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.
