fix(opentelemetry-node): fix types to be on the ./sdk entry-point where they are to be used

[trentm]

For clarity (I hope) I've moved the lib/index.js to lib/sdk.js to
match the entry-point name. THis adds a small test case ensuring
a TypeScript 5 project is able to use @elastic/opentelemetry-node.

---

@david-luna This differs a bit from what we pair-programmed:

1. I move index.js to sdk.js to be the entry-point, rather than moving elastic-node-sdk.js and dropping index.js.
2. I found that the TS project (test/fixtures/a-ts-proj), needs to use TS 5 for the ".../sdk" entry-point to work. When we were looking at this, we had only verified that the types worked in VSCode. I believe VSCode is using its own internal TS 5. When running npx tsc on the CLI it failed. So I think this means we **want to set a min-supported TS version of v5, at least to use the ".../sdk" entry-point.

the failure with 'npx tsc'

[14:28:30 trentm@peach:~/tmp/asdf.20241122T111719]
% npx tsc
src/index.ts:1:23 - error TS2307: Cannot find module '@elastic/opentelemetry-node/sdk' or its corresponding type declarations.

1 import * as etel from '@elastic/opentelemetry-node/sdk';
                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tsconfig.json:27:15 - error TS6046: Argument for '--module' option must be: 'none', 'commonjs', 'amd', 'system', 'umd', 'es6', 'es2015', 'es2020', 'esnext'.

27     "module": "node16",                                /* Specify what module code is generated. */
                 ~~~~~~~~


Found 2 errors.

---

Here is what the added test case looks like before the fix, i.e. showing that is fails as we expected:

test failure (before the fix was applied)

% node typescript-usage.test.js
TAP version 13
# typescript usage
not ok 1 "npm start" in "./fixtures/a-ts-proj" succeeded
  ---
    operator: error
    at: <anonymous> (/Users/trentm/el/elastic-otel-node5/packages/opentelemetry-node/test/typescript-usage.test.js:31:15)
    stack: |-
      Error: Command failed: npm start

          at ChildProcess.exithandler (node:child_process:422:12)
          at ChildProcess.emit (node:events:517:28)
          at maybeClose (node:internal/child_process:1098:16)
          at ChildProcess._handle.onexit (node:internal/child_process:303:5)
  ...
# $ npm start
# -- stdout --
#
# > [email protected] start
# > npm install && tsc && node index.js
#
#
# up to date, audited 740 packages in 729ms
#
# 98 packages are looking for funding
# run `npm fund` for details
#
# found 0 vulnerabilities
# index.ts(2,53): error TS2307: Cannot find module '@elastic/opentelemetry-node/sdk' or its corresponding type declarations.
#
# -- stderr --
#
# --

1..1
# tests 1
# pass  0
# fail  1

[david-luna]

Hi @trentm

I found that the TS project (test/fixtures/a-ts-proj), needs to use TS 5 for the ".../sdk" entry-point to work.

This is due to the module compiler option feature. I did a bit of research and found that it was added in [email protected] release. Here are the notes https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-7.html#ecmascript-module-support-in-nodejs

User apps must have this feat to be able to resolve the exports from our package. We can say that min version required of TypeScript is ^4.7.2 (1st 4.7 released) which was release more that 2 years ago. IMHO its okay to also support below 5.x

npm view typescript time 
...
 '4.7.2': '2022-05-24T18:38:10.371Z',
...

Here's the diff after doing the checks, I've added @types/node for completeness although is getting the types from the node_modules at the root level

git diff
diff --git a/packages/opentelemetry-node/test/fixtures/a-ts-proj/package.json b/packages/opentelemetry-node/test/fixtures/a-ts-proj/package.json
index b939929..b755e65 100644
--- a/packages/opentelemetry-node/test/fixtures/a-ts-proj/package.json
+++ b/packages/opentelemetry-node/test/fixtures/a-ts-proj/package.json
@@ -8,7 +8,8 @@
   },
   "license": "Apache-2.0",
   "devDependencies": {
-    "typescript": "^5.0.2"
+    "@types/node": "^22.9.3",
+    "typescript": "^4.7.2"
   },
   "dependencies": {
     "@elastic/opentelemetry-node": "file:../../.."

[david-luna]

The fix is good. Let's decide on the TS version later

[david-luna]

should we create an issue for that?

[trentm]

Nah. :) At least I won't bother. The odd TODO for low-priority and clear nice-to-haves in the code is fine by me. I don't object to one being created, however.