add TOKEN_FILE env var

beszel/internal/agent/client.go

@@ -10,6 +10,7 @@ import (
 	"net"
 	"net/http"
 	"net/url"
+	"os"
 	"path"
 	"strings"
 	"time"
@@ -53,9 +54,9 @@ func newWebSocketClient(agent *Agent) (client *WebSocketClient, err error) {
 		return nil, errors.New("invalid hub URL")
 	}
 	// get registration token
-	client.token, _ = GetEnv("TOKEN")
-	if client.token == "" {
-		return nil, errors.New("TOKEN environment variable not set")
+	client.token, err = getToken()
+	if err != nil {
+		return nil, err
 	}
 
 	client.agent = agent
@@ -65,6 +66,27 @@ func newWebSocketClient(agent *Agent) (client *WebSocketClient, err error) {
 	return client, nil
 }
 
+// getToken returns the token for the WebSocket client.
+// It first checks the TOKEN environment variable, then the TOKEN_FILE environment variable.
+// If neither is set, it returns an error.
+func getToken() (string, error) {
+	// get token from env var
+	token, _ := GetEnv("TOKEN")
+	if token != "" {
+		return token, nil
+	}
+	// get token from file
+	tokenFile, _ := GetEnv("TOKEN_FILE")
+	if tokenFile == "" {
+		return "", errors.New("must set TOKEN or TOKEN_FILE")
+	}
+	tokenBytes, err := os.ReadFile(tokenFile)
+	if err != nil {
+		return "", err
+	}
+	return string(tokenBytes), nil
+}
+
 // getOptions returns the WebSocket client options, creating them if necessary.
 // It configures the connection URL, TLS settings, and authentication headers.
 func (client *WebSocketClient) getOptions() *gws.ClientOption {

beszel/internal/agent/client_test.go

@@ -61,7 +61,7 @@ func TestNewWebSocketClient(t *testing.T) {
 			hubURL:      "http://localhost:8080",
 			token:       "",
 			expectError: true,
-			errorMsg:    "TOKEN environment variable not set",
+			errorMsg:    "must set TOKEN or TOKEN_FILE",
 		},
 	}
 
