Support field customization

[jpage-godaddy]

Support customization of fields on a per-request basis

[cla-checker-service]

💚 CLA has been signed

[jpage-godaddy]

We've reportedly signed a contributor agreement; I'm not sure how to get it to be reflected here.

[jpage-godaddy]

Going to try closing and reopening

[trentm]

cla/check

[trentm]

@jpage-godaddy Regarding the CLA, my understanding is that you or someone at GoDaddy will need to send an email to cla-questions@elastic.co asking to add you to your corporate CLA. Per this on https://www.elastic.co/contributor-agreement

If you are a company with an existing contributor license agreement and would like to add or change the list of employees that are authorized to contribute, please email us at cla-questions@elastic.co.

I don't know how to verify on my end whether GoDaddy has a corporate CLA. Let me know if you hit a wall here and I can start asking around.

[trentm]

Running npm run lint:fix will fix the "lint" check failure.

You'll have to avoid the ??= syntax in the test to maintain the support back to node v10 that we currently support:

/home/runner/work/ecs-logging-nodejs/ecs-logging-nodejs/packages/ecs-morgan-format/test/basic.test.js:249
        fields.labels ??= {};
                      ^^^

SyntaxError: Unexpected token '??='
    at wrapSafe (internal/modules/cjs/loader.js:1029:16)
    ...

[trentm]

Thanks for the PR!

The https://github.com/elastic/ecs-logging-nodejs/blob/main/docs/morgan.asciidoc#reference docs file should get an update for this. I can help with that if you like -- no need for you to learn asciidoc just for this.

Another request/comment below.

[jpage-godaddy]

@trentm thanks for the review. I've made some updates and am ready for another pass.