Move the previously-protobuf-only internal "feature api" over to the
public "nfd api" package. This is in preparation for introducing a new
CRD API for communicating features.
This patch carries no functional changes. Just moving code around.
This patch changes a rare corner case of custom label rules with an
empty set of matchexpressions. The patch removes a special case where an
empty match expression set matched everything and returned all feature
elements for templates to consume. With this patch the match expression
set logically evaluates all expressions in the set and returns all
matches - if there are no expressions there are no matches and no
matched features are returned. However, the overall match result
(determining if "non-template" labels will be created) in this special
case will be "true" as before as none of the zero match expressions
failed.
The former behavior was somewhat illogical and counterintuitive: having
1 to N expressions matched and returned 1 to N features (at most), but,
having 0 expressions always matched everything and returned all
features. This was some leftover proof-of-concept functionality (for
some possible future extensions) that should have been removed before
merging.
Support templating of label names in feature rules. It is available both
in NodeFeatureRule CRs and in custom rule configuration of nfd-worker.
This patch adds a new 'labelsTemplate' field to the rule spec, making it
possible to dynamically generate multiple labels per rule based on the
matched features. The feature relies on the golang "text/template"
package. When expanded, the template must contain labels in a raw
<key>[=<value>] format (where 'value' defaults to "true"), separated by
newlines i.e.:
- name: <rule-name>
labelsTemplate: |
<label-1>[=<value-1>]
<label-2>[=<value-2>]
...
All the matched features of 'matchFeatures' directives are available for
templating engine in a nested data structure that can be described in
yaml as:
.
<domain-1>:
<key-feature-1>:
- Name: <matched-key>
- ...
<value-feature-1:
- Name: <matched-key>
Value: <matched-value>
- ...
<instance-feature-1>:
- <attribute-1-name>: <attribute-1-value>
<attribute-2-name>: <attribute-2-value>
...
- ...
<domain-2>:
...
That is, the per-feature data available for matching depends on the type
of feature that was matched:
- "key features": only 'Name' is available
- "value features": 'Name' and 'Value' can be used
- "instance features": all attributes of the matched instance are
available
NOTE: In case of matchAny is specified, the template is executed
separately against each individual matchFeatures matcher and the
eventual set of labels is a superset of all these expansions. Consider
the following:
- name: <name>
labelsTemplate: <template>
matchAny:
- matchFeatures: <matcher#1>
- matchFeatures: <matcher#2>
matchFeatures: <matcher#3>
In the example above (assuming the overall result is a match) the
template would be executed on matcher#1 and/or matcher#2 (depending on
whether both or only one of them match), and finally on matcher#3, and
all the labels from these separate expansions would be created (i.e. the
end result would be a union of all the individual expansions).
NOTE 2: The 'labels' field has priority over 'labelsTemplate', i.e.
labels specified in the 'labels' field will override any labels
originating from the 'labelsTemplate' field.
A special case of an empty match expression set matches everything (i.e.
matches/returns all existing keys/values). This makes it simpler to
write templates that run over all values. Also, makes it possible to
later implement support for templates that run over all _keys_ of a
feature.
Some example configurations:
- name: "my-pci-template-features"
labelsTemplate: |
{{ range .pci.device }}intel-{{ .class }}-{{ .device }}=present
{{ end }}
matchFeatures:
- feature: pci.device
matchExpressions:
class: {op: InRegexp, value: ["^06"]}
vendor: ["8086"]
- name: "my-system-template-features"
labelsTemplate: |
{{ range .system.osrelease }}system-{{ .Name }}={{ .Value }}
{{ end }}
matchFeatures:
- feature: system.osRelease
matchExpressions:
ID: {op: Exists}
VERSION_ID.major: {op: Exists}
Imaginative template pipelines are possible, of course, but care must be
taken in order to produce understandable and maintainable rule sets.
Create a new package pkg/apis/nfd/v1alpha1 and migrate the custom rule
expressions over there. This is the first step in creating a new CRD API
for custom rules.
