yarn modules-folder parameter reveal >>>Error: Cannot find module 'mkdirp'<<<

[stopsopa]

about modules-folder

Error doesn't happen with other libraries, for example lodash

Environment:

node: v6.10.0
npm: 3.10.10
yarn: v0.21.3

Steps to reproduce error:

D:\www>mkdir test

D:\www>cd test

D:\www\test>yarn add node-sass
yarn add v0.21.3
info No lockfile found.
[1/4] Resolving packages...
[2/4] Fetching packages...
[3/4] Linking dependencies...
[4/4] Building fresh packages...
success Saved lockfile.
success Saved 173 new dependencies.
├─ abbrev@1.1.0
├─ ajv@4.11.8
├─ amdefine@1.0.1
├─ ansi-regex@2.1.1
├─ ansi-styles@2.2.1
├─ .
├─ ..
├─ ...
├─ y18n@3.2.1
├─ yallist@2.1.2
├─ yargs-parser@5.0.0
└─ yargs@7.1.0
Done in 7.11s.

D:\www\test>dir
 Volume in drive D is Magazyn
 Volume Serial Number is 54AB-00D8

 Directory of D:\www\test

2017-07-22  10:17 PM    <DIR>          .
2017-07-22  10:17 PM    <DIR>          ..
2017-07-22  10:17 PM    <DIR>          node_modules
2017-07-22  10:17 PM                59 package.json
2017-07-22  10:17 PM            36,046 yarn.lock
               2 File(s)         36,105 bytes
               3 Dir(s)  32,325,296,128 bytes free

D:\www\test>rm -rf node_modules

D:\www\test>yarn install --modules-folder=public
yarn install v0.21.3
warning No license field
[1/4] Resolving packages...
[2/4] Fetching packages...
[3/4] Linking dependencies...
[4/4] Building fresh packages...
[1/1] ⠄ node-sass
[-/1] ⠄ waiting...
[-/1] ⠄ waiting...
[-/1] ⠄ waiting...
error public\node-sass: Command failed.
Exit code: 1
Command: C:\WINDOWS\system32\cmd.exe
Arguments: /d /s /c node scripts/install.js
Directory: public\node-sass
Output:
module.js:471
    throw err;
    ^

Error: Cannot find module 'mkdirp'
    at Function.Module._resolveFilename (module.js:469:15)
    at Function.Module._load (module.js:417:25)
    at Module.require (module.js:497:17)
    at require (internal/module.js:20:19)
    at Object.<anonymous> (D:\www\test\public\node-sass\scripts\install.js:7:11)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)
info Visit https://yarnpkg.com/en/docs/cli/install for documentation about this command.

D:\www\test>

[saper]

I am assuming you are getting node-sass v4.5.3 ? Your log does not seem to be saying that.

Our install.js is using normal require('mkdirp') which is a node feature that works since the early days.

Even after reading yarnpkg/yarn#1684 I have no idea what is the purpose of this option; it seems that everybody seems to use node_modules as a part of their path, like in

yarn install --modules-folder=public/node_modules

node_modules is hardcoded in node and there is no way to override that. npm refused to implement anything to change that directory for npm npm/npm#775

Feel free to ask yarnpkg/yarn#1684 for more details, but I would refrain from using this option if it is not understood well.

[stopsopa]

Yes, seems that there is no other way to tell node to load by default libraries from other directory then from node_modules but by changing global variable process.env.NODE_PATH. And problems with that reveals on node-sass but not on lodash because node-sass has scripts that runs immediately after instalation. Lodash don't have it.

Because this script is working on unchanged environment (without redirected NODE_PATH) that's why it can't find mkdirp library.

Took me a while to find that, and in the process i thought that this is error of node-sass itself, but is not.

Solution is to change NODE_PATH and then install libraries, like:

for /f "tokens=*" %a in ('echo %cd%\public') do @set NODE_PATH=%a
echo %NODE_PATH%
yarn install --modules-folder=public

And because of that, actually this problem is not related with yarn at all, it's probably gonna happen with npm install as well.

Thank you for help anyway.

[saper]

Thanks for bringing this to out attention, I didn't know yarn can do this. Npm cannot.

[nageshjawanjal]

create new project of same version and then go to node_modules copy "mkdirp" folder and paste it to your Project's node_module folder

[tranhl]

@saper I'm not sure about other people, but I typically use --modules-folder during multistage Docker builds to cache dependency installation. It allows me to install both the dependencies needed for the build process, as well as the production dependencies, earlier in the build process, which significantly improves build time (from 3 mins to ~10 seconds).

For example:

RUN yarn install --prod --link-duplicates --modules-folder ./prod_node_modules
RUN yarn install --modules-folder ./node_modules