Use a singleton for the DB connection object

[Vinnl]

References:

Jira: MNTOR-3606
Figma:

Description

This is the riskier sibling to #5254, where I'm trying to figure out what could be causing the monthly-activity-free cronjob to be hanging.

In this PR, I call destroy() on the connection object when it's done - but more importantly, I have every db/tables module re-use the same connection object, to avoid having to do this:

blurts-server/src/scripts/cronjobs/emailBreachAlerts.tsx

Lines 427 to 429 in 0da0296

	await knexSubscribers.destroy();
	await knexEmailAddresses.destroy();
	await knexHibp.destroy();

I think this should be safe, and in practice, the connections should be pooled already, but there might always be unforeseen effects, so please take some time to think about potential problems and/or ways to catch any that might occur.

[github-actions]

Preview URL 🚀 : https://blurts-server-pr-5257-mgjlpikfea-uk.a.run.app

[rhelmer]

Yes I think this is a better approach here. Could you please file a ticket to refactor the rest of the code to use this approach?

[Vinnl]

@rhelmer

Could you please file a ticket to refactor the rest of the code to use this approach?

The risky bit is that this already ensures all /db/tables/* files to re-use that singleton (because they call the createDbConnection function that I modified), so I think the rest of the code already is adapted. Or do you mean updating the rest of the .destroy() calls?

[github-actions]

Preview URL 🚀 : https://blurts-server-pr-5257-mgjlpikfea-uk.a.run.app

[github-actions]

Cleanup completed - database 'blurts-server-pr-5257' destroyed, cloud run service 'blurts-server-pr-5257' destroyed

[rhelmer]

@rhelmer

Could you please file a ticket to refactor the rest of the code to use this approach?

The risky bit is that this already ensures all /db/tables/* files to re-use that singleton (because they call the createDbConnection function that I modified), so I think the rest of the code already is adapted. Or do you mean updating the rest of the .destroy() calls?

Yes thinking of e.g.

blurts-server/src/scripts/cronjobs/emailBreachAlerts.tsx

Lines 427 to 429 in c2e3402

	await knexSubscribers.destroy();
	await knexEmailAddresses.destroy();
	await knexHibp.destroy();

- I wonder if we could expose this destroy method to the scripts so they have a simpler way to make sure everything is closed.