Adjust the `checkIfOnline` check if in a corporate proxy environment #2884

bsyk · 2017-08-01T18:21:20Z

Adjust the checkIfOnline check if in a corporate proxy environment
If the environment variable https_proxy is set, test that the proxy name is resolveable rather than 'registry.yarnpkg.com'.

Testing on a corporate network where proxies are required. Prior to change, installation fails as per #2832, post change installation works happily.

Before:

After with proxy set & required:

After with proxy not set, but required:

After with proxy set incorrectly:

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Timer · 2017-08-02T00:17:31Z

packages/create-react-app/createReactApp.js

@@ -606,7 +606,7 @@ function isSafeToCreateProjectIn(root, name) {
 }

 function checkIfOnline(useYarn) {
-  if (!useYarn) {
+  if (!useYarn || process.env.https_proxy) {


I'm not sure if skipping this check when proxy is defined is the best course of action -- can we try to resolve the URL through the proxy instead?

That was my first thought too. However, to test whether yarn has access vs the node process has access are quite different things and one doesn't necessarily prove the other.
Similarly, being able to resolve the address in DNS doesn't prove yarn will work either, which made me consider the purpose of this check. My conclusion was that this is an aid to make a best effort if there isn't an internet connection.
My thinking from there was that in its current state, you can't use create-react-app if you need a proxy, regardless of settings. With this change at worst you'll get a different error.

What about extracting the hostname from https_proxy and looking that up?

That seems reasonable, I'll make the change this morning.
Thinking out loud: What if the proxy is specified by IP?

Good point. Seems fine:

> dns.lookup('127.0.0.1', console.log) {} > null '127.0.0.1' 4 > dns.lookup('10.5.3.2', console.log) {} > null '10.5.3.2' 4

Great, thanks for checking. I'll update in a couple of hours.

If the environment variable `https_proxy` is set, test that the proxy name is resolveable rather than 'registry.yarnpkg.com'. This fixes facebook#2832.

Timer · 2017-08-06T04:16:01Z

packages/create-react-app/createReactApp.js

+    if (process.env.https_proxy) {
+      host = url.parse(process.env.https_proxy).hostname;
+    }
+    dns.lookup(host, err => {
      resolve(err === null);


While we're here, this strict equality in this case makes me uncomfortable -- can we do == null?

Timer · 2017-08-06T04:34:20Z

Neat, thanks for fixing that so quick!

Does this fix it for you when running it locally with the patch installed by hand?

bsyk · 2017-08-06T04:36:03Z

Yes. I tested by calling the script directly, rather than the globally installed version.
Screenshots are in the first PR comment.

Timer · 2017-08-06T04:43:59Z

Hmm, I wonder if we should always test registry.yarnpkg.com first, followed by proxy if set.
I'm not sure of edge cases we might want to account for, and I like to be careful with the global CLI.

What do you think?

bsyk · 2017-08-06T04:49:11Z

I agree with the caution. Proxies and people's configurations are always troublesome.
Seems like a decent approach to try yarn first, then if that fails and a proxy is set to try the proxy.

Timer · 2017-08-07T00:58:35Z

packages/create-react-app/createReactApp.js

@@ -614,7 +615,15 @@ function checkIfOnline(useYarn) {

  return new Promise(resolve => {
    dns.lookup('registry.yarnpkg.com', err => {
-      resolve(err === null);
+      if (err && process.env.https_proxy) {


I'd like this to be err != null.

…if that failed

Timer · 2017-08-09T01:36:28Z

Great, thanks so much for this!

Timer · 2017-08-09T03:49:01Z

Hi there! This change is out in [email protected]; please give it a go! Thanks.

bsyk · 2017-08-09T03:50:45Z

Great. I'll update first thing tomorrow.
Thanks for your thoughts on this.

Timer · 2017-08-09T03:51:30Z

Well, I guess in this case [email protected]. 😄

…(#2884) * Adjust the `checkIfOnline` check if in a corporate proxy environment If the environment variable `https_proxy` is set, test that the proxy name is resolveable rather than 'registry.yarnpkg.com'. This fixes #2832. * Adjust to check yarnpkg.com first, then check the proxy address only if that failed

