Merge pull request #52753 from munnerz/sample-controller

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>.

sample-controller: add example CRD controller

**What this PR does / why we need it**:

Adds a sample-controller example repository

fixes #52752

**Special notes for your reviewer**:

This is currently based on the sttts:sttts-codegen-scripts branch and should not be merged until that is (ref https://github.com/kubernetes/kubernetes/pull/52186)

**Release note**:

```
Add sample-controller repository
```

/cc @sttts @nikhita @colemickens

Kubernetes-commit: 9a7800f7d2efb88b397674672ac56f898826cf7c

vendor/github.com/googleapis/gnostic/compiler/reader.go

@@ -0,0 +1,167 @@
+// Copyright 2017 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package compiler
+
+import (
+	"fmt"
+	"gopkg.in/yaml.v2"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"net/url"
+	"path/filepath"
+	"strings"
+)
+
+var fileCache map[string][]byte
+var infoCache map[string]interface{}
+var count int64
+
+var verboseReader = false
+
+func initializeFileCache() {
+	if fileCache == nil {
+		fileCache = make(map[string][]byte, 0)
+	}
+}
+
+func initializeInfoCache() {
+	if infoCache == nil {
+		infoCache = make(map[string]interface{}, 0)
+	}
+}
+
+// FetchFile gets a specified file from the local filesystem or a remote location.
+func FetchFile(fileurl string) ([]byte, error) {
+	initializeFileCache()
+	bytes, ok := fileCache[fileurl]
+	if ok {
+		if verboseReader {
+			log.Printf("Cache hit %s", fileurl)
+		}
+		return bytes, nil
+	}
+	log.Printf("Fetching %s", fileurl)
+	response, err := http.Get(fileurl)
+	if err != nil {
+		return nil, err
+	}
+	defer response.Body.Close()
+	bytes, err = ioutil.ReadAll(response.Body)
+	if err == nil {
+		fileCache[fileurl] = bytes
+	}
+	return bytes, err
+}
+
+// ReadBytesForFile reads the bytes of a file.
+func ReadBytesForFile(filename string) ([]byte, error) {
+	// is the filename a url?
+	fileurl, _ := url.Parse(filename)
+	if fileurl.Scheme != "" {
+		// yes, fetch it
+		bytes, err := FetchFile(filename)
+		if err != nil {
+			return nil, err
+		}
+		return bytes, nil
+	}
+	// no, it's a local filename
+	bytes, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return nil, err
+	}
+	return bytes, nil
+}
+
+// ReadInfoFromBytes unmarshals a file as a yaml.MapSlice.
+func ReadInfoFromBytes(filename string, bytes []byte) (interface{}, error) {
+	initializeInfoCache()
+	cachedInfo, ok := infoCache[filename]
+	if ok {
+		if verboseReader {
+			log.Printf("Cache hit info for file %s", filename)
+		}
+		return cachedInfo, nil
+	}
+	if verboseReader {
+		log.Printf("Reading info for file %s", filename)
+	}
+	var info yaml.MapSlice
+	err := yaml.Unmarshal(bytes, &info)
+	if err != nil {
+		return nil, err
+	}
+	infoCache[filename] = info
+	return info, nil
+}
+
+// ReadInfoForRef reads a file and return the fragment needed to resolve a $ref.
+func ReadInfoForRef(basefile string, ref string) (interface{}, error) {
+	initializeInfoCache()
+	{
+		info, ok := infoCache[ref]
+		if ok {
+			if verboseReader {
+				log.Printf("Cache hit for ref %s#%s", basefile, ref)
+			}
+			return info, nil
+		}
+	}
+	if verboseReader {
+		log.Printf("Reading info for ref %s#%s", basefile, ref)
+	}
+	count = count + 1
+	basedir, _ := filepath.Split(basefile)
+	parts := strings.Split(ref, "#")
+	var filename string
+	if parts[0] != "" {
+		filename = basedir + parts[0]
+	} else {
+		filename = basefile
+	}
+	bytes, err := ReadBytesForFile(filename)
+	if err != nil {
+		return nil, err
+	}
+	info, err := ReadInfoFromBytes(filename, bytes)
+	if err != nil {
+		log.Printf("File error: %v\n", err)
+	} else {
+		if len(parts) > 1 {
+			path := strings.Split(parts[1], "/")
+			for i, key := range path {
+				if i > 0 {
+					m, ok := info.(yaml.MapSlice)
+					if ok {
+						found := false
+						for _, section := range m {
+							if section.Key == key {
+								info = section.Value
+								found = true
+							}
+						}
+						if !found {
+							infoCache[ref] = nil
+							return nil, NewError(nil, fmt.Sprintf("could not resolve %s", ref))
+						}
+					}
+				}
+			}
+		}
+	}
+	infoCache[ref] = info
+	return info, nil
+}