[extension/storage/dbstorage] Create component

[atoulme]

Description:
Add an experimental dbstorage extension, similar to filestorage.

Supports Postgres and sqlite.

Sponsor: @dmitryax

• A complete config.go, which will show how your component will look like to users
• README.md with some basic information about your component
• versions.yaml
• CODEOWNERS with at least the sponsor and the component's author
• internal/components tests
• go.mod at the root of the repository and cmd/configschema
• dependabot
• The skeleton of the component, potentially using the helpers
• Makefile

Testing:
Unit tests.

Documentation:
README added

Fixes #7114

[dmitryax]

Hey @atoulme , we are in the process of introducing new guidelines for adding new component. Please check the this issue and add the checklist to this PR or create an issue.

You can add me as sponsor.

[dmitryax]

One nit. Otherwise LGTM

[jpkrohling]

LGTM, the clarification about how to extend a distribution to use a new driver can be part of a follow-up PR.

[jpkrohling]

How would it work concretely? I can't think of a clean way of doing that using the builder, and not using it means having to manage more than just an import statement. But perhaps I'm missing something?

[atoulme]

From what I get, folks building their own distros can add imports of additional drivers and import them using the underscore import, just like this SO thread explains: https://stackoverflow.com/questions/21220077/what-does-an-underscore-in-front-of-an-import-statement-mean
As long the init() function of those side-effect imports registers the driver, it should be fine.

[jpkrohling]

Right, but this import has to be in a source file that is included in the distribution. So, either a downstream distribution creates a whole new extension just for the import statement, or they have to maintain the source code for their distribution (main.go essentially) because of that import line. Or perhaps there's a better solution I'm not seeing?

[atoulme]

Yes, I guess they'd add that to their main.go? I just don't know any better, I'm sorry.

[jpkrohling]

Right -- they might just not have a main.go yet. I'm OK with approving and merging this as is, but would still be good to have an end-to-end example for users interested in extending with their SQL drivers.

[atoulme]

Would you please file an issue, sorry - especially interested in where such a sample would live?

[jpkrohling]

Done: #7157