTypeMlxLm {
+		return false
+	}
+
+	// Check for instance-level override
+	if dockerEnabledOverride != nil {
+		return *dockerEnabledOverride
+	}
+
+	// Fall back to config value
+	return backend.Docker.Enabled
 }
 
 func (o *Options) IsDockerEnabled(backendConfig *config.BackendConfig) bool {
 	backendSettings := o.getBackendSettings(backendConfig)
-	return o.isDockerEnabled(backendSettings)
+	return o.isDockerEnabled(backendSettings, nil)
 }
 
 // GetCommand builds the command to run the backend
-func (o *Options) GetCommand(backendConfig *config.BackendConfig) string {
-
+func (o *Options) GetCommand(backendConfig *config.BackendConfig, dockerEnabled *bool, commandOverride string) string {
 	backendSettings := o.getBackendSettings(backendConfig)
 
-	if o.isDockerEnabled(backendSettings) {
+	// Determine if Docker is enabled
+	useDocker := o.isDockerEnabled(backendSettings, dockerEnabled)
+
+	if useDocker {
 		return "docker"
 	}
 
+	// Check for command override (only applies when not in Docker mode)
+	if commandOverride != "" {
+		return commandOverride
+	}
+
+	// Fall back to config command
 	return backendSettings.Command
 }
 
@@ -177,7 +199,7 @@ func (o *Options) BuildCommandArgs(backendConfig *config.BackendConfig) []string
 		return args
 	}
 
-	if o.isDockerEnabled(backendSettings) {
+	if o.isDockerEnabled(backendSettings, nil) {
 		// For Docker, start with Docker args
 		args = append(args, backendSettings.Docker.Args...)
 		args = append(args, backendSettings.Docker.Image)
@@ -202,7 +224,7 @@ func (o *Options) BuildEnvironment(backendConfig *config.BackendConfig, environm
 		maps.Copy(env, backendSettings.Environment)
 	}
 
-	if o.isDockerEnabled(backendSettings) {
+	if o.isDockerEnabled(backendSettings, nil) {
 		if backendSettings.Docker.Environment != nil {
 			maps.Copy(env, backendSettings.Docker.Environment)
 		}

pkg/backends/llama_test.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"llamactl/pkg/backends"
+	"llamactl/pkg/config"
 	"llamactl/pkg/testutil"
 	"reflect"
 	"testing"
@@ -549,3 +550,79 @@ func TestParseLlamaCommand_ExtraArgs(t *testing.T) {
 		})
 	}
 }
+func TestLlamaCppGetCommand_WithOverrides(t *testing.T) {
+	tests := []struct {
+		name            string
+		dockerInConfig  bool
+		dockerEnabled   *bool
+		commandOverride string
+		expected        string
+	}{
+		{
+			name:            "no overrides - use config command",
+			dockerInConfig:  false,
+			dockerEnabled:   nil,
+			commandOverride: "",
+			expected:        "/usr/bin/llama-server",
+		},
+		{
+			name:            "override to enable docker",
+			dockerInConfig:  false,
+			dockerEnabled:   boolPtr(true),
+			commandOverride: "",
+			expected:        "docker",
+		},
+		{
+			name:            "override to disable docker",
+			dockerInConfig:  true,
+			dockerEnabled:   boolPtr(false),
+			commandOverride: "",
+			expected:        "/usr/bin/llama-server",
+		},
+		{
+			name:            "command override",
+			dockerInConfig:  false,
+			dockerEnabled:   nil,
+			commandOverride: "/custom/llama-server",
+			expected:        "/custom/llama-server",
+		},
+		{
+			name:            "docker takes precedence over command override",
+			dockerInConfig:  false,
+			dockerEnabled:   boolPtr(true),
+			commandOverride: "/custom/llama-server",
+			expected:        "docker",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			backendConfig := &config.BackendConfig{
+				LlamaCpp: config.BackendSettings{
+					Command: "/usr/bin/llama-server",
+					Docker: &config.DockerSettings{
+						Enabled: tt.dockerInConfig,
+						Image:   "test-image",
+					},
+				},
+			}
+
+			opts := backends.Options{
+				BackendType: backends.BackendTypeLlamaCpp,
+				LlamaServerOptions: &backends.LlamaServerOptions{
+					Model: "test-model.gguf",
+				},
+			}
+
+			result := opts.GetCommand(backendConfig, tt.dockerEnabled, tt.commandOverride)
+			if result != tt.expected {
+				t.Errorf("GetCommand() = %v, want %v", result, tt.expected)
+			}
+		})
+	}
+}
+
+// Helper function to create bool pointer
+func boolPtr(b bool) *bool {
+	return &b
+}

