…d Installer

OKD/FCOS uses FCOS as its bootimage, i.e. when booting cluster nodes
the first time during installation. FCOS does not provide tools such
as OpenShift Client (oc) or crio.service which Agent-based Installer
uses at the rendezvous host, e.g. to launch the bootstrap control
plane.

RHCOS and SCOS include these tools, but FCOS has to pivot the root fs
[1] to okd-machine-os [2] first in order to make those tools available.

Pivoting uses 'rpm-ostree rebase' but the rendezvous host is booted
the first time the node boots from a FCOS Live ISO where the root fs
and /sysroot are mounted read-only. Thus 'rpm-ostree rebase' fails and
necessary tools will not be available, causing the setup to stall.

Until rpm-ostree has implemented support for rebasing Live ISOs [3],
this patch adapts the workaround for SNO installations [4] to also
support Agent-based Installer.

In particular, the Go conditional {{- if .BootstrapInPlace }} which
is used to mark a SNO install has been replaced with a shell if-else
which checks at runtime whether the system is launched from are on a
Live ISO.
Most code in the OpenShift ecosystem is written with RHCOS in mind
and often assumes that tools like oc or crio.service are available.
These assumptions can be satisfied by applying this workaround to all
Live ISO boots. It will not remove functionality or overwrite
configuration files in /etc and thus side effects should be minimal.

The Go conditional {{- if .BootstrapInPlace }} in the release-image-\
pivot.service has been dropped completely. This service is only used
in OKD only, so OCP will not be impacted at all. The 'Before=' option
will not cause systemd to fail if a service does not exist. So, in
case bootkube.service or kubelet.service do not exist, the option will
have no effect.
When bootkube.service or kubelet.service do exist, it must always be
ensured that release-image-pivot.service is started first because it
might reboot the system or change /usr in the Live ISO use case.
So it is safe to drop the Go conditional and ask systemd to always
launch release-image-pivot.service before bootkube.service and
kubelet.service.

[0] https://github.com/openshift/installer/blob/master/data/data/bootstrap/files/usr/local/bin/bootkube.sh.template
[1] https://github.com/openshift/installer/blob/master/data/data/bootstrap/files/usr/local/bin/bootstrap-pivot.sh.template
[2] https://github.com/openshift/okd-machine-os
[3] coreos/rpm-ostree#4547
[4] openshift#7445