Feature request: Allow nginx to skip missing SSL certificate files instead of failing to start #913
Description
Describe the feature you'd like to add to nginx
A functionality that skips the error in case any SSL certificate or file does not exist.
Describe the problem this feature solves
There has already been an issue where, if one SSL certificate was missing (the file did not exist any more), the entire nginx web server refused to start. Free SSL certificates are often issued for only 3 months, and users frequently add and remove domains, which also adds or removes SSL certificates (files). It has happened that an SSL certificate no longer existed when nginx tried to start. This caused the following error:
nginx: [emerg] cannot load certificate "...": BIO_new_file() failed (SSL: error:02001002:system library:fopen:No such file or directory:fopen('...','r') error:2006D080:BIO routines:BIO_new_file:no such file)
The solution would allow nginx to start even if a particular SSL certificate (file) does not exist. In such a case, only that specific site would fail with wrong SSL certificate, but not the entire web server.
Additional context
A single missing SSL certificate should not prevent the entire web server from running.