Add 30 day certificatesDuration step

[luker983]

What does this PR do?

Adds a new certificatesDuration threshold, setting renew period and renew interval to 10 days and 12 hours respectively when 30 days <= certificatesDuration < 90 days.

Motivation

There is a large gap between the 7 and 90 day certificatesDuration thresholds that has made Traefik difficult to adopt in environments that issue certificates with lifetimes shorter than 90 days.

With the current thresholds, 7-30 day cert lifetimes must either renew daily (straining the ACME CA), or only on the day before expiry (leaving little time to resolve an issue if renewal fails)

More

• Added/updated tests
• Added/updated documentation

Additional Notes

Ideally the renewal values would be directly configurable as they are in most ACME clients, but I understand the desire for a simpler config. If maintainers are up for opening that discussion again I would prefer to go that route 😄

[rtribotte]

Hello @luker983,

Thanks for opening this pull request!

We have marked thus as a need-design because we suspect it may introduce a breaking change for some users.
Since no issue was opened beforehand to discuss the possibility of such a change, we would welcome any feedback from the community.

[rtribotte]

After a second though, I moved it to `needs-review' because I actually think this is a good enhancement, that modifies the renewal mechanism, but in a way that should be harmless and beneficial.

[rtribotte]

Thanks 👍

[kevinpollet]

Thanks 👍