npm 7 (node 15/16) install fails on main in a fresh repo clone

[Flarna]

What version of OpenTelemetry are you using?

tip of main branch

What version of Node are you using?

14.16.0
edit: 15.14.0

Please provide the code you used to setup the OpenTelemetry SDK

What did you do?

npm install --no-package-lock

What did you expect to see?

successful lerna bootstrap

What did you see instead?

lerna info Bootstrapping 33 packages
lerna info Installing external dependencies
lerna ERR! npm install exited 1 in '@opentelemetry/api-metrics'
lerna ERR! npm install stderr:
npm ERR! code ERESOLVE
npm ERR! ERESOLVE unable to resolve dependency tree
npm ERR!
npm ERR! While resolving: @opentelemetry/api-metrics@0.18.2
npm ERR! Found: webpack@4.46.0
npm ERR! node_modules/webpack
npm ERR!   dev webpack@"4.46.0" from the root project
npm ERR!
npm ERR! Could not resolve dependency:
npm ERR! peer webpack@"^5.0.0" from karma-webpack@5.0.0
npm ERR! node_modules/karma-webpack
npm ERR!   dev karma-webpack@"5.0.0" from the root project
npm ERR!
npm ERR! Fix the upstream dependency conflict, or retry
npm ERR! this command with --force, or --legacy-peer-deps
npm ERR! to accept an incorrect (and potentially broken) dependency resolution.

Additional context

No idea why this doesn't occur in CI. Maybe because we have some cached package-lock.json fails.

Refs:
#1907 (update karma-webpack to v5)
#1598 (update webpack to 5.x - not yet merged)

[Flarna]

I accidentally used nodejs 15.14.0 which comes with npm 7. Looks like the changes done there regarding peer dependencies cause this.
This will be problematic once node.js 16 will be added to our test matrix.

[weyert]

Yeah, a --legacy-peer-deps would be a temporary solution. To me it looks like a lot of dependencies aren't ready for npm 7

[dyladan]

There's probably not much we can do until our deps are ready for npm 7

[Flarna]

I invested not that much time in this because I have more or less no experience with webpack and such tools.
I stopped at https://www.npmjs.com/package/istanbul-instrumenter-loader which seems to be a permanent blocker as it requires webpack 4.x but the github repo is archived therefore I guess we should not expect any updates.

I think we should start to find a replacement compatible with 5.x.

[vmarchaud]

I think we could switch to use NODE_V8_COVERAGE to collect coverage, however this is only available starting node 10: https://nodejs.org/dist/latest-v10.x/docs/api/cli.html#cli_node_v8_coverage_dir

[dyladan]

We could do a "best effort" to keep node 8 compatibility while not specifically using it in our testing infrastructure

[Flarna]

As far as I understood istanbul-instrumenter-loader is only used together with webpack so this seems to be more a browser thingy.

For node we use nyc which is still active maintained to my knowledge and works fine even with node 8.

[dyladan]

@Flarna is this still an issue? Going to close this as I think it is resolved but reopen if that is wrong.