Description

What is changing?

• Adds getFaasEnv() that gathers environment information as specified
  • https://github.com/mongodb/specifications/blob/master/source/mongodb-handshake/handshake.rst#client-env
• Modifies makeClientMetadata to build the metadata document with an es map that checks the BSON size of every input preventing us from exceeding 512 bytes
  • Map offers a few conveniences over objects: key iteration, element count, set/delete is typical method syntax rather than bracket notation
• Introduces an error if driverInfo properties name/version/platform use up the 512 bytes, this would prevent us from having a helloDoc.client.driver.name property which is required server side
• if metadata document is at capacity, we will attempt to remove fields from os until it can fit, followed by the same logic for env
  • We do predict this is unlikely, but the hard restriction is that we never construct a document larger than 512 bytes.

Is there new documentation needed for these changes?

No mongodb manual changes.

I changed the API docs above MongoOptions, this is made public by the client.options getter and represents the parsed options, the type isn't necessarily an accurate representation of the runtime value because there are properties that are set after SRV lookup.

What is the motivation for this change?

FaaS environments have a unique impact on the driver's approach to it's distributed systems logic (SDAM). If we can better understand the environments & resources being used we can provide the best FaaS experience possible.

Double check the following

• Ran npm run check:lint script
• Self-review completed using the steps outlined here
• PR title follows the correct format: type(NODE-xxxx)[!]: description
  • Example: feat(NODE-1234)!: rewriting everything in coffeescript
• Changes are covered by tests
• New TODOs have a related JIRA ticket