Support Openresty in the NGINX plugin (#5467)

* fixes #4919 openresty_support

* making the regex more general

* reformatting warning to pass lint

* Fix string formatting in logging function

* Fix LE_AUTO_VERSION

certbot-nginx/certbot_nginx/configurator.py

@@ -895,7 +895,7 @@ def get_version(self):
             raise errors.PluginError(
                 "Unable to run %s -V" % self.conf('ctl'))
 
-        version_regex = re.compile(r"nginx/([0-9\.]*)", re.IGNORECASE)
+        version_regex = re.compile(r"nginx version: ([^/]+)/([0-9\.]*)", re.IGNORECASE)
         version_matches = version_regex.findall(text)
 
         sni_regex = re.compile(r"TLS SNI support enabled", re.IGNORECASE)
@@ -912,7 +912,12 @@ def get_version(self):
         if not sni_matches:
             raise errors.PluginError("Nginx build doesn't support SNI")
 
-        nginx_version = tuple([int(i) for i in version_matches[0].split(".")])
+        product_name, product_version = version_matches[0]
+        if product_name is not 'nginx':
+            logger.warning("NGINX derivative %s is not officially supported by"
+                           " certbot", product_name)
+
+        nginx_version = tuple([int(i) for i in product_version.split(".")])
 
         # nginx < 0.8.48 uses machine hostname as default server_name instead of
         # the empty string