feat: read package.json config values

Also will read config environment variables in the same format
that npm@11 will set them when read from the package.json

Fixes #3156

Author: lukekarrys

README.md

@@ -235,25 +235,44 @@ Some additional resources for Node.js native addons and writing `gyp` configurat
 
 ## Configuration
 
+### package.json
+
+Use the `config` object in your package.json with each key in the form `node_gyp_OPTION_NAME`. Any of the command
+options listed above can be set (dashes in option names should be replaced by underscores).
+
+For example, to set `devdir` equal to `/tmp/.gyp`, your package.json would contain this:
+
+```json
+{
+  "config": {
+    "node_gyp_devdir": "/tmp/.gyp"
+  }
+}
+```
+
 ### Environment variables
 
-Use the form `npm_config_OPTION_NAME` for any of the command options listed
+Use the form `npm_package_config_node_gyp_OPTION_NAME` for any of the command options listed
 above (dashes in option names should be replaced by underscores).
 
 For example, to set `devdir` equal to `/tmp/.gyp`, you would:
 
 Run this on Unix:
 
 ```bash
-export npm_config_devdir=/tmp/.gyp
+export npm_package_config_node_gyp_devdir=/tmp/.gyp
 ```
 
 Or this on Windows:
 
 ```console
-set npm_config_devdir=c:\temp\.gyp
+set npm_package_config_node_gyp_devdir=c:\temp\.gyp
 ```
 
+Note that in versions of npm before v11 it was possible to use the prefix `npm_config_` for
+environement variables. This was deprecated in npm@11 and will be removed in npm@12 so it
+is recommened to convert your environment variables to the above format.
+
 ### `npm` configuration for npm versions before v9
 
 Use the form `OPTION_NAME` for any of the command options listed above.

lib/node-gyp.js

@@ -145,6 +145,29 @@ class Gyp extends EventEmitter {
       }
     })
 
+    // Read values that npm sets based on the `config` object in package.json.
+    // These take precendence over the npm_config_ prefixed values which
+    // are deprecated in npm@11.
+    // These can also be set directly in the environment, if setting in
+    // package.json is not desired.
+    const npmPackageConfigPrefix = 'npm_package_config_node_gyp_'
+    Object.keys(process.env).forEach((name) => {
+      if (name.indexOf(npmPackageConfigPrefix) !== 0) {
+        return
+      }
+      const val = process.env[name]
+      name = name.substring(npmPackageConfigPrefix.length)
+      // gyp@741b7f1 enters an infinite loop when it encounters
+      // zero-length options so ensure those don't get through.
+      if (name) {
+        // convert names like force_process_config to force-process-config
+        if (name.includes('_')) {
+          name = name.replace(/_/g, '-')
+        }
+        this.opts[name] = val
+      }
+    })
+
     if (this.opts.loglevel) {
       log.logger.level = this.opts.loglevel
     }