Keycloak behind a Load Balancer with SSL gives a "Mixed Content" error

I have set up Keycloak (docker container) on the GCP Compute Engine (VM). After setting the sslRequired=none, I'm able to access Keycloak over a public IP (e.g. http://33.44.55.66:8080) and manage the realm.

I have configured the GCP CLassic (HTTPS) Load Balancer and added two front-ends as described below. The Load Balancer forwards the request to the Keycloak instance on the VM.

• HTTP: http://55.44.33.22/keycloak
• HTTPS: https://my-domain.com/keycloak

In the browser, the HTTP URL works fine and I'm able to login to Keycloak and manage the realm. However, for the HTTPS URL, I get the below error

Mixed Content: The page at 'https://my-domain.com/auth/admin/master/console/' was loaded over HTTPS, but requested an insecure script 'http://my-domain.com/auth/js/keycloak.js?version=gyc8p'. This request has been blocked; the content must be served over HTTPS.

Note: I tried this suggestion, but it didn't work

Can anyone help with this, please?

I would never expose Keycloak on plain http protocol. Keyclok admin console itself is secured via OIDC protocol and OIDC requires to use https protocol. So default sslRequired=EXTERNAL is safe and smart configuration option from the vendor.

SSL offloading must be configured properly:

• Keycloak container with PROXY_ADDRESS_FORWARDING=true
• loadbalancer/reverse proxy (nginx, GCP Classic Load Balancer, AWS ALB, ...) with proper request header X-Forwarded-* configuration, so Keycloak container will know correct protocol, domain which is used for the users