First of all you need to have your Google Cloud Platform service account file located in the following path:
$HOME/.gcp/osServiceAccount.json
The OpenShift installer binary will read that file if gcp is set as a platform. From the path where the knictl binary is located, and in order to pull our edge-mgmt-hub site and its requirements, please execute:
knictl fetch_requirements github.com/redhat-edge-computing/blueprint-management-hub/sites/mgmt-edge-hub.gcp.devcluster.openshift.com/
This command will download the site blueprint definition, and all its requirements (oc, openshift-install, kustomize, etc) to the $HOME/.kni/. Every site will have a separate directory within that location. The next step involves the actual rendering of the manifests (site + profile + base) into one set of manifests via kustomize that we can pass to the openshift-install binary.
knictl prepare_manifests edge-mgmt-hub.gcp.devcluster.openshift.com
If everything goes well, the command will get out some instructions to deploy the cluster. It's basically asking you to run openshift-install binary pointing to where the final manifests created by knictl are:
$HOME/.kni/edge-mgmt-hub.gcp.devcluster.openshift.com/requirements/openshift-install create cluster --dir=$HOME/.kni/edge-mgmt-hub.gcp.devcluster.openshift.com/final_manifests --log-level debug
Wait until the deployment is completed, and you will information about console endpoint, kubeadmin password and kubeconfig path.
If you have manifests that you want to deploy as Day 2 operations located in any of the 02_cluster-addons or 03_services directories, you can deploy them running the following command:
knictl apply_workloads edge-mgmt-hub.gcp.devcluster.openshift.com
This is basically running kustomize to build and render all the manifests enabling alpha plugins, and apply them via oc/kubectl.