feat: Make config file path configurable (#85)

Author: ivov

docs/development.md

@@ -13,6 +13,12 @@ touch config.json && echo '<json-config-content>' > config.json
 sudo mv config.json /etc/n8n-task-runners.json
 ```
 
+Alternatively, use this environment variable to specify the config file path:
+
+```sh
+export N8N_RUNNERS_CONFIG_PATH=/path/to/your/config.json
+```
+
 3. Make your changes.
 
 4. Build launcher:

docs/setup.md

@@ -44,49 +44,10 @@ sequenceDiagram
 
 ## Config file
 
-Example config file at `/etc/n8n-task-runners.json`:
-
-```json
-{
-  "task-runners": [
-    {
-      "runner-type": "javascript",
-      "workdir": "/usr/local/bin",
-      "command": "/usr/local/bin/node",
-      "args": [
-        "--disallow-code-generation-from-strings",
-        "--disable-proto=delete",
-        "/usr/local/lib/node_modules/n8n/node_modules/@n8n/task-runner/dist/start.js"
-      ],
-      "health-check-server-port": "5681",
-      "allowed-env": ["PATH", "GENERIC_TIMEZONE"],
-      "env-overrides": {
-        "N8N_RUNNERS_TASK_TIMEOUT": "80",
-        "N8N_RUNNERS_AUTO_SHUTDOWN_TIMEOUT": "120",
-        "N8N_RUNNERS_MAX_CONCURRENCY": "3",
-        "NODE_FUNCTION_ALLOW_BUILTIN": "crypto",
-        "NODE_FUNCTION_ALLOW_EXTERNAL": "moment",
-        "NODE_OPTIONS": "--max-old-space-size=4096"
-      }
-    },
-    {
-      "runner-type": "python",
-      "workdir": "/usr/local/bin",
-      "command": "/usr/local/bin/python",
-      "args": [
-        "/usr/local/lib/python3.13/site-packages/n8n/task-runner-python/main.py"
-      ],
-      "health-check-server-port": "5682", 
-      "allowed-env": ["PATH", "GENERIC_TIMEZONE"],
-      "env-overrides": {
-        "N8N_RUNNERS_TASK_TIMEOUT": "30",
-        "N8N_RUNNERS_AUTO_SHUTDOWN_TIMEOUT": "30",
-        "N8N_RUNNERS_MAX_CONCURRENCY": "2"
-      }
-    }
-  ]
-}
-```
+The launcher reads its config file from `/etc/n8n-task-runners.json` by default, or from the file path specified by the `N8N_RUNNERS_CONFIG_PATH` environment variable.
+
+For an example, refer to the [config file](https://github.com/n8n-io/n8n/blob/master/docker/images/runners/n8n-task-runners.json) used in the [`n8nio/runners`](https://hub.docker.com/r/n8nio/runners) Docker image.
+
 
 | Property       | Description                                                                                                             |
 | --------------- | ----------------------------------------------------------------------------------------------------------------------- |
@@ -95,8 +56,8 @@ Example config file at `/etc/n8n-task-runners.json`:
 | `command`       | Command to start the task runner.                                                                                       |
 | `args`          | Args and flags to use with `command`.                                                                                           |
 | `health-check-server-port` | Port for the runner's health check server. When a single runner is configured, this is optional and defaults to `5681`. When multiple runners are configured, this is required and must be unique per runner.
-| `allowed-env`   | Env vars that the launcher will pass through from its own environment to the runner. See [environment](environment.md). |
-| `env-overrides` | Env vars that the launcher will set directly on the runner. See [environment](environment.md).                          |
+| `allowed-env`   | Env vars that the launcher will pass through from its own environment to the runner. See [environment variables](#environment-variables).
+| `env-overrides` | Env vars that the launcher will set directly on the runner. See [environment variables](#environment-variables).
 
 ## Environment variables
 

internal/config/config.go

@@ -13,8 +13,6 @@ import (
 	"github.com/sethvargo/go-envconfig"
 )
 
-var configPath = "/etc/n8n-task-runners.json"
-
 const (
 	// EnvVarHealthCheckPort is the env var for the port for the launcher's health check server.
 	EnvVarHealthCheckPort = "N8N_RUNNERS_LAUNCHER_HEALTH_CHECK_PORT"
@@ -52,6 +50,9 @@ type BaseConfig struct {
 	// RunnerHealthCheckServerHost is the host for all runners' health check servers.
 	RunnerHealthCheckServerHost string `env:"N8N_RUNNERS_HEALTH_CHECK_SERVER_HOST, default=127.0.0.1"`
 
+	// ConfigPath is the path to the runners config file. Default: `/etc/n8n-task-runners.json`.
+	ConfigPath string `env:"N8N_RUNNERS_CONFIG_PATH, default=/etc/n8n-task-runners.json"`
+
 	// Sentry is the Sentry config for the launcher, a subset of what is defined in:
 	// https://docs.sentry.io/platforms/go/configuration/options/
 	Sentry *SentryConfig
@@ -92,7 +93,7 @@ type RunnerConfig struct {
 }
 
 // LoadLauncherConfig loads the launcher's base config from the launcher's environment and
-// loads runner configs from the config file at `/etc/n8n-task-runners.json`.
+// loads runner configs from the config file specified by N8N_RUNNERS_CONFIG_PATH.
 func LoadLauncherConfig(runnerTypes []string, lookuper envconfig.Lookuper) (*LauncherConfig, error) {
