computeNodeJsVersion.js

computeNodeJsVersion.js

var path = require('path')
        , fs = require('fs');

var existsSync = fs.existsSync || path.existsSync;
var nodejsDir = path.resolve(process.env['programfiles(x86)'] || process.env['programfiles'], 'nodejs');

if (!existsSync(nodejsDir))
	throw new Error('Unable to locate node.js installation directory at ' + nodejsDir);

var wwwroot = process.argv[2];
if (!existsSync(wwwroot))
	throw new Error('Usage: node.exe computeNodeJsVersion.js <path_to_wwwroot>');

var packageJson = path.resolve(wwwroot, 'package.json');
if (!existsSync(packageJson)) {
	console.log('The packge.json not found at ' + packageJson +'. No modifications performed.');
	process.exit(0); 
}

var json = JSON.parse(fs.readFileSync(packageJson, 'utf8'));
if (typeof json !== 'object' || typeof json.engines !== 'object' || typeof json.engines.node !== 'string') {
	console.log('The package.json at ' + packageJson 
		+ ' does not specify node.js engine constraints. No modifications performed.');
	process.exit(0);
}

var iisnodeYml = path.resolve(wwwroot, 'iisnode.yml');
var yml = '';
if (existsSync(iisnodeYml)) {
	yml = fs.readFileSync(iisnodeYml, 'utf8');
	if (yml.match(/^ *nodeProcessCommandLine *:/m)) {
		console.log('The iisnode.yml at ' + iisnodeYml 
			+ ' explicitly sets nodeProcessCommandLine. No modifications performed.');
		process.exit(0);
	}
}

// determine node.js versions available on the plarform

var versions = [];
fs.readdirSync(nodejsDir).forEach(function (dir) {
	if (dir.match(/^\d+\.\d+\.\d+$/) && existsSync(path.resolve(nodejsDir, dir, 'node.exe')))
		versions.push(dir);
});

// calculate actual node.js version to use for the application

var version = require('semver').maxSatisfying(versions, json.engines.node);
if (!version) {
	console.log('None of the avilable node.js versions ' + JSON.stringify(versions)
		+ ' matches the application\'s node.js version constraint ' + json.engines.node);
	process.exit(-1);
}
else {
	console.log('Selected node.js version ' + version +'.');
}

// save the version information to iisnode.yml

if (yml !== '')
	yml += '\r\n';

yml += 'nodeProcessCommandLine: "' + path.resolve(nodejsDir, version, 'node.exe') + '" "' + path.resolve(nodejsDir, 'interceptor.js') + '"';
fs.writeFileSync(iisnodeYml, yml);