Fail early on incorrect version of k8s

Makefile

@@ -5,7 +5,7 @@ RELEASE_VERSION ?= latest
 .PHONY: local-test local-build local-build-static docker-test docker-build docker-build-static build-bats docker-acceptance release update-deps build-single-target
 
 local-test:
-	go test -race ./...
+	go test -race ./... -count=1
 
 local-build:
 	git config --global --add safe.directory $$PWD

acceptance.bats

@@ -180,6 +180,13 @@ resetCacheFolder() {
   [ "$status" -eq 1 ]
 }
 
+@test "Fail early when passing a non valid -kubernetes-version" {
+  run bin/kubeconform -kubernetes-version 1.25 fixtures/valid.yaml
+  [[ "$output" == "invalid value "1.25" for flag -kubernetes-version: 1.25 is not a valid version. Valid values are 'master' (default) or full version x.y.z (e.g. '1.27.2')"* ]]
+  [[ `echo "$output" | wc -l` -eq 1 ]]
+  [ "$status" -eq 1 ]
+}
+
 @test "Pass with a valid input when validating against openshift manifests" {
   run bin/kubeconform -kubernetes-version 3.8.0  -schema-location 'https://raw.githubusercontent.com/garethr/openshift-json-schema/master/{{ .NormalizedKubernetesVersion }}-standalone{{ .StrictSuffix }}/{{ .ResourceKind }}.json'  -summary fixtures/valid.yaml
   [ "$status" -eq 0 ]

cmd/kubeconform/main.go

@@ -84,7 +84,7 @@ func kubeconform(cfg config.Config) int {
 		SkipTLS:              cfg.SkipTLS,
 		SkipKinds:            cfg.SkipKinds,
 		RejectKinds:          cfg.RejectKinds,
-		KubernetesVersion:    cfg.KubernetesVersion,
+		KubernetesVersion:    cfg.KubernetesVersion.String(),
 		Strict:               cfg.Strict,
 		IgnoreMissingSchemas: cfg.IgnoreMissingSchemas,
 	})

pkg/config/config.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"flag"
 	"fmt"
+	"regexp"
 	"strings"
 )
 
@@ -15,7 +16,7 @@ type Config struct {
 	Help                   bool                `yaml:"help" json:"help"`
 	IgnoreFilenamePatterns []string            `yaml:"ignoreFilenamePatterns" json:"ignoreFilenamePatterns"`
 	IgnoreMissingSchemas   bool                `yaml:"ignoreMissingSchemas" json:"ignoreMissingSchemas"`
-	KubernetesVersion      string              `yaml:"kubernetesVersion" json:"kubernetesVersion"`
+	KubernetesVersion      k8sVersionValue     `yaml:"kubernetesVersion" json:"kubernetesVersion"`
 	NumberOfWorkers        int                 `yaml:"numberOfWorkers" json:"numberOfWorkers"`
 	OutputFormat           string              `yaml:"output" json:"output"`
 	RejectKinds            map[string]struct{} `yaml:"reject" json:"reject"`
@@ -39,6 +40,24 @@ func (ap *arrayParam) Set(value string) error {
 	return nil
 }
 
+type k8sVersionValue string
+
+func (kv *k8sVersionValue) String() string {
+	return string(*kv)
+}
+
+func (kv k8sVersionValue) MarshalText() ([]byte, error) {
+	return []byte(kv), nil
+}
+
+func (kv *k8sVersionValue) UnmarshalText(v []byte) error {
+	if ok, _ := regexp.MatchString(`^(master|\d+\.\d+\.\d+)$`, string(v)); ok != true {
+		return fmt.Errorf("%v is not a valid version. Valid values are 'master' (default) or full version x.y.z (e.g. '1.27.2')", kv.String())
+	}
+	*kv = k8sVersionValue(v)
+	return nil
+}
+
 func splitCSV(csvStr string) map[string]struct{} {
 	splitValues := strings.Split(csvStr, ",")
 	valuesMap := map[string]struct{}{}
@@ -63,7 +82,7 @@ func FromFlags(progName string, args []string) (Config, string, error) {
 	c := Config{}
 	c.Files = []string{}
 
-	flags.StringVar(&c.KubernetesVersion, "kubernetes-version", "master", "version of Kubernetes to validate against, e.g.: 1.18.0")
+	flags.TextVar(&c.KubernetesVersion, "kubernetes-version", k8sVersionValue("master"), "version of Kubernetes to validate against, e.g.: 1.18.0")
 	flags.Var(&schemaLocationsParam, "schema-location", "override schemas location search path (can be specified multiple times)")
 	flags.StringVar(&skipKindsCSV, "skip", "", "comma-separated list of kinds or GVKs to ignore")
 	flags.StringVar(&rejectKindsCSV, "reject", "", "comma-separated list of kinds or GVKs to reject")