 	ctx := context.Background()
 
@@ -131,7 +132,7 @@ func LoadLauncherConfig(runnerTypes []string, lookuper envconfig.Lookuper) (*Lau
 
 	// runners
 
-	runnerConfigs, err := readLauncherConfigFile(runnerTypes)
+	runnerConfigs, err := readLauncherConfigFile(baseConfig.ConfigPath, runnerTypes)
 	if err != nil {
 		cfgErrs = append(cfgErrs, err)
 	}
@@ -146,9 +147,10 @@ func LoadLauncherConfig(runnerTypes []string, lookuper envconfig.Lookuper) (*Lau
 	}, nil
 }
 
-// readLauncherConfigFile reads the config file at `/etc/n8n-task-runners.json` and
+// readLauncherConfigFile reads the config file at the specified path and
 // returns the runner config(s) for the requested runner type(s).
-func readLauncherConfigFile(runnerTypes []string) (map[string]*RunnerConfig, error) {
+func readLauncherConfigFile(configPath string, runnerTypes []string) (map[string]*RunnerConfig, error) {
+	// #nosec G304 -- configPath is controlled by system administrator via environment variable
 	data, err := os.ReadFile(configPath)
 	if err != nil {
 		return nil, fmt.Errorf("failed to open config file at %s: %v", configPath, err)
@@ -164,7 +166,7 @@ func readLauncherConfigFile(runnerTypes []string) (map[string]*RunnerConfig, err
 	taskRunnersNum := len(fileConfig.TaskRunners)
 
 	if taskRunnersNum == 0 {
-		return nil, errs.ErrMissingRunnerConfig
+		return nil, fmt.Errorf("config file at %s contains no task runners", configPath)
 	}
 
 	runnerConfigs := make(map[string]*RunnerConfig)

internal/config/config_test.go

@@ -37,6 +37,7 @@ func TestLoadConfig(t *testing.T) {
 			envVars: map[string]string{
 				"N8N_RUNNERS_AUTH_TOKEN":      "test-token",
 				"N8N_RUNNERS_TASK_BROKER_URI": "http://localhost:5679",
+				"N8N_RUNNERS_CONFIG_PATH":     testConfigPath,
 				"SENTRY_DSN":                  "https://[email protected]/123",
 			},
 			runnerType:    "javascript",
@@ -48,6 +49,7 @@ func TestLoadConfig(t *testing.T) {
 			envVars: map[string]string{
 				"N8N_RUNNERS_AUTH_TOKEN":      "test-token",
 				"N8N_RUNNERS_TASK_BROKER_URI": "http://127.0.0.1:5679",
+				"N8N_RUNNERS_CONFIG_PATH":     testConfigPath,
 				"SENTRY_DSN":                  "https://[email protected]/123",
 			},
 			runnerType:    "javascript",
@@ -57,9 +59,7 @@ func TestLoadConfig(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			configPath = testConfigPath
-
-			err := os.WriteFile(configPath, []byte(tt.configContent), 0600)
+			err := os.WriteFile(testConfigPath, []byte(tt.configContent), 0600)
 			require.NoError(t, err, "Failed to write test config file")
 
 			lookuper := envconfig.MapLookuper(tt.envVars)
@@ -93,17 +93,19 @@ func TestConfigFileErrors(t *testing.T) {
 			envVars: map[string]string{
 				"N8N_RUNNERS_AUTH_TOKEN":      "test-token",
 				"N8N_RUNNERS_TASK_BROKER_URI": "http://localhost:5679",
+				"N8N_RUNNERS_CONFIG_PATH":     testConfigPath,
 			},
 		},
 		{
 			name: "empty task runners array",
 			configContent: `{
 				"task-runners": []
 			}`,
-			expectedError: "found no task runner configs",
+			expectedError: "contains no task runners",
 			envVars: map[string]string{
 				"N8N_RUNNERS_AUTH_TOKEN":      "test-token",
 				"N8N_RUNNERS_TASK_BROKER_URI": "http://localhost:5679",
+				"N8N_RUNNERS_CONFIG_PATH":     testConfigPath,
 			},
 		},
 		{
@@ -121,16 +123,15 @@ func TestConfigFileErrors(t *testing.T) {
 			envVars: map[string]string{
 				"N8N_RUNNERS_AUTH_TOKEN":      "test-token",
 				"N8N_RUNNERS_TASK_BROKER_URI": "http://localhost:5679",
+				"N8N_RUNNERS_CONFIG_PATH":     testConfigPath,
 			},
 		},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			configPath = testConfigPath
-
 			if tt.configContent != "" {
-				err := os.WriteFile(configPath, []byte(tt.configContent), 0600)
+				err := os.WriteFile(testConfigPath, []byte(tt.configContent), 0600)
 				require.NoError(t, err, "Failed to write test config file")
 			}
 
@@ -250,11 +251,11 @@ func TestBackwardsCompatibilityPortDefaults(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			configPath = filepath.Join(t.TempDir(), "test-config.json")
-			err := os.WriteFile(configPath, []byte(tt.configContent), 0600)
+			testConfigPath := filepath.Join(t.TempDir(), "test-config.json")
+			err := os.WriteFile(testConfigPath, []byte(tt.configContent), 0600)
 			require.NoError(t, err)
 
-			configs, err := readLauncherConfigFile(tt.runnerTypes)
+			configs, err := readLauncherConfigFile(testConfigPath, tt.runnerTypes)
 
 			if tt.expectError {
 				assert.Error(t, err)

internal/errs/errs.go

@@ -14,7 +14,4 @@ var (
 
 	// ErrNegativeAutoShutdownTimeout is returned when the auto shutdown timeout is a negative integer.
 	ErrNegativeAutoShutdownTimeout = errors.New("negative auto-shutdown timeout - N8N_RUNNERS_AUTO_SHUTDOWN_TIMEOUT must be >= 0")
-
-	// ErrMissingRunnerConfig is returned when the config file does not contain any runner configs.
-	ErrMissingRunnerConfig = errors.New("found no task runner configs at /etc/n8n-task-runners.json")
 )