Add support for passing manifests via stdin

Readme.md

@@ -101,6 +101,12 @@ $ echo $?
 1
 ```
 
+* Passing manifests via Stdin
+```
+cat fixtures/valid.yaml  | ./bin/kubeconform -summary -
+Summary: 1 resource found parsing stdin - Valid: 1, Invalid: 0, Errors: 0 Skipped: 0
+```
+
 * Validating a folder, increasing the number of parallel workers
 ```
 $ ./bin/kubeconform -summary -n 16 fixtures

acceptance.bats

@@ -125,3 +125,20 @@
   run bin/kubeconform -kubernetes-version 3.8.0  -schema-location 'https://raw.githubusercontent.com/garethr/openshift-json-schema/master/{{ .NormalizedVersion }}-standalone{{ .StrictSuffix }}/{{ .ResourceKind }}.json'  -summary fixtures/invalid.yaml
   [ "$status" -eq 1 ]
 }
+
+@test "Pass when parsing a valid Kubernetes config YAML file on stdin" {
+  run bash -c "cat fixtures/valid.yaml | bin/kubeconform -summary"
+  [ "$status" -eq 0 ]
+  [ "$output" = "Summary: 1 resource found parsing stdin - Valid: 1, Invalid: 0, Errors: 0 Skipped: 0" ]
+}
+
+@test "Pass when parsing a valid Kubernetes config YAML file explicitly on stdin" {
+  run bash -c "cat fixtures/valid.yaml | bin/kubeconform -summary"
+  [ "$status" -eq 0 ]
+  [ "$output" = "Summary: 1 resource found parsing stdin - Valid: 1, Invalid: 0, Errors: 0 Skipped: 0" ]
+}
+
+@test "Fail when parsing an invalid Kubernetes config file on stdin" {
+   run bash -c "cat fixtures/invalid.yaml | bin/kubeconform -"
+   [ "$status" -eq 1 ]
+ }

cmd/kubeconform/main.go

@@ -4,14 +4,13 @@ import (
 	"bytes"
 	"flag"
 	"fmt"
+	"github.com/xeipuuv/gojsonschema"
 	"io"
 	"io/ioutil"
 	"os"
 	"strings"
 	"sync"
 
-	"github.com/xeipuuv/gojsonschema"
-
 	"github.com/yannh/kubeconform/pkg/cache"
 	"github.com/yannh/kubeconform/pkg/fsutils"
 	"github.com/yannh/kubeconform/pkg/output"
@@ -136,14 +135,14 @@ func (ap *arrayParam) Set(value string) error {
 	return nil
 }
 
-func getLogger(outputFormat string, printSummary, verbose bool) (output.Output, error) {
+func getLogger(outputFormat string, printSummary, isStdin, verbose bool) (output.Output, error) {
 	w := os.Stdout
 
 	switch {
 	case outputFormat == "text":
-		return output.Text(w, printSummary, verbose), nil
+		return output.Text(w, printSummary, isStdin, verbose), nil
 	case outputFormat == "json":
-		return output.JSON(w, printSummary, verbose), nil
+		return output.JSON(w, printSummary, isStdin, verbose), nil
 	default:
 		return nil, fmt.Errorf("-output must be text or json")
 	}
@@ -244,10 +243,18 @@ func realMain() int {
 		return 1
 	}
 
+	// Detect whether we have data being piped through stdin
+	stat, _ := os.Stdin.Stat()
+	isStdin := (stat.Mode() & os.ModeCharDevice) == 0
+
 	skipKinds := skipKindsMap(skipKindsCSV)
 
-	for _, file := range flag.Args() {
+	if len(flag.Args()) == 1 && flag.Args()[0] == "-" {
-		files = append(files, file)
+		isStdin = true
+	} else {
+		for _, file := range flag.Args() {
+			files = append(files, file)
+		}
 	}
 
 	filter := func(signature resource.Signature) bool {
@@ -273,6 +280,7 @@ func realMain() int {
 	}
 
 	validationResults := make(chan []validationResult)
+	c := cache.New()
 
 	fileBatches := make(chan []string)
 	go func() {
@@ -281,7 +289,7 @@ func realMain() int {
 	}()
 
 	var o output.Output
-	if o, err = getLogger(outputFormat, summary, verbose); err != nil {
+	if o, err = getLogger(outputFormat, summary, isStdin, verbose); err != nil {
 		fmt.Fprintln(os.Stderr, err)
 		return 1
 	}
@@ -289,38 +297,46 @@ func realMain() int {
 	res := make(chan bool)
 	go processResults(o, validationResults, res)
 
