Re-use registry HTTP agent for package info requests

server/utils/fetchNpmPackage.js

@@ -0,0 +1,35 @@
+const url = require("url");
+const https = require("https");
+const gunzip = require("gunzip-maybe");
+const tar = require("tar-stream");
+
+const agent = require("./registryAgent");
+
+function fetchNpmPackage(packageConfig) {
+  return new Promise((resolve, reject) => {
+    const tarballURL = packageConfig.dist.tarball;
+
+    console.log(
+      `info: Fetching package for ${packageConfig.name} from ${tarballURL}`
+    );
+
+    const { hostname, pathname } = url.parse(tarballURL);
+    const options = {
+      agent: agent,
+      hostname: hostname,
+      path: pathname
+    };
+
+    https
+      .get(options, res => {
+        if (res.statusCode === 200) {
+          resolve(res.pipe(gunzip()).pipe(tar.extract()));
+        } else {
+          reject(res);
+        }
+      })
+      .on("error", reject);
+  });
+}
+
+module.exports = fetchNpmPackage;