npm ci outputs errors with angular 8 and node 12 on Windows: node-gyp rebuild

Question

My setup:

• Windows 10
• NVM 1.1.7 for Windows
• node 12.14.1 with npm 6.13.4
• Angular 8.2.14 with @angular/cli 8.3.22

Just trying to run the default angular template:

> npm install -g @angular/cli # this installed the angular version mentioned above
> ng new test # Chose default options for the project
> cd test
> npm ci # lots of error messages

The last command results in lots of errors in the output (but does not fail the command):

> [email protected] install C:\test\node_modules\@angular\compiler-cli\node_modules\fsevents
> node-gyp rebuild


C:\test\node_modules\@angular\compiler-cli\node_modules\fsevents>if not defined npm_config_node_gyp (node "C:\Users\foo\AppData\Roaming\nvm\v12.14.1\node_modules\npm\node_modules\npm-lifecycle\node-gyp-bin\\..\..\node_modules\node-gyp\bin\node-gyp.js" rebuild )  else (node "C:\Users\foo\AppData\Roaming\nvm\v12.14.1\node_modules\npm\node_modules\node-gyp\bin\node-gyp.js" rebuild )
gyp ERR! find Python
gyp ERR! find Python Python is not set from command line or npm configuration
gyp ERR! find Python Python is not set from environment variable PYTHON
gyp ERR! find Python checking if "python" can be used
gyp ERR! find Python - "python" is not in PATH or produced an error
gyp ERR! find Python checking if "python2" can be used
gyp ERR! find Python - "python2" is not in PATH or produced an error
gyp ERR! find Python checking if "python3" can be used
gyp ERR! find Python - "python3" is not in PATH or produced an error
gyp ERR! find Python checking if the py launcher can be used to find Python 2
gyp ERR! find Python - "py.exe" is not in PATH or produced an error
gyp ERR! find Python checking if Python is C:\Python27\python.exe
gyp ERR! find Python - "C:\Python27\python.exe" could not be run
gyp ERR! find Python checking if Python is C:\Python37\python.exe
gyp ERR! find Python - "C:\Python37\python.exe" could not be run
gyp ERR! find Python
gyp ERR! find Python **********************************************************
gyp ERR! find Python You need to install the latest version of Python.
gyp ERR! find Python Node-gyp should be able to find and use Python. If not,
gyp ERR! find Python you can try one of the following options:
gyp ERR! find Python - Use the switch --python="C:\Path\To\python.exe"
gyp ERR! find Python   (accepted by both node-gyp and npm)
gyp ERR! find Python - Set the environment variable PYTHON
gyp ERR! find Python - Set the npm configuration variable python:
gyp ERR! find Python   npm config set python "C:\Path\To\python.exe"
gyp ERR! find Python For more information consult the documentation at:
gyp ERR! find Python https://github.com/nodejs/node-gyp#installation
gyp ERR! find Python **********************************************************
gyp ERR! find Python
gyp ERR! configure error
gyp ERR! stack Error: Could not find any Python installation to use
gyp ERR! stack     at PythonFinder.fail (C:\Users\foo\AppData\Roaming\nvm\v12.14.1\node_modules\npm\node_modules\node-gyp\lib\find-python.js:307:47)
gyp ERR! stack     at PythonFinder.runChecks (C:\Users\foo\AppData\Roaming\nvm\v12.14.1\node_modules\npm\node_modules\node-gyp\lib\find-python.js:136:21)
gyp ERR! stack     at PythonFinder.<anonymous> (C:\Users\foo\AppData\Roaming\nvm\v12.14.1\node_modules\npm\node_modules\node-gyp\lib\find-python.js:225:16)
gyp ERR! stack     at PythonFinder.execFileCallback (C:\Users\foo\AppData\Roaming\nvm\v12.14.1\node_modules\npm\node_modules\node-gyp\lib\find-python.js:271:16)
gyp ERR! stack     at exithandler (child_process.js:302:5)
gyp ERR! stack     at ChildProcess.errorhandler (child_process.js:314:5)
gyp ERR! stack     at ChildProcess.emit (events.js:223:5)
gyp ERR! stack     at Process.ChildProcess._handle.onexit (internal/child_process.js:270:12)
gyp ERR! stack     at onErrorNT (internal/child_process.js:456:16)
gyp ERR! stack     at processTicksAndRejections (internal/process/task_queues.js:81:21)
gyp ERR! System Windows_NT 10.0.18362
gyp ERR! command "C:\\Program Files\\nodejs\\node.exe" "C:\\Users\\foo\\AppData\\Roaming\\nvm\\v12.14.1\\node_modules\\npm\\node_modules\\node-gyp\\bin\\node-gyp.js" "rebuild"
gyp ERR! cwd C:\Users\foo\repos\POC\angular\test1\node_modules\@angular\compiler-cli\node_modules\fsevents
gyp ERR! node -v v12.14.1
gyp ERR! node-gyp -v v5.0.5
gyp ERR!

All errors are related to fsevents, node-gyp and python executable not being found. That's right, I don't have python installed, but it's not a prerequisite for angular.

The command actually exits with a 0 code (indicating success - besides, ng build --prod works after that!) but there surely are a lot of errors in the output.

Deleting the node_modules folder manually and running npm install instead of npm ci produces an output which is a lot shorter and without any error. Also, it does not modify the package-lock.json file, which indicates that the same versions of the dependencies are installed.

What is going on? Why so many errors when using npm ci but none when using npm install?

Answer 1

It seems the bug is related to this issue and this issue.

Angular indirectly depends on fsevents 1.2.11, which is not supposed to be compiled on Windows (it's a darwin-OS related module). npm ci is bugged and ignores the os field in the module's package.json, so it tries to compile the module anyway, which fails on Windows.

The error did not occur in previous angular versions because fsevents 1.2.9 was directly downloading binaries from AWS instead of compiling them. But due to a loss of access from the devs to the AWS bucket, leading to the impossibility to install the module on node 13, they released the 1.2.11 patch to allow node 13 users to install the package.

Until npm ci gets fixed and/or fsevents gets updated to 2.x in angular, the workarounds on Windows are either:

• Just ignore the error. npm ci exits wit code 0 because the dependency is optional, so it should not block your deployment script (just slow it down a bit and make it more verbose). The least bad option in my opinion...
• Use npm install instead of npm ci, which will correctly process the os field of fsevents dependencies file. But this will potentially update your dependencies, so it is not really suitable for CI scripts, as it can change versioned files, and does not produce a repeatable output.
• Lock the fsevents module version to 1.2.9 instead of 1.2.11 in your dependencies file, so that npm ci downloads the binaries instead of compiling them. This won't work when using node 13, as there are no binaries to download for this version of node. Also, I could not find how one should update the package.json file to do that (this didn't work for me).
• Use npm ci --no-optional. Unfortunately this doesn't work, because of yet another bug in npm ci.