Flatten the data structure that stores features, dropping the "domain"
level from the data model. That extra level of hierarchy brought little
benefit but just caused some extra complexity, instead. The new
structure nicely matches what we have in the NodeFeatureRule object (the
matchFeatures field of uses the same flat structure with the "feature"
field having a value <domain>.<feature>, e.g. "kernel.version").
This is pre-work for introducing a new "node feature" CRD that contains
the raw feature data. It makes the life of both users and developers
easier when both CRDs, plus our internal code, handle feature data in a
similar flat structure.
Enable transmitting the discovered "raw" features over the gRPC API.
Extend pkg/api/feature with protobuf and gRPC code. In this, utilize
go-to-protobuf from k8s code-generator for auto-generating the gRPC
interface from golang code. The tool can be Installed with:
go install k8s.io/code-generator/cmd/go-to-protobuf@v0.20.7
The auto-generated code is (re-)generated/updated with "make apigen".
For auto-generating api(s).
Also, re-generate/refresh the gRPC with `make apigen` (with protoc
v3.17.3 and protoc-gen-go from github.com/golang/protobuf v1.5.2) to
sync up things.
Refactor NFD into a simple server-client system. Labeling is now done by
a separate 'nfd-master' server. It is a simple service with small
codebase, designed for easy isolation. The feature discovery part is
implemented in a 'nfd-worker' client which sends labeling requests to
nfd-server, thus, requiring no access/permissions to the Kubernetes API
itself.
Client-server communication is implemented by using gRPC. The protocol
currently consists of only one request, i.e. the labeling request.
The spec templates are converted to the new scheme. The nfd-master
server can be deployed using the nfd-master.yaml.template which now also
contains the necessary RBAC configuration. NFD workers can be deployed
by using the nfd-worker-daemonset.yaml.template or
nfd-worker-job.yaml.template (most easily used with the label-nodes.sh
script).
Only nfd-worker currently support config file or options. The (default)
NFD config file is renamed to nfd-worker.conf.
