Similar to `--no-negcache` on dnsmasq, this prevents issues which poll DNS for orchestration such as operators with StatefulSets. It can also be very confusing for users when negative caching results in a change they just made seeming to be broken until the cache expires. This assumes that 5 seconds is reasonable and will still catch repeated AAAA negative responses. We could also set the denial cache size to zero which should effectively fully disable it like dnsmasq in kube-dns but testing shows this approach seems to work well in our (albeit small) test clusters.
Currently ConfigFileAndDefaultsToInternalConfig and
FetchConfigFromFileOrCluster are used to default and load InitConfiguration
from file or cluster. These two APIs do a couple of completely separate things
depending on how they were invoked. In the case of
ConfigFileAndDefaultsToInternalConfig, an InitConfiguration could be either
defaulted with external override parameters, or loaded from file.
With FetchConfigFromFileOrCluster an InitConfiguration is either loaded from
file or from the config map in the cluster.
The two share both some functionality, but not enough code. They are also quite
difficult to use and sometimes even error prone.
To solve the issues, the following steps were taken:
- Introduce DefaultedInitConfiguration which returns defaulted version agnostic
InitConfiguration. The function takes InitConfiguration for overriding the
defaults.
- Introduce LoadInitConfigurationFromFile, which loads, converts, validates and
defaults an InitConfiguration from file.
- Introduce FetchInitConfigurationFromCluster that fetches InitConfiguration
from the config map.
- Reduce, when possible, the usage of ConfigFileAndDefaultsToInternalConfig by
replacing it with DefaultedInitConfiguration or LoadInitConfigurationFromFile
invocations.
- Replace all usages of FetchConfigFromFileOrCluster with calls to
LoadInitConfigurationFromFile or FetchInitConfigurationFromCluster.
- Delete FetchConfigFromFileOrCluster as it's no longer used.
- Rename ConfigFileAndDefaultsToInternalConfig to
LoadOrDefaultInitConfiguration in order to better describe what the function
is actually doing.
Signed-off-by: Rostislav M. Georgiev <rostislavg@vmware.com>
The rules for address parsing are:
* Explicitly specified addresses must bind successfully
* `localhost` is pinned to `127.0.0.1` and `::1` and at least one of those must bind successfully
This change also makes output of the command consistent
between runs with the same arguments.
Previously the command was using the range via map of addresses
which sometimes was producing different output because the order
of values is not guaranteed in Go.
systemd is the recommended driver as per the setup of running
the kubelet using systemd as the init system. Add a preflight
check that throws a warning if this isn't the case.
