src: set default config as node.config.json

Author: marco-ippolito

Makefile

@@ -807,7 +807,7 @@ doc: $(NODE_EXE) doc-only ## Build Node.js, and then build the documentation wit
 
 out/doc:
 	mkdir -p $@
-	cp doc/node_config_json_schema.json $@
+	cp doc/node-config-schema.json $@
 
 # If it's a source tarball, doc/api already contains the generated docs.
 # Just copy everything under doc/api over.

doc/api/cli.md

@@ -939,29 +939,30 @@ files with no extension will be treated as WebAssembly if they begin with the
 WebAssembly magic number (`\0asm`); otherwise they will be treated as ES module
 JavaScript.
 
-### `--experimental-config-file`
+### `--experimental-config-file=config`
 
 <!-- YAML
 added: REPLACEME
 -->
 
 > Stability: 1.0 - Early development
 
-Use this flag to specify a configuration file that will be loaded and parsed
-before the application starts.
+If present, Node.js will look for a
+configuration file at the specified path.
 Node.js will read the configuration file and apply the settings.
 The configuration file should be a JSON file
 with the following structure:
 
+> \[!NOTE]
+> Replace `vX.Y.Z` in the `$schema` with the version of Node.js you are using.
+
 ```json
 {
-  "$schema": "https://nodejs.org/dist/REPLACEME/docs/node_config_json_schema.json",
+  "$schema": "https://nodejs.org/dist/vX.Y.Z/docs/node-config-schema.json",
   "nodeOptions": {
-    "experimental-transform-types": true,
     "import": [
-      "amaro/transform"
+      "amaro/strip"
     ],
-    "disable-warning": "ExperimentalWarning",
     "watch-path": "src",
     "watch-preserve-output": true
   }
@@ -972,7 +973,7 @@ In the `nodeOptions` field, only flags that are allowed in [`NODE_OPTIONS`][] ar
 No-op flags are not supported.
 Not all V8 flags are currently supported.
 
-It is possible to use the [official JSON schema](../node_config_json_schema.json)
+It is possible to use the [official JSON schema](../node-config-schema.json)
 to validate the configuration file, which may vary depending on the Node.js version.
 Each key in the configuration file corresponds to a flag that can be passed
 as a command-line argument. The value of the key is the value that would be
@@ -982,7 +983,7 @@ For example, the configuration file above is equivalent to
 the following command-line arguments:
 
 ```bash
-node --experimental-transform-types --import amaro/transform --disable-warning=ExperimentalWarning --watch-path=src --watch-preserve-output
+node --import amaro/strip --watch-path=src --watch-preserve-output
 ```
 
 The priority in configuration is as follows:
@@ -1004,6 +1005,18 @@ unknown keys or keys that cannot used in `NODE_OPTIONS`.
 Node.js will not sanitize or perform validation on the user-provided configuration,
 so **NEVER** use untrusted configuration files.
 
+### `--experimental-default-config-file`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1.0 - Early development
+
+If the `--experimental-default-config-file` flag is present, Node.js will look for a
+`node.config.json` file in the current working directory and load it as a
+as configuration file.
+
 ### `--experimental-eventsource`
 
 <!-- YAML

doc/node_config_json_schema.json renamed to doc/node-config-schema.json

@@ -169,7 +169,10 @@ Interpret as either ES modules or CommonJS modules input via --eval or STDIN, wh
 .js or extensionless files whose nearest parent package.json lacks a "type" field, unless under node_modules.
 .
 .It Fl -experimental-config-file
-Enable support for experimental config file
+Specifies the configuration file to load.
+.
+.It Fl -experimental-default-config-file
+Enable support for automatically loading node.config.json.
 .
 .It Fl -experimental-import-meta-resolve
 Enable experimental ES modules support for import.meta.resolve().

doc/node.1

@@ -393,7 +393,8 @@ function setupSQLite() {
 }
 
 function initializeConfigFileSupport() {
-  if (getOptionValue('--experimental-config-file')) {
+  if (getOptionValue('--experimental-default-config-file') ||
+      getOptionValue('--experimental-config-file')) {
     emitExperimentalWarning('--experimental-config-file');
   }
 }

lib/internal/process/pre_execution.js

@@ -8,22 +8,32 @@ namespace node {
 
 std::optional<std::string_view> ConfigReader::GetDataFromArgs(
     const std::vector<std::string>& args) {
-  constexpr std::string_view flag = "--experimental-config-file";
+  constexpr std::string_view flag_path = "--experimental-config-file";
+  constexpr std::string_view default_file =
+      "--experimental-default-config-file";
+
+  bool has_default_config_file = false;
 
   for (auto it = args.begin(); it != args.end(); ++it) {
-    if (*it == flag) {
+    if (*it == flag_path) {
       // Case: "--experimental-config-file foo"
       if (auto next = std::next(it); next != args.end()) {
         return *next;
       }
-    } else if (it->starts_with(flag)) {
+    } else if (it->starts_with(flag_path)) {
       // Case: "--experimental-config-file=foo"
-      if (it->size() > flag.size() && (*it)[flag.size()] == '=') {
-        return it->substr(flag.size() + 1);
+      if (it->size() > flag_path.size() && (*it)[flag_path.size()] == '=') {
+        return it->substr(flag_path.size() + 1);
       }
+    } else if (*it == default_file || it->starts_with(default_file)) {
+      has_default_config_file = true;
     }
   }
 
+  if (has_default_config_file) {
+    return "node.config.json";
+  }
+
   return std::nullopt;
 }
 

src/node_config_file.cc

@@ -690,7 +690,10 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
   Implies("--env-file-if-exists", "[has_env_file_string]");
   AddOption("--experimental-config-file",
             "set config file from supplied file",
-            &EnvironmentOptions::experimental_config_file);
+            &EnvironmentOptions::experimental_config_file_path);
+  AddOption("--experimental-default-config-file",
+            "set config file from default config file",
+            &EnvironmentOptions::experimental_default_config_file);
   AddOption("--test",
             "launch test runner on startup",
             &EnvironmentOptions::test_runner);

src/node_options.cc

@@ -257,7 +257,8 @@ class EnvironmentOptions : public Options {
 
   bool report_exclude_env = false;
   bool report_exclude_network = false;
-  std::string experimental_config_file;
+  std::string experimental_config_file_path;
+  bool experimental_default_config_file = false;
 
   inline DebugOptions* get_debug_options() { return &debug_options_; }
   inline const DebugOptions& debug_options() const { return debug_options_; }

src/node_options.h

@@ -0,0 +1,5 @@
+{
+  "nodeOptions": {
+    "max-http-header-size": 10
+  }
+}

test/fixtures/rc/default/node.config.json

@@ -0,0 +1,5 @@
+{
+  "nodeOptions": {
+    "max-http-header-size": 20
+  }
+}