All Kubernetes commands should show flags with hyphens in their help text even
when the flag originally was defined with underscore. Converting a command to
this style is not breaking its command line API because the old-style parameter
with underscore is accepted as alias.
The easiest solution to achieve this is to set normalization shortly before
running the command in the new central cli.Run or the few places where that
function isn't used yet.
There may be some texts which depends on normalization at flag definition time,
like the --logging-format usage warning. Those get generated assuming that
hyphens will be used.
It wasn't documented that InitLogs already uses the log flush frequency, so
some commands have called it before parsing (for example, kubectl in the
original code for logs.go). The flag never had an effect in such commands.
Fixing this turned into a major refactoring of how commands set up flags and
run their Cobra command:
- component-base/logs: implicitely registering flags during package init is an
anti-pattern that makes it impossible to use the package in commands which
want full control over their command line. Logging flags must be added
explicitly now, something that the new cli.Run does automatically.
- component-base/logs: AddFlags would have crashed in kubectl-convert if it
had been called because it relied on the global pflag.CommandLine. This
has been fixed and kubectl-convert now has the same --log-flush-frequency
flag as other commands.
- component-base/logs/testinit: an exception are tests where flag.CommandLine has
to be used. This new package can be imported to add flags to that
once per test program.
- Normalization of the klog command line flags was inconsistent. Some commands
unintentionally didn't normalize to the recommended format with hyphens. This
gets fixed for sample programs, but not for production programs because
it would be a breaking change.
This refactoring has the following user-visible effects:
- The validation error for `go run ./cmd/kube-apiserver --logging-format=json
--add-dir-header` now references `add-dir-header` instead of `add_dir_header`.
- `staging/src/k8s.io/cloud-provider/sample` uses flags with hyphen instead of
underscore.
- `--log-flush-frequency` is not listed anymore in the --logging-format flag's
`non-default formats don't honor these flags` usage text because it will also
work for non-default formats once it is needed.
- `cmd/kubelet`: the description of `--logging-format` uses hyphens instead of
underscores for the flags, which now matches what the command is using.
- `staging/src/k8s.io/component-base/logs/example/cmd`: added logging flags.
- `apiextensions-apiserver` no longer prints a useless stack trace for `main`
when command line parsing raises an error.
Because the proxy.Provider interface included
proxyconfig.EndpointsHandler, all the backends needed to
implement its methods. But iptables, ipvs, and winkernel implemented
them as no-ops, and metaproxier had an implementation that wouldn't
actually work (because it couldn't handle Services with no active
Endpoints).
Since Endpoints processing in kube-proxy is deprecated (and can't be
re-enabled unless you're using a backend that doesn't support
EndpointSlice), remove proxyconfig.EndpointsHandler from the
definition of proxy.Provider and drop all the useless implementations.
With this commit kube-proxy accepts current system values (retrieved by sysctl) which are higher than the internally known and expected values.
The code change was mistakenly created as PR in the k3s project (see https://github.com/k3s-io/k3s/pull/3505).
A real life use case is described in Rancher issue https://github.com/rancher/rancher/issues/33360.
When Kubernetes runs on a Node which itself is a container (e.g. LXC), and the value is changed on the (LXC) host, kube-proxy then fails at the next start as it does not recognize the current value and attempts to overwrite the current value with the previously known one. This result in:
```
I0624 07:38:23.053960 54 conntrack.go:103] Set sysctl 'net/netfilter/nf_conntrack_max' to 524288
F0624 07:38:23.053999 54 server.go:495] open /proc/sys/net/netfilter/nf_conntrack_max: permission denied
```
However a sysctl overwrite only makes sense if the current value is lower than the previously known and expected value. If the value was increased on the host, that shouldn't really bother kube-proxy and just go on with it.
Signed-off-by: Claudio Kuenzler ck@claudiokuenzler.com
