A question about expires attribute of Order Resource

[test_mail_new]

After I finalize a order by send request with csr content to /finalize API.

Then I can get this response:

{
'Content-Length': '459',
 'Strict-Transport-Security': 'max-age=604800', 
'Cache-Control': 'public, max-age=0, no-cache',
 'Server': 'nginx',
 'Connection': 'keep-alive', 
'Link': '<https://acme-staging-v02.api.letsencrypt.org/directory>;rel="index"', 
'Location': 'https://acme-staging-v02.api.letsencrypt.org/acme/order/.../...', 
'Boulder-Requester': '17092284',
 'Date': 'Tue, 22 Dec 2020 03:52:47 GMT',
 'X-Frame-Options': 'DENY',
 'Content-Type': 'application/json', 
'Replay-Nonce': '0003NBeE3su_6fx2gelKMX6W6Wu7pLpevdEnd8OqWoYTII4'
}
{u'authorizations': [u'https://acme-staging-v02.api.letsencrypt.org/acme/authz-v3/....'],
 u'certificate': u'https://acme-staging-v02.api.letsencrypt.org/acme/cert/......',
 u'expires': u'2020-12-28T06:31:50Z',
 u'finalize': u'https://acme-staging-v02.api.letsencrypt.org/acme/finalize/...../....',
 u'identifiers': [{u'type': u'dns', u'value': .....'}],
 u'status': u'valid'}

PARAM: expires
is 2020-12-28T06:31:50Z .

I new this order at sometime of 2020-12-21.

Must I download the certificate before this time "2020-12-28T06:31:50Z "?

[griffin]

Once you successfully get a certificate generated, I'm not sure how long the certificate download link is valid. You can always download the certificate (and the intermediate certificate) anytime you want from https://crt.sh.

[test_mail_new]

Ok, I should download the certificate as soon as possible.

[aarongable]

Certificate download links are guaranteed to be valid for the entire lifetime of the certificate, which is significantly longer (90 days) than the lifetime of the order object (one week).

[rmbolger]

Just to be clear, that's a Boulder (as currently implemented) guarantee rather than an RFC 8555 protocol level guarantee, right? Like, that may not be the case with other ACME CAs?

[aarongable]

Correct, nothing in RFC8555 or other regulations mandates a length of time for those URLs to work.