The RendezvousIP value is not substituted in the rendezvous host environment file. The field NODE_ZERO_IP={{.RendezvousIP}} in etc/assisted/rendezvous-host.env remains unresolved, leading to invalid API requests (http://{{.RendezvousIP}}:8090/...). As a result, the assisted service container fails to start, the Assisted Installer UI keeps on waiting for the UI to come up which never comes up and process times out. This leads to cluster installation failure.

    4.21 OVE

    Always

    1. Build OVE ISO with registry.ci.openshift.org/ocp/release:4.21.0-0.ci-2025-09-17-021925 or any other 4.21 release image
    2. Install a cluster
    
    

    Cluster installation fails. The process keeps waiting forever and show 
 
Assisted install UI not ready, retrying in 30 seconds...
+(./agent/06_agent_create_cluster.sh:255): check_assisted_install_UI(): sleep 30
+(./agent/06_agent_create_cluster.sh:249): check_assisted_install_UI(): true
+(./agent/06_agent_create_cluster.sh:250): check_assisted_install_UI(): curl -s -o /dev/null -w '%{http_code}' http://192.168.111.22:3001
+(./agent/06_agent_create_cluster.sh:250): check_assisted_install_UI(): grep -q '^200$'
+(./agent/06_agent_create_cluster.sh:254): check_assisted_install_UI(): echo 'Assisted install UI not ready, retrying in 30 seconds...'
Assisted install UI not ready, retrying in 30 seconds...
+(./agent/06_agent_create_cluster.sh:255): check_assisted_install_UI(): sleep 30
+(./agent/06_agent_create_cluster.sh:249): check_assisted_install_UI(): true
+(./agent/06_agent_create_cluster.sh:250): check_assisted_install_UI(): curl -s -o /dev/null -w '%{http_code}' http://192.168.111.22:3001
+(./agent/06_agent_create_cluster.sh:250): check_assisted_install_UI(): grep -q '^200$'
+(./agent/06_agent_create_cluster.sh:254): check_assisted_install_UI(): echo 'Assisted install UI not ready, retrying in 30 seconds...' 



In agent gather logs, you see 

Sep 17 22:19:36 master-2 start-agent.sh[2975]: Querying assisted-service for infra-env-id...Sep 17 22:19:36 master-2 start-agent.sh[2995]: curl: (3) nested brace in URL position 9:Sep 17 22:19:36 master-2 start-agent.sh[2995]: http://{{.RendezvousIP}}:8090/api/assisted-install/v2/infra-envs

    The RendezvousIP should be resolved correctly. Cluster installation should succeed and UI should be available.