Separate feature discovery and creation of feature labels in the system
source.
Also, change the implementation of the nodeName custom rule to utilize
the FeatureSource interface of the system source.
Also, add minimalist unit test.
Specify a new interface for managing "raw" feature data. This is the
first step to separate raw feature data from node labels. None of the
feature sources implement this interface, yet.
This patch unifies the data format of "raw" features by dividing them
into three different basic types.
- keys, a set of names without any associated values, e.g. CPUID flags
or loaded kernel modules
- values, a map of key-value pairs, for features with a single value,
e.g. kernel config flags or os version
- instances, a list of instances each of which has multiple attributes
(key-value pairs of their own), e.g. PCI or USB devices
The new feature data types are defined in a new "pkg/api/feature"
package, catering decoupling and re-usability of code e.g. within future
extentions of the NFD gRPC API.
Rename the Discover() method of LabelSource interface to GetLabels().
Implement new registration infrastructure under the "source" package.
This change loosens the coupling between label sources and the
nfd-worker, making it easier to refactor and move the code around.
Also, create a separate interface (ConfigurableSource) for configurable
feature sources in order to eliminate boilerplate code.
Add safety checks to the sources that they actually implement the
interfaces they should.
In sake of consistency and predictability (of behavior) change all
methods of the sources to use pointer receivers.
Add simple unit tests for the new functionality and include source/...
into make test target.
Extend the FeatureSource interface with new methods for configuration
handling. This enables easier on-the fly reconfiguration of the
feature sources. Further, it simplifies adding config support to feature
sources in the future. Stub methods are added to sources that do not
currently have any configurability.
The patch fixes some (corner) cases with the overrides (--options)
handling, too:
- Overrides were not applied if config file was missing or its parsing
failed
- Overrides for a certain source did not have effect if an empty config
for the source was specified in the config file. This was caused by
the first pass of parsing (config file) setting a nil pointer to the
source-specific config, effectively detaching it from the main config.
The second pass would then create a new instance of the source
specific config, but, this was not visible in the feature source, of
course.
Add two new attributes 'VERSION_ID.major' and 'VERSION_ID.minor' to the
os_release feature. These represent the first two components of
the OS version (version components are assumed to be separated by a
dot). E.g. if VERSION_ID would be 1.2.rc3 major and minor versions would
be 1 and 2, respectively:
feature.node.kubernetes.io/system-os_release.VERSION_ID=1.2.rc3
feature.node.kubernetes.io/system-os_release.VERSION_ID.major=1
feature.node.kubernetes.io/system-os_release.VERSION_ID.minor=2
The version components must be purely numerical in order for them to be
advertised. This way they can be fully (and reliably) utilized in
nodeAffinity, including relative (Gt and Lt) operators.
Implement new 'system' feature source. It now detects OS release
information from the os-release file, assumed to be available at
/host-etc/os-release. It currently creates two labels (assuming that the
corresponding fields are found in the os-release file), with example
values:
feature.node.kubernetes.io/system-os_release.ID=opensuse
feature.node.kubernetes.io/system-os_release.VERSION_ID=42.3
Also, update the template spec to mount /etc/os-release file from the
host inside the container.
