Allow setting of maxBuffer for packing external modules

lib/packExternalModules.js

@@ -94,13 +94,14 @@ module.exports = {
       this.serverless.cli.log('Packing external modules: ' + prodModules.join(", "));
 
       const tmpPackageJson = path.join(this.serverless.config.servicePath, 'package.json');
-    
+
       // create a temp package.json in dist directory so that we can install the dependencies later.
       fs.writeFileSync(tmpPackageJson, "{}");
 
       return new BbPromise((resolve, reject) => {
         npm.install(prodModules, {
           cwd: this.serverless.config.servicePath,
+          maxBuffer: this.serverless.service.custom.packExternalModulesMaxBuffer || 200 * 1024,
           save: true
         }).then(() => {
           // fs.unlink(tmpPackageJson);

package.json

@@ -33,7 +33,7 @@
     "fs-extra": "^0.26.7",
     "glob": "^7.1.2",
     "lodash": "^4.17.4",
-    "npm-programmatic": "0.0.5",
+    "npm-programmatic": "^0.0.7",
     "ts-node": "^3.2.0"
   },
   "devDependencies": {