ubuntu,centos,debian: get_linux_distro to align with platform.dist
A recent commit added get_linux_distro to replace the deprecated python
platform.dist module behavior before it is dropped from python. It added
behavior that was compliant on OpenSuSE and SLES, by returning
(<distro_name>, <distro_version>, <cpu-arch>).
Fix get_linux_distro to behave more like the specific distribution's
platform.dist on ubuntu, centos and debian, which will return the
distribution release codename as the third element instead of <cpu-arch>.
SLES and OpenSUSE will retain their current behavior.
update_metadata: a datasource can support network re-config every boot
Very basic type definitions are now defined to distinguish 'boot'
events from 'new instance (first boot)'. Event types will now be handed
to a datasource.update_metadata method which can determine whether
to refresh its metadata and re-render configuration based on that
source event.
A datasource can 'subscribe' to an event by setting up the update_events
attribute on the datasource class which describe what config scope is
updated by a list of matching events. By default datasources will have
the following update_events: {'network': [EventType.BOOT_NEW_INSTANCE]}
This setting says the datasource will re-write network configuration only
on first boot of a new instance or when the instance id changes.
New methods are now present on the datasource:
- clear_cached_attrs: Resets cached datasource attributes to values
listed in datasource.cached_attr_defaults. This is performed prior to
processing a fresh metadata process to avoid keeping old/invalid
cached data around.
- update_metadata: accepts source_event_types to determine if the
metadata should be crawled again and processed
The salt minion integration test as we had it did not do a whole lot
more than the unit tests on that module did. Additionally, it caused
some transient failures at least in Ubuntu 18.04.
At a future date we may choose to add an integration test that installs
salt-minion and salt server and configures it to be a better test.
When cloud-init tries to read a key from a keyserver, it will now
retry twice with 1 second in between each.
Retries of import are done by default because keyservers can be
unreliable. Additionally, there is no way to determine the difference
between a non-existant key and a failure. In both cases gpg (at least
2.2.4) exits with status 2 and stderr: "keyserver receive failed: No data"
It is assumed that a key provided to cloud-init exists on the keyserver so
re-trying makes better sense than failing.
There is also a change here from 'gpg --recv' to the longer
'gpg --recv-keys'. That option is functional and working back to
centos 6 (gpg 2.0.14) and ubuntu 14.04 (gpg 1.4.16).
