feat: Add db.instance.id attribute

[arielvalentin]

Fixes # N/A

Changes

At GitHub we run MySQL in multi-node clusters and are often interested in knowing the hostname of a node that is executing a query or command.

In order to acheive this we added an attribute to the Trilogy instrumentation named db.mysql.instance.address which is populated with the hostname of the node:

open-telemetry/opentelemetry-ruby-contrib#487

This change adds the attribute to the database model as a MySQL specific connection attribute.

Merge requirement checklist

• CONTRIBUTING.md guidelines followed.
• CHANGELOG.md updated for non-trivial changes.
• schema-next.yaml updated with changes to existing conventions.

[arielvalentin]

@pyohannes @AlexanderWert Is there something more that you need from me? Are you wanting to explore the route of generic attribute naming?

[Oberon00]

As I understand the new server/client.address conventions

The hostname of the MySQL server instance bound to the current connection. This is useful in cases where the client is connecting to a MySQL server via a proxy or in a clustered environment

This should be filled in in server.address. The current definition of server.address might need to be / have already implicitly changed. See #342.

CC @trask @lmolkova It seems to me that the new address conventions should make this PR redundant, maybe this request could inform / validate the design of #342.

[pyohannes]

@Oberon00

This should be filled in in server.address. The current definition of server.address might need to be / have already implicitly changed. See #342.

I had the same thought, but there's more to it: #345 (comment):

Got it, so db.mysql.instance.address will identify the node inside the MySQL cluster. And server.address will be the address the user connects to.

[arielvalentin]

cc: @cschleiden @andyedison @adrianna-chang-shopify @open-telemetry/ruby-contrib-approvers

[AlexanderWert]

See my inline comment regarding the name of the generic attribute.

Please, also resolve the conflicts and update this PR as some of the previous fields have changed (e.g. server.socket.address).

[arielvalentin]

@AlexanderWert I have rebased and resolved conflicts as well as renamed the attribute to db.instance.id.

[AlexanderWert]

Nit: a small suggestion on the wording to make clear this field can contain any type of identifier (address, unique name, ids, etc.)

[arielvalentin]

@AlexanderWert thanks again for the review I have rebased and fixed the latest conflicts introduced by the registry refactoring.

Is there anything else that I need to do?

[AlexanderWert]

@AlexanderWert thanks again for the review I have rebased and fixed the latest conflicts introduced by the registry refactoring.

Is there anything else that I need to do?

LGTM!

We just need more approvals.