Introduce different log levels

modules/utils/fetchNpmPackage.js

@@ -5,13 +5,16 @@ const tar = require("tar-stream");
 
 const bufferStream = require("./bufferStream");
 const agent = require("./registryAgent");
+const logging = require("./logging");
 
 function fetchNpmPackage(packageConfig) {
   return new Promise((resolve, reject) => {
     const tarballURL = packageConfig.dist.tarball;
 
-    console.log(
-      `info: Fetching package for ${packageConfig.name} from ${tarballURL}`
+    logging.debug(
+      "Fetching package for %s from %s",
+      packageConfig.name,
+      tarballURL
     );
 
     const { hostname, pathname } = url.parse(tarballURL);

modules/utils/fetchNpmPackageInfo.js

@@ -4,6 +4,7 @@ const https = require("https");
 const serverConfig = require("../serverConfig");
 const bufferStream = require("./bufferStream");
 const agent = require("./registryAgent");
+const logging = require("./logging");
 
 function parseJSON(res) {
   return bufferStream(res).then(JSON.parse);
@@ -18,9 +19,7 @@ function fetchNpmPackageInfo(packageName) {
 
     const infoURL = `${serverConfig.registryURL}/${encodedPackageName}`;
 
-    console.log(
-      `info: Fetching package info for ${packageName} from ${infoURL}`
-    );
+    logging.debug("Fetching package info for %s from %s", packageName, infoURL);
 
     const { hostname, pathname } = url.parse(infoURL);
     const options = {

modules/utils/logging.js

@@ -0,0 +1,24 @@
+const log = console.log.bind(console);
+
+function noop() {}
+
+let debug, info, warn;
+
+if (process.env.LOG_LEVEL === "none") {
+  debug = info = warn = noop;
+} else if (process.env.LOG_LEVEL === "debug") {
+  debug = info = warn = log;
+} else if (process.env.LOG_LEVEL === "warn") {
+  debug = info = noop;
+  warn = log;
+} else {
+  // default LOG_LEVEL = "info"
+  debug = noop;
+  info = warn = log;
+}
+
+module.exports = {
+  debug,
+  info,
+  warn
+};