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.
Move the rule processing of matchFeatures and matchAny from
source/custom package over to pkg/apis/nfd, aiming for better integrity
and re-usability of the code. Does not change the CRD API as such, just
adds more supportive functions.
2021-11-17 14:02:00 +02:00
Renamed from source/custom/custom_test.go (Browse further)