pkg/backends/mlx_test.go

@@ -2,6 +2,7 @@ package backends_test
 
 import (
 	"llamactl/pkg/backends"
+	"llamactl/pkg/config"
 	"llamactl/pkg/testutil"
 	"testing"
 )
@@ -274,3 +275,57 @@ func TestParseMlxCommand_ExtraArgs(t *testing.T) {
 		})
 	}
 }
+func TestMlxGetCommand_NoDocker(t *testing.T) {
+	// MLX backend should never use Docker
+	backendConfig := &config.BackendConfig{
+		MLX: config.BackendSettings{
+			Command: "/usr/bin/mlx-server",
+			Docker: &config.DockerSettings{
+				Enabled: true, // Even if enabled in config
+				Image:   "test-image",
+			},
+		},
+	}
+
+	opts := backends.Options{
+		BackendType: backends.BackendTypeMlxLm,
+		MlxServerOptions: &backends.MlxServerOptions{
+			Model: "test-model",
+		},
+	}
+
+	tests := []struct {
+		name            string
+		dockerEnabled   *bool
+		commandOverride string
+		expected        string
+	}{
+		{
+			name:            "ignores docker in config",
+			dockerEnabled:   nil,
+			commandOverride: "",
+			expected:        "/usr/bin/mlx-server",
+		},
+		{
+			name:            "ignores docker override",
+			dockerEnabled:   boolPtr(true),
+			commandOverride: "",
+			expected:        "/usr/bin/mlx-server",
+		},
+		{
+			name:            "respects command override",
+			dockerEnabled:   nil,
+			commandOverride: "/custom/mlx-server",
+			expected:        "/custom/mlx-server",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := opts.GetCommand(backendConfig, tt.dockerEnabled, tt.commandOverride)
+			if result != tt.expected {
+				t.Errorf("GetCommand() = %v, want %v", result, tt.expected)
+			}
+		})
+	}
+}

pkg/instance/instance.go

@@ -255,7 +255,7 @@ func (i *Instance) getCommand() string {
 		return ""
 	}
 
-	return opts.BackendOptions.GetCommand(i.globalBackendSettings)
+	return opts.BackendOptions.GetCommand(i.globalBackendSettings, opts.DockerEnabled, opts.CommandOverride)
 }
 
 func (i *Instance) buildCommandArgs() []string {

pkg/instance/options.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"llamactl/pkg/backends"
 	"llamactl/pkg/config"
+	"llamactl/pkg/validation"
 	"log"
 	"slices"
 	"sync"
@@ -22,6 +23,11 @@ type Options struct {
 	IdleTimeout *int `json:"idle_timeout,omitempty"` // minutes
 	// Environment variables
 	Environment map[string]string `json:"environment,omitempty"`
+
+	// Execution context overrides
+	DockerEnabled   *bool  `json:"docker_enabled,omitempty"`
+	CommandOverride string `json:"command_override,omitempty"`
+
 	// Assigned nodes
 	Nodes map[string]struct{} `json:"-"`
 	// Backend options
@@ -200,6 +206,28 @@ func (c *Options) validateAndApplyDefaults(name string, globalSettings *config.I
 		*c.IdleTimeout = 0
 	}
 
+	// Validate docker_enabled and command_override relationship
+	if c.DockerEnabled != nil && *c.DockerEnabled && c.CommandOverride != "" {
+		log.Printf("Instance %s: command_override cannot be set when docker_enabled is true, ignoring command_override", name)
+		c.CommandOverride = "" // Clear invalid configuration
+	}
+
+	// Validate command_override if set
+	if c.CommandOverride != "" {
+		if err := validation.ValidateStringForInjection(c.CommandOverride); err != nil {
+			log.Printf("Instance %s: invalid command_override: %v, clearing value", name, err)
+			c.CommandOverride = "" // Clear invalid value
+		}
+	}
+
+	// Validate docker_enabled for MLX backend
+	if c.BackendOptions.BackendType == backends.BackendTypeMlxLm {
+		if c.DockerEnabled != nil && *c.DockerEnabled {
+			log.Printf("Instance %s: docker_enabled is not supported for MLX backend, ignoring", name)
+			c.DockerEnabled = nil // Clear invalid configuration
+		}
+	}
+
 	// Apply defaults from global settings for nil fields
 	if globalSettings != nil {
 		if c.AutoRestart == nil {