Initial commit

.gitignore

@@ -0,0 +1 @@
+kubectl-current-context

Makefile

@@ -0,0 +1,11 @@
+.PHONY: *
+
+run:
+	@ go run main.go
+
+benchmark-go:
+	@ go build -ldflags '-s -w' -o kubectl-current-context main.go
+	@ hyperfine --warmup 3 './kubectl-current-context -o json'
+
+benchmark-kubectl:
+	@ hyperfine --warmup 3 'kubectl config current-context && kubectl config view --minify --output "jsonpath={..namespace}"'

go.mod

@@ -0,0 +1,5 @@
+module github.com/Nitive/kubectl-current-context
+
+go 1.14
+
+require gopkg.in/yaml.v2 v2.3.0

go.sum

@@ -0,0 +1,4 @@
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.3.0 h1:clyUAQHOM3G0M3f5vQj7LuJrETvjVot3Z5el9nffUtU=
+gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

main.go

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+package main
+
+import (
+	"encoding/json"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"strings"
+	"sync"
+
+	yaml "gopkg.in/yaml.v2"
+)
+
+type Context struct {
+	Context struct {
+		Namespace string `yaml:"namespace"`
+	} `yaml:"context"`
+	Name string `yaml:"name"`
+}
+
+// Kubeconfig is struct for parsing Kubeconfig file
+type Kubeconfig struct {
+	CurrentContext string    `yaml:"current-context"`
+	Contexts       []Context `yaml:"contexts"`
+}
+
+func getCurrentContext(configs []Kubeconfig) string {
+	for _, config := range configs {
+		if config.CurrentContext != "" {
+			return config.CurrentContext
+		}
+	}
+	return ""
+}
+
+func getContextNamespace(context string, configs []Kubeconfig) string {
+	for _, config := range configs {
+		for _, ctx := range config.Contexts {
+			if ctx.Name == context {
+				return ctx.Context.Namespace
+			}
+		}
+	}
+	return "default"
+}
+
+var allowedOutput = []string{"json", "slug", "context", "namespace"}
+
+func validateOutputFlag(output string) string {
+	for _, variant := range allowedOutput {
+		if output == variant {
+			return ""
+		}
+	}
+
+	return fmt.Sprintf(`Unexpected output value "%s". Allowed values: %s`, output, strings.Join(allowedOutput, ", "))
+}
+
+func main() {
+	kubeconfigRawEnv := os.Getenv("KUBECONFIG")
+	if kubeconfigRawEnv == "" {
+		fmt.Fprintln(os.Stderr, "Empty KUBECONFIG env variable")
+		os.Exit(1)
+	}
+
+	outputFlag := flag.String("o", "slug", `Output values. Either "json", "context", "namespace" or "slug" (context/namespace)`)
+	flag.Parse()
+
+	validationError := validateOutputFlag(*outputFlag)
+	if validationError != "" {
+		fmt.Println(validationError)
+		os.Exit(1)
+	}
+
+	output := *outputFlag
+
+	debugMode := os.Getenv("DEBUG") != ""
+	kubeconfigFilePaths := strings.Split(kubeconfigRawEnv, ":")
+	for i, path := range kubeconfigFilePaths {
+		kubeconfigFilePaths[i] = strings.TrimSpace(path)
+	}
+
+	parsedKubeconfigs := []Kubeconfig{}
+
+	var wg sync.WaitGroup
+	wg.Add(len(kubeconfigFilePaths))
+
+	for _, file := range kubeconfigFilePaths {
+		// Parse all files, skip files with syntax errors
+		go func(fileName string) {
+			defer wg.Done()
+
+			fileContext, err := ioutil.ReadFile(fileName)
+			if err != nil {
+				if debugMode {
+					log.Fatal(err)
+				}
+				return
+			}
+
+			var config Kubeconfig
+			err = yaml.Unmarshal(fileContext, &config)
+			if err != nil {
+				if debugMode {
+					log.Fatal(err)
+				}
+				return
+			}
+
+			parsedKubeconfigs = append(parsedKubeconfigs, config)
+		}(file)
+	}
+
+	wg.Wait()
+
+	currentContext := getCurrentContext(parsedKubeconfigs)
+
+	if output == "context" {
+		fmt.Print(currentContext)
+	}
+
+	currentNamespace := getContextNamespace(currentContext, parsedKubeconfigs)
+
+	if output == "namespace" {
+		fmt.Print(currentNamespace)
+	}
+
+	if output == "slug" {
+		fmt.Printf("%s/%s", currentContext, currentNamespace)
+	}
+
+	if output == "json" {
+		jsonOutput := struct {
+			Context   string `json:"context"`
+			Namespace string `json:"namespace"`
+		}{
+			Context:   currentContext,
+			Namespace: currentNamespace,
+		}
+
+		bytes, err := json.Marshal(&jsonOutput)
+		if err != nil {
+			fmt.Printf("Error while formatting json\n%s", err)
+			os.Exit(1)
+		}
+
+		fmt.Print(string(bytes))
+	}
+}