🐛 Fallback on temp directory if user cache directory has issues

[hanlins]

The original logic is if we can get the user cache directory(i.e. os.UserCacheDir()), then create the cache directory under that user cache directory. Otherwise, create the cache directory under the temp directory.

Basically os.UserCacheDir could return a path that the current user doesn't have permission for (typically in container environment). os.UserCacheDir typically returns the $HOME. If $HOME is set but the user doesn't have permission to create directories in $HOME, it will panic. This is somewhat confusing since it could also fallback on the temp directory.

The update logic will simply attempt to create directory under os.UserCacheDir(). If os.UserCacheDir returns error or user encounters error creating directories under it, it will fallback onto temp directory and retry.

Here's the manual verification:

➜  test cat main.go
package main

import (
	"fmt"
	"os"
	"path/filepath"
)

func main() {
	const (
		eventTestDir = "kubebuilder-envtest"
		permission   = 0750
	)
	if baseDir, err := os.UserCacheDir(); err == nil {
		cacheDir := filepath.Join(baseDir, eventTestDir)
		fmt.Println("#1", cacheDir)
		if err := os.MkdirAll(cacheDir, permission); err == nil {
			return
		}
	}
	cacheDir := filepath.Join(os.TempDir(), eventTestDir)
	fmt.Println("#2", cacheDir)
	if err := os.MkdirAll(cacheDir, permission); err != nil {
		panic(err)
	}

}
➜  test GO111MODULE=off go build .
➜  test # if HOME directory doesn't have permission issue
➜  test HOME=$(pwd)/somepath ./test
#1 /home/ubuntu/test/somepath/.cache/kubebuilder-envtest
➜  test # if HOME directory has permission issue
➜  test rm -rf somepath/.cache
➜  test sudo chown root:root somepath
➜  test HOME=$(pwd)/somepath ./test
#1 /home/ubuntu/test/somepath/.cache/kubebuilder-envtest
#2 /tmp/kubebuilder-envtest

Fixes #1845

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[hanlins]

/test pull-controller-runtime-test-master

[hanlins]

/assign controller-runtime-maintainers

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[hanlins]

/assign @vincepri

[vincepri]

@hanlins There is already a PR out for this issue, see #1800

[alvaroaleman]

This was fixed in #1800