This commit adds two new global options to kubectl: --profile and
--profile-output, writing out go profiles to disk to debug interesting and
unexpected kubectl behaviour.
As an example, here is how to capture a block file, eg. for how long are we
blocked on I/O and where?
$ kubectl get nodes --profile=mutex -v6
$ go tool pprof -png ./profile.pprof > out.png
$ google-chrome out.png
Fixes: #68679
Automatic merge from submit-queue (batch tested with PRs 67062, 67169, 67539, 67504, 66876). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Update the kubectl plugin mechanism
**Release note**:
```release-note
The plugin mechanism functionality to closely follow the git plugin design
```
Replace the existing plugin mechanism with the design proposed in https://github.com/kubernetes/community/pull/2437.
~~_The full implementation of the plugin mechanism itself is entirely contained within the first commit._~~
## Walkthrough
Under the new design, there is no plugin installation or loading required to use plugins.
A plugin is simply any executable file on a user's PATH whose name begins with `kubectl-`.
- Plugins receive the inherited environment from the `kubectl` binary. All environment variables
accessible by `kubectl` become accessible by the plugin.
- Plugins decide which command path they wish to implement based on their name. For example, a plugin wanting to provide a new command `foo`, would simply be named `kubectl-foo`.
### Creating a plugin
Below is an example plugin, that we will use for this walkthrough. Plugins may be written in any language, and handle arguments and flags in any way, optionally (as a convention) providing a way to retrieve their version via a `version` subcommand.
```bash
#!/bin/bash
# optional argument handling
if [[ "$1" == "version" ]]
then
echo "1.0.0"
exit 0
fi
# optional argument handling
if [[ "$1" == "config" ]]
then
echo $KUBECONFIG
exit 0
fi
echo "I am a plugin named kubectl-foo"
```
### Using a plugin
To use a plugin, simply make it executable:
```bash
sudo chmod +x ./kubectl-foo
```
and place it anywhere in your PATH:
```bash
sudo mv ./kubectl-foo /usr/local/bin
```
You may now invoke your plugin as a `kubectl` command:
```bash
$ kubectl foo
I am a plugin named kubectl-foo
```
All args and flags are passed as-is to the executable:
```bash
$ kubectl foo version
1.0.0
```
All environment variables are also passed as-is to the executable:
```bash
$ export KUBECONFIG=~/.kube/config
$ kubectl foo config
/home/<user>/.kube/config
$ KUBECONFIG=/etc/kube/config kubectl foo config
/etc/kube/config
```
Additionally, the first argument that is passed to a plugin will always be the full path to the location where it was invoked (`$0` would equal `/usr/local/bin/kubectl-foo` in our example above).
### Plugin discoverability
Seeing as how the `kubectl plugin` command is left as a no-op with this PR (perhaps it could serve as an entrypoint towards additional plugin functionality in the future), a small subcommand has been included that _lists all available plugin executables on a user's PATH_, along with any warnings it finds.
Example usage of this new subcommand is included below:
```bash
$ kubectl plugin list
The following kubectl-compatible plugins are available:
test/fixtures/pkg/kubectl/plugins/kubectl-foo
plugins/kubectl-foo
- warning: plugins/kubectl-foo is overshadowed by a similarly named plugin: test/fixtures/pkg/kubectl/plugins/kubectl-foo
plugins/kubectl-invalid
- warning: plugins/kubectl-invalid identified as a kubectl plugin, but it is not executable
plugins/kubectl-bar
error: 2 plugin warnings were found
```
cc @kubernetes/kubectl-maintainers @kubernetes/sig-cli-pr-reviews @soltysh @seans3 @mengqiy
Automatic merge from submit-queue (batch tested with PRs 67071, 66906, 66722, 67276, 67039). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
#50102 Task 1: Move apimachinery/pkg/watch.Until into client-go/tools/watch.UntilWithoutRetry
**What this PR does / why we need it**:
This is a split off from https://github.com/kubernetes/kubernetes/pull/50102 to go in smaller pieces.
Moves `apimachinery/pkg/watch.Until` into `client-go/tools/watch.UntilWithoutRetry` and adds context so it is cancelable.
**Release note**:
```release-note
NONE
```
**Dev release note**:
```dev-release-note
`apimachinery/pkg/watch.Until` has been moved to `client-go/tools/watch.UntilWithoutRetry`.
While switching please consider using the new `client-go/tools/watch.UntilWithSync` or `client-go/tools/watch.Until`.
```
/cc @smarterclayton @kubernetes/sig-api-machinery-pr-reviews
/milestone v1.12
/priority important-soon
/kind bug
(bug after the main PR which is this split from)
Automatic merge from submit-queue (batch tested with PRs 62901, 66562, 66938, 66927, 66926). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
snip links to internal clients
This is just an example of snipping links to the internal client from k/k. There are four more direct links to the factory method to create the internal and order of a dozen imports.
@kubernetes/sig-cli-maintainers
/assign @soltysh @juanvallejo
```release-note
NONE
```
Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Add missing error handling in schema-related code
**What this PR does / why we need it**:
Adds missing error handling to a few places.
**Which issue(s) this PR fixes**
Updates #51457. Still more work to do to fix the issue - client generation code needs to be updated (addressed in https://github.com/kubernetes/kubernetes/pull/64664).
**Release note**:
```release-note
NONE
```
/kind bug
/sig api-machinery
Automatic merge from submit-queue (batch tested with PRs 63367, 63718, 63446, 63723, 63720). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
finish new dynamic client and deprecate old dynamic client
Builds on a couple other pulls. This completes the transition to the new dynamic client.
@kubernetes/sig-api-machinery-pr-reviews
@caesarxuchao @sttts
```release-note
The old dynamic client has been replaced by a new one. The previous dynamic client will exist for one release in `client-go/deprecated-dynamic`. Switch as soon as possible.
```
Jingfang Liu