Cert health check can use duration syntax for deadline param

[zachmargolis]

• Ex: /api/health/certs?deadline=7d

Why: This allows us to query the endpoint with fixed strings
for separate durations, so we could warn at a 30d expiration but
have a separate check that errors at a 7d expiration

Notes: I cribbed the DurationParser class I wrote in the IDP. It didn't seem worth forcing into a shared gem or anything, for reference, it's at: https://github.com/18F/identity-idp/blob/master/app/services/duration_parser.rb

[zachmargolis]

We had already disabled reek in #165, but this file stuck around. While tracking down the method complexity error CodeClimate error I found this and figured I'd remove it. Can do another PR if anybody feels strongly

[aduth]

I guess the switch fallthrough would have the same effect of generating a nil value, but... should we match on the specific duration characters we support?

Suggested change

	match = value.match(/^(?<number>\d+)(?<duration>\D)$/)
	match = value.match(/^(?<number>\d+)(?<duration>[dwmy])$/)

[zachmargolis]

My thinking was the switch fallthrough would be the easiest? If we ever add a new character we only need to add it on one place, also allows like multicharacter signifiers if we ever wanted to allow like hr and wk or something

[aduth]

My thinking was the switch fallthrough would be the easiest? If we ever add a new character we only need to add it on one place, also allows like multicharacter signifiers if we ever wanted to allow like hr and wk or something

Seems fine to me. And I just now noticed you have test coverage for this with the 123x example, so should be protected against accidental regressions. On that point, I guess my primary concern is not that the switch fallthrough doesn't work, just that it might not be as obvious to the next person that we're relying on it.

[aduth]

Are we okay that these aren't strictly accurate? e.g. months with fewer or more than 30 days, or leap years.

Would it work to just...

Suggested change

	when 'w' # weeks
	(7 * number).days
	when 'm' # months
	(30 * number).days
	when 'y' # years
	(365 * number).days
	when 'w' # weeks
	number.weeks
	when 'm' # months
	number.months
	when 'y' # years
	number.years

[zachmargolis]

When originally implementing this I decided to make it simpler/dumber so I could easily document it:

See verified_within (inside the details dropdown) on https://developers.login.gov/oidc/

The ActiveSupport methods are very nice but they use fractional quantities for some of those so it seemed more predictable this way (so when the fractional quantities add up they don't change hours/minutes as much)

1.years.to_i.to_f / 1.day.to_i
=> 365.2425

I feel somewhat strongly about leaving it simpler and documented, but if you feel strongly, I could change it here and discuss changing the IDP with the rest of the team

[aduth]

I feel somewhat strongly about leaving it simpler and documented, but if you feel strongly, I could change it here and discuss changing the IDP with the rest of the team

I don't feel strongly.

👍