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Comment by flowerlad | Hacker News Reader

We need a way to set multiple SSL certificates with overlapping duration. So if one certificate expires the backup certificate will become active. If the overlap is a couple of months then you have plenty of time to detect and fix the issue.

Having only one SSL certificate is a single point of failure, we have eliminated single points of failure almost everywhere else.

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You can do this pretty easily with Let’s Encrypt, to my knowledge. You can request resistance every 30 days, for example, which would give you a ladder of three 90 day certificates.

Edit: but to be clear, I don’t understand why you’d want this. If you’re worried about your CA going offline, you should shorten your renewal period instead.

Do services such as K8S ingress and Azure web apps allow you to specify multiple certificates?

Update: looks like the answer is yes. So then the issue is people not taking advantage of this technique.

I don’t think there’s a ton of benefit to the technique. If you’re worried about getting too close to your certificate expiry via automation, the solution is to renew earlier rather than complicate things with a ladder of valid certs.

Exactly. It's not like backup certificate have validity starting at a future date.

Yes the backup certificate can have validity starting at a future date. You just need to wait till that future date to create it.

There are reasons to do this, just not because of expiry.

The main reason to have multiple certs is so if your host (and cert prov key) is compromised, you can quickly switch to a backup, without first having to sort out getting a new cert issued.

If getting a new cert issued is some sort of thing you need to sort out, as in a process that takes time, you've already missed the target.

If you want a backup system its best if its self contained. When your site is down its easier to just run a single command to copy over a single file in your control instead of depending on an external service.

> We need a way to set multiple SSL certificates with overlapping duration.

Both Apache (SSLCertificateFile) and nginx (ssl_certificate) allow for multiple files, though they cannot be of the same algorithm: you can have one RSA, one ECC, etc, but not (say) an ECC and another ECC. (This may be a limitation of OpenSSL.)

So if the RSA expires on Feb 1, you can have the ECC expire on Feb 14 or Mar 1.

That's a lot of words coming from people who were against this very idea not that long ago. Before Let's Encrypt existed, 90% of you were violently against the idea. "No, that's not how it's supposed to work." That's how it was.

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