chore: remove examples from lerna packages

[dyladan]

Which problem is this PR solving?

• Plugins won't load when linked via lerna #368 plugins fail to load if the examples are installed using lerna bootstrap due to a symlink module resolution issue require can't find module by name if it's a symlink anymore nodejs/help#1212

Short description of the changes

Examples fail to run if they are installed with the regular boostrap process.
Removing them from packages allows the user to npm install them
regularly.

If someone knows a reason to keep examples/* in the lerna packages please let me know so we can find a different workaround

[codecov-io]

Codecov Report

Merging #470 into master will decrease coverage by 0.11%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #470      +/-   ##
==========================================
- Coverage   95.26%   95.14%   -0.12%     
==========================================
  Files         137      136       -1     
  Lines        6840     6715     -125     
  Branches      597      591       -6     
==========================================
- Hits         6516     6389     -127     
- Misses        324      326       +2

Impacted Files	Coverage Δ
...-plugin-http/test/functionals/http-package.test.ts	95.45% <0%> (-4.55%)	⬇️
...entelemetry-exporter-jaeger/test/transform.test.ts	100% <0%> (ø)	⬆️
...ges/opentelemetry-exporter-zipkin/src/transform.ts	100% <0%> (ø)	⬆️
...telemetry-plugin-grpc/test/utils/assertionUtils.ts	100% <0%> (ø)	⬆️
.../opentelemetry-exporter-zipkin/test/zipkin.test.ts	100% <0%> (ø)	⬆️
.../opentelemetry-exporter-jaeger/test/jaeger.test.ts	100% <0%> (ø)	⬆️
packages/opentelemetry-web/src/WebTracer.ts	100% <0%> (ø)	⬆️
...entelemetry-exporter-zipkin/test/transform.test.ts	100% <0%> (ø)	⬆️
...opentelemetry-plugin-http/test/utils/assertSpan.ts	100% <0%> (ø)	⬆️
...ackages/opentelemetry-exporter-zipkin/src/utils.ts
... and 1 more

[mayurkale22]

One advantage of keeping examples/* in the lerna packages is when you bump the version, it will update the latest version in examples/* as well. Otherwise, you need to do it manually.

[dyladan]

We just need to find a way to exclude it from the lerna bootstrap process

[mayurkale22]

Actually, I am ok to remove examples/* from Lerna. Would like to hear more from others.

[markwolff]

This would also solve this issue #384 (comment)

[dyladan]

I think the additional burden of periodically updating dependencies in the examples is outweighed by the confusions new users will have when they can't load the examples using the instructions provided.

[dyladan]

Here is my attempt to explain why this is broken and suggest an alternative fix.

In the examples/http/node_modules/@opentelemetry folder there is a symlink named node which points too ../../../../packages/opentelemetry-node. When the example loads the @opentelemetry/node package, it is loaded in the packages/ directory, not the examples/node_modules/ directory. When the @opentelemetry-node package tries to require the plugin, it looks in the following directories on my machine:

[ '/Users/daniel.dyla/playground/opentelemetry/js/packages/opentelemetry-node/build/src/instrumentation/node_modules',
  '/Users/daniel.dyla/playground/opentelemetry/js/packages/opentelemetry-node/build/src/node_modules',
  '/Users/daniel.dyla/playground/opentelemetry/js/packages/opentelemetry-node/build/node_modules',
  '/Users/daniel.dyla/playground/opentelemetry/js/packages/opentelemetry-node/node_modules',
  '/Users/daniel.dyla/playground/opentelemetry/js/packages/node_modules',
  '/Users/daniel.dyla/playground/opentelemetry/js/node_modules',
  '/Users/daniel.dyla/playground/opentelemetry/node_modules',
  '/Users/daniel.dyla/playground/node_modules',
  '/Users/daniel.dyla/node_modules',
  '/Users/node_modules',
  '/node_modules' ]

none of these directories are '/Users/Daniel.dyla/playground/opentelemetry/js/examples/http/node_modules' which is where it should be looking. The require tree has been entirely moved into the packages directory from the examples directory. In a customer's installation, or if the example's dependencies are installed not using symlinks like this PR suggests, @opentelemetry/node exists in the same node_modules as the http plugin.

One alternative fix would be to install all plugin packages as dev dependencies in the root of the project, which is a parent of both directories.

[OlivierAlbertini]

I think the additional burden of periodically updating dependencies in the examples is outweighed by the confusions new users will have when they can't load the examples using the instructions provided.

Also once we will install greenkeeper tool (or other), it will check that for us

[danielkhan]

We are using lerna to allow package inter-dependencies during development.
The same applies to the examples folder.
Say - you just added a new feature and want to provide an example for it.

I saw the problem with the plugin loader - so this seems just not to work with lerna - and this is a valid point but I'm not sure if we should ditch the benefits for that.

If we go down that route, we should at least document a reliable way to solve this during development.