-	c := cache.New()
+	if isStdin {
-	var wg sync.WaitGroup
+		res := ValidateStream(os.Stdin, registries, k8sVersion, c, filter, ignoreMissingSchemas)
-	for i := 0; i < nWorkers; i++ {
+		for i := range res {
-		wg.Add(1)
+			res[i].filename = "stdin"
-		go func() {
+		}
-			defer wg.Done()
+		validationResults <- res
+	} else {
+		var wg sync.WaitGroup
+		for i := 0; i < nWorkers; i++ {
+			wg.Add(1)
+			go func() {
+				defer wg.Done()
 
-			for fileBatch := range fileBatches {
+				for fileBatch := range fileBatches {
-				for _, filename := range fileBatch {
+					for _, filename := range fileBatch {
-					f, err := os.Open(filename)
+						f, err := os.Open(filename)
-					if err != nil {
+						if err != nil {
-						validationResults <- []validationResult{{
+							validationResults <- []validationResult{{
-							filename: filename,
+								filename: filename,
-							err:      err,
+								err:      err,
-							skipped:  true,
+								skipped:  true,
-						}}
+							}}
-						continue
+							continue
+						}
+
+						res := ValidateStream(f, registries, k8sVersion, c, filter, ignoreMissingSchemas)
+						f.Close()
+
+						for i := range res {
+							res[i].filename = filename
+						}
+						validationResults <- res
 					}
-
-					res := ValidateStream(f, registries, k8sVersion, c, filter, ignoreMissingSchemas)
-					f.Close()
-
-					for i := range res {
-						res[i].filename = filename
-					}
-					validationResults <- res
 				}
-			}
+			}()
-		}()
+		}
+
+		wg.Wait()
 	}
 
-	wg.Wait()
 	close(validationResults)
 	success := <-res
 	o.Flush()

pkg/output/json.go

@@ -24,7 +24,7 @@ type jsono struct {
 }
 
 // JSON will output the results of the validation as a JSON
-func JSON(w io.Writer, withSummary bool, verbose bool) Output {
+func JSON(w io.Writer, withSummary bool, isStdin, verbose bool) Output {
 	return &jsono{
 		w:           w,
 		withSummary: withSummary,

pkg/output/json_test.go

@@ -100,7 +100,7 @@ func TestJSONWrite(t *testing.T) {
 		},
 	} {
 		w := new(bytes.Buffer)
-		o := JSON(w, testCase.withSummary, testCase.verbose)
+		o := JSON(w, testCase.withSummary, false, testCase.verbose)
 
 		for _, res := range testCase.res {
 			o.Write(res.fileName, res.kind, res.name, res.version, res.err, res.skipped)

pkg/output/text.go

@@ -10,16 +10,18 @@ type text struct {
 	sync.Mutex
 	w                                   io.Writer
 	withSummary                         bool
+	isStdin                             bool
 	verbose                             bool
 	files                               map[string]bool
 	nValid, nInvalid, nErrors, nSkipped int
 }
 
 // Text will output the results of the validation as a text
-func Text(w io.Writer, withSummary, verbose bool) Output {
+func Text(w io.Writer, withSummary, isStdin, verbose bool) Output {
 	return &text{
 		w:           w,
 		withSummary: withSummary,
+		isStdin:     isStdin,
 		verbose:     verbose,
 		files:       map[string]bool{},
 		nValid:      0,
@@ -76,7 +78,11 @@ func (o *text) Flush() error {
 		if nFiles > 1 {
 			filesPlural = "s"
 		}
-		_, err = fmt.Fprintf(o.w, "Summary: %d resource%s found in %d file%s - Valid: %d, Invalid: %d, Errors: %d Skipped: %d\n", nResources, resourcesPlural, nFiles, filesPlural, o.nValid, o.nInvalid, o.nErrors, o.nSkipped)
+		if o.isStdin {
+			_, err = fmt.Fprintf(o.w, "Summary: %d resource%s found parsing stdin - Valid: %d, Invalid: %d, Errors: %d Skipped: %d\n", nResources, resourcesPlural, o.nValid, o.nInvalid, o.nErrors, o.nSkipped)
+		} else {
+			_, err = fmt.Fprintf(o.w, "Summary: %d resource%s found in %d file%s - Valid: %d, Invalid: %d, Errors: %d Skipped: %d\n", nResources, resourcesPlural, nFiles, filesPlural, o.nValid, o.nInvalid, o.nErrors, o.nSkipped)
+		}
 	}
 
 	return err

pkg/output/text_test.go

@@ -72,7 +72,7 @@ Summary: 1 resource found in 1 file - Valid: 1, Invalid: 0, Errors: 0 Skipped: 0
 		},
 	} {
 		w := new(bytes.Buffer)
-		o := Text(w, testCase.withSummary, testCase.verbose)
+		o := Text(w, testCase.withSummary, false, testCase.verbose)
 
 		for _, res := range testCase.res {
 			o.Write(res.fileName, res.kind, res.name, res.version, res.err, res.skipped)