Appwrite use multiple hosts and IPs for their API and also use CDN for faster cached objects.
for example "cloud.appwrite.io" (the Console UI) have thoses IPs (looks like CF):
;; ANSWER SECTION:
cloud.appwrite.io. 300 IN A 104.20.22.179
cloud.appwrite.io. 300 IN A 172.66.168.42
while the FRA region API use thoses IPs:
;; ANSWER SECTION:
fra.cloud.appwrite.io. 218 IN CNAME fastly.appwrite.systems.
fastly.appwrite.systems. 38 IN A 151.101.67.52
fastly.appwrite.systems. 38 IN A 151.101.131.52
fastly.appwrite.systems. 38 IN A 151.101.195.52
fastly.appwrite.systems. 38 IN A 151.101.3.52
Tho you could :
- add the complete IP range of appwrite (tho i don't know it) + CDN IPs
- add a reverse proxy in front so you request only from your reverse proxy IP (require some self hosting, or using an external reverse proxy service)
else i don't think it's possible