* commit 'bfaee410c502a95076a6bd89721c76ca08e15f7b': (39 commits) Publish Prepare for 1.0.11 release (facebook#2924) Update dev deps (facebook#2923) Update README.md Use env variable to disable source maps (facebook#2818) Make formatWebpackMessages return all messages (facebook#2834) Adjust the `checkIfOnline` check if in a corporate proxy environment (facebook#2884) Fix the order of arguments in spawned child proc (facebook#2913) Feature/webpack 3 4 (facebook#2875) Allow importing package.json (facebook#2468) Re-enable flowtype warning (facebook#2718) Format UglifyJs error (facebook#2650) Unstage yarn.lock pre-commit (facebook#2700) Update README.md Update README.md Add Electrode to alternatives (facebook#2728) Fix parsing HTML/JSX tags to real elements (facebook#2796) Update webpack version note (facebook#2798) Use modern syntax feature (facebook#2873) Allow use of scoped packages with a pinned version (facebook#2853) ... # Conflicts: # packages/react-scripts/config/webpack.config.dev.js # packages/react-scripts/config/webpack.config.prod.js # packages/react-scripts/package.json

…react-app * 'master' of https://github.com/facebookincubator/create-react-app: (36 commits) Publish Changelog for 1.0.12 (facebook#3016) Relax React dep requirements Default Favicon lossless optimisation (facebook#2917) update babel-runtime dependency in react-error-overlay and react-scripts (facebook#2991) Convert react-error-overlay to React (facebook#2515) Bump react-dev-utils Fix module function name in error overlay (facebook#3012) Docs: debugging in WebStorm (facebook#2986) Fix docs for `printFileSizesAfterBuild` (facebook#2942) Remove Modulus from user guide (facebook#2948) Remove superfluous lodash usage (facebook#2938) Update README.md (facebook#2927) Publish Prepare for 1.0.11 release (facebook#2924) Update dev deps (facebook#2923) Update README.md Use env variable to disable source maps (facebook#2818) Make formatWebpackMessages return all messages (facebook#2834) Adjust the `checkIfOnline` check if in a corporate proxy environment (facebook#2884) ...

…(#2884) * Adjust the `checkIfOnline` check if in a corporate proxy environment If the environment variable `https_proxy` is set, test that the proxy name is resolveable rather than 'registry.yarnpkg.com'. This fixes #2832. * Adjust to check yarnpkg.com first, then check the proxy address only if that failed

…acebook#2884) * Adjust the `checkIfOnline` check if in a corporate proxy environment If the environment variable `https_proxy` is set, test that the proxy name is resolveable rather than 'registry.yarnpkg.com'. This fixes facebook#2832. * Adjust to check yarnpkg.com first, then check the proxy address only if that failed

…(#2884) * Adjust the `checkIfOnline` check if in a corporate proxy environment If the environment variable `https_proxy` is set, test that the proxy name is resolveable rather than 'registry.yarnpkg.com'. This fixes #2832. * Adjust to check yarnpkg.com first, then check the proxy address only if that failed

herebebeasties · 2017-12-22T13:14:18Z

This is insufficient in some corp environments, where they run an internal registry with no direct access to the Internet even via a proxy (and thus the check should be against whatever URL yarn's registry config value is set to, which can be picked up from a large number of places, but which you could obviously parse via yarn config get registry).

That said, I don't understand why this offline check code exists in the first place - yarn will already use its local cache if the network is unavailable so you shouldn't need to add the --offline flag or have to do this check at all?

facebook-github-bot added the CLA Signed label Aug 1, 2017

Timer reviewed Aug 2, 2017

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Adjust the checkIfOnline check if in a corporate proxy environment

235739e

If the environment variable `https_proxy` is set, test that the proxy name is resolveable rather than 'registry.yarnpkg.com'. This fixes facebook#2832.

bsyk force-pushed the master branch from 226f810 to 235739e Compare August 2, 2017 16:45

bsyk changed the title ~~Bypass the checkIfOnline check if in a corporate proxy environment~~ Adjust the checkIfOnline check if in a corporate proxy environment Aug 2, 2017

Timer reviewed Aug 6, 2017

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Timer added the tag: bug fix label Aug 6, 2017

Timer added this to the 1.0.11 milestone Aug 6, 2017

Timer reviewed Aug 7, 2017

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Adjust to check yarnpkg.com first, then check the proxy address only …

99c4ab1

…if that failed

bsyk force-pushed the master branch from 05f832b to 99c4ab1 Compare August 7, 2017 01:03

Timer merged commit d009a99 into facebook:master Aug 9, 2017

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Adjust the `checkIfOnline` check if in a corporate proxy environment #2884

Adjust the `checkIfOnline` check if in a corporate proxy environment #2884

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Adjust the checkIfOnline check if in a corporate proxy environment #2884

Adjust the checkIfOnline check if in a corporate proxy environment #2884

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Adjust the `checkIfOnline` check if in a corporate proxy environment #2884

Adjust the `checkIfOnline` check if in a corporate proxy environment #2884

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