@@ -389,3 +389,150 @@ func TestWebSocketClient_ConnectRateLimit(t *testing.T) {
 	err = client.Connect()
 	assert.Error(t, err, "Connection should fail but not hang")
 }
+
+// TestGetToken tests the getToken function with various scenarios
+func TestGetToken(t *testing.T) {
+	unsetEnvVars := func() {
+		os.Unsetenv("BESZEL_AGENT_TOKEN")
+		os.Unsetenv("TOKEN")
+		os.Unsetenv("BESZEL_AGENT_TOKEN_FILE")
+		os.Unsetenv("TOKEN_FILE")
+	}
+
+	t.Run("token from TOKEN environment variable", func(t *testing.T) {
+		unsetEnvVars()
+
+		// Set TOKEN env var
+		expectedToken := "test-token-from-env"
+		os.Setenv("TOKEN", expectedToken)
+		defer os.Unsetenv("TOKEN")
+
+		token, err := getToken()
+		assert.NoError(t, err)
+		assert.Equal(t, expectedToken, token)
+	})
+
+	t.Run("token from BESZEL_AGENT_TOKEN environment variable", func(t *testing.T) {
+		unsetEnvVars()
+
+		// Set BESZEL_AGENT_TOKEN env var (should take precedence)
+		expectedToken := "test-token-from-beszel-env"
+		os.Setenv("BESZEL_AGENT_TOKEN", expectedToken)
+		defer os.Unsetenv("BESZEL_AGENT_TOKEN")
+
+		token, err := getToken()
+		assert.NoError(t, err)
+		assert.Equal(t, expectedToken, token)
+	})
+
+	t.Run("token from TOKEN_FILE", func(t *testing.T) {
+		unsetEnvVars()
+
+		// Create a temporary token file
+		expectedToken := "test-token-from-file"
+		tokenFile, err := os.CreateTemp("", "token-test-*.txt")
+		require.NoError(t, err)
+		defer os.Remove(tokenFile.Name())
+
+		_, err = tokenFile.WriteString(expectedToken)
+		require.NoError(t, err)
+		tokenFile.Close()
+
+		// Set TOKEN_FILE env var
+		os.Setenv("TOKEN_FILE", tokenFile.Name())
+		defer os.Unsetenv("TOKEN_FILE")
+
+		token, err := getToken()
+		assert.NoError(t, err)
+		assert.Equal(t, expectedToken, token)
+	})
+
+	t.Run("token from BESZEL_AGENT_TOKEN_FILE", func(t *testing.T) {
+		unsetEnvVars()
+
+		// Create a temporary token file
+		expectedToken := "test-token-from-beszel-file"
+		tokenFile, err := os.CreateTemp("", "token-test-*.txt")
+		require.NoError(t, err)
+		defer os.Remove(tokenFile.Name())
+
+		_, err = tokenFile.WriteString(expectedToken)
+		require.NoError(t, err)
+		tokenFile.Close()
+
+		// Set BESZEL_AGENT_TOKEN_FILE env var (should take precedence)
+		os.Setenv("BESZEL_AGENT_TOKEN_FILE", tokenFile.Name())
+		defer os.Unsetenv("BESZEL_AGENT_TOKEN_FILE")
+
+		token, err := getToken()
+		assert.NoError(t, err)
+		assert.Equal(t, expectedToken, token)
+	})
+
+	t.Run("TOKEN takes precedence over TOKEN_FILE", func(t *testing.T) {
+		unsetEnvVars()
+
+		// Create a temporary token file
+		fileToken := "token-from-file"
+		tokenFile, err := os.CreateTemp("", "token-test-*.txt")
+		require.NoError(t, err)
+		defer os.Remove(tokenFile.Name())
+
+		_, err = tokenFile.WriteString(fileToken)
+		require.NoError(t, err)
+		tokenFile.Close()
+
+		// Set both TOKEN and TOKEN_FILE
+		envToken := "token-from-env"
+		os.Setenv("TOKEN", envToken)
+		os.Setenv("TOKEN_FILE", tokenFile.Name())
+		defer func() {
+			os.Unsetenv("TOKEN")
+			os.Unsetenv("TOKEN_FILE")
+		}()
+
+		token, err := getToken()
+		assert.NoError(t, err)
+		assert.Equal(t, envToken, token, "TOKEN should take precedence over TOKEN_FILE")
+	})
+
+	t.Run("error when neither TOKEN nor TOKEN_FILE is set", func(t *testing.T) {
+		unsetEnvVars()
+
+		token, err := getToken()
+		assert.Error(t, err)
+		assert.Equal(t, "", token)
+		assert.Contains(t, err.Error(), "must set TOKEN or TOKEN_FILE")
+	})
+
+	t.Run("error when TOKEN_FILE points to non-existent file", func(t *testing.T) {
+		unsetEnvVars()
+
+		// Set TOKEN_FILE to a non-existent file
+		os.Setenv("TOKEN_FILE", "/non/existent/file.txt")
+		defer os.Unsetenv("TOKEN_FILE")
+
+		token, err := getToken()
+		assert.Error(t, err)
+		assert.Equal(t, "", token)
+		assert.Contains(t, err.Error(), "no such file or directory")
+	})
+
+	t.Run("handles empty token file", func(t *testing.T) {
+		unsetEnvVars()
+
+		// Create an empty token file
+		tokenFile, err := os.CreateTemp("", "token-test-*.txt")
+		require.NoError(t, err)
+		defer os.Remove(tokenFile.Name())
+		tokenFile.Close()
+
+		// Set TOKEN_FILE env var
+		os.Setenv("TOKEN_FILE", tokenFile.Name())
+		defer os.Unsetenv("TOKEN_FILE")
+
+		token, err := getToken()
+		assert.NoError(t, err)
+		assert.Equal(t, "", token, "Empty file should return empty string")
+	})
+}