I enabled https for all the requests within the App Engine - Flexible Environment.
override fun configure(http: HttpSecurity) {
if (securityProperties.isRequireSsl) http.requiresChannel().anyRequest().requiresSecure()
}
But it is causing too many redirects and fails.
How to force https with Spring Boot on App Engine?
The Google Cloud Load Balancer terminates all https connections, and then forwards traffic to App Engine instances over http. Read More
Which was causing the redirects as the Spring Application was unaware of this switch.
App Engine proxies the request to the application by adding the X-Forwarded-Proto and X-Forwarded-For headers with which spring identifies the actual request protocol and where the request actually originated from.
To enable such behavior, I added the following configuration in application.yml:
server:
tomcat:
remote_ip_header: X-Forwarded-For
protocol_header: X-Forwarded-Proto