[4.14] bootkube.service failed in disconnected network install with imageDigestSources

When installing OCP in a disconnected network which doesn’t have access to the public registry, bootkube.service failed

from 4.14.0-0.nightly-2023-04-29-153308

Always

1.Prepare a VPC that doesn’t have the access to the Internet, setup a mirror registry inside the VPC and set related ImageContentSource in the install-config
2.Start the installation
3.

Failed when provisioning masters as it couldn’t get master ignition from bootstrap

May 04 07:31:56 maxu-az-dis-6d74v-bootstrap bootkube.sh[246724]: error: unable to read image registry.ci.openshift.org/ocp/release@sha256:227a73d8ff198a55ca0d3314d8fa94835d90769981d1c951ac741b82285f99fc: Get "https://registry.ci.openshift.org/v2/": net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
May 04 07:31:56 maxu-az-dis-6d74v-bootstrap systemd[1]: bootkube.service: Main process exited, code=exited, status=1/FAILUREMay 04 07:31:56 maxu-az-dis-6d74v-bootstrap systemd[1]: bootkube.service: Failed with result 'exit-code'.

Installation succeeded. 

In disconnected install, we’re using the ICSP to pull image from the mirror registry, but bootkube.service was still trying to access the public registry. Checked the change log of bootkube.sh.template, it seems to be a regression issue of https://github.com/openshift/installer/pull/6990, it’s using “oc adm release info -o 'jsonpath={.metadata.version}' "${RELEASE_IMAGE_DIGEST}"” to get current OCP version in this scenario.