Node version check w/o semver (#7097)

closes #6691

- removes dependency on semver & package.json in preinstall script
- has a simplified proxy of semver to look for the right version numbers

core/server/utils/npm/preinstall.js

@@ -0,0 +1,47 @@
+var validVersions = process.env.npm_package_engines_node.split(' || '),
+    currentVersion = process.versions.node,
+    foundMatch = false,
+    majMinRegex = /(\d+\.\d+)/,
+    majorRegex = /^\d+/,
+    minorRegex = /\d+$/,
+    exitCodes = {
+        NODE_VERSION_UNSUPPORTED: 231
+    };
+
+function doError() {
+    console.error('\x1B[31mERROR: Unsupported version of Node');
+    console.error('\x1B[37mGhost supports LTS Node versions: ' + process.env.npm_package_engines_node);
+    console.error('You are currently using version: ' + process.versions.node + '\033[0m');
+    console.error('\x1B[32mThis check can be overridden, see http://support.ghost.org/supported-node-versions/ for more info\033[0m');
+
+    process.exit(exitCodes.NODE_VERSION_UNSUPPORTED);
+}
+
+if (process.env.GHOST_NODE_VERSION_CHECK === 'false') {
+    console.log('\x1B[33mSkipping Node version check\033[0m');
+} else {
+    try {
+        currentVersion = currentVersion.match(majMinRegex)[0];
+
+        validVersions.forEach(function (version) {
+            var matchChar = version.charAt(0),
+                versionString = version.match(majMinRegex)[0];
+
+            if (
+                (matchChar === '~' && currentVersion === versionString)
+                || (matchChar === '^'
+                    && currentVersion.match(majorRegex)[0] === versionString.match(majorRegex)[0]
+                    && currentVersion.match(minorRegex)[0] >= versionString.match(minorRegex)[0]
+                )
+            ) {
+                foundMatch = true;
+            }
+        });
+
+        if (foundMatch !== true) {
+            doError();
+        }
+    } catch (e) {
+        doError();
+    }
+}

package.json

@@ -18,7 +18,7 @@
   "license": "MIT",
   "main": "./core/index",
   "scripts": {
-    "preinstall": "npm install semver && node -e \"require('./core/server/utils/startup-check.js').nodeVersion()\"",
+    "preinstall": "node core/server/utils/npm/preinstall.js",
     "start": "node index",
     "test": "grunt validate --verbose"
   },