Stdin support (#30)

README.md

@@ -31,6 +31,11 @@ Sort manifests contained the manifest file that is specified.
 $ ksort -f ./app.yaml
 ```
 
+Sort manifests passed into stdin.
+```
+$ cat app.yaml | ksort -f-
+```
+
 ## Installation
 
 You can download an archive file from [GitHub Releases](https://github.com/superbrothers/ksort/releases), then extract it and install a binary.

ksort.go

@@ -8,6 +8,7 @@ file that was distributed with this source code.
 package ksort
 
 import (
+	"bufio"
 	"errors"
 	"flag"
 	"fmt"
@@ -40,9 +41,12 @@ using SortByKind function in Kubernetes Helm.`
 
   # Sort manifests contained the manifest file.
   ksort -f app.yaml
-  
+
   # Sort manifests in uninstall order.
-  ksort -f ./manifests --delete`
+  ksort -f ./manifests --delete
+
+  # Sort manifests passed into stdin.
+  cat app.yaml | ksort -f -`
 
 	kindUnknown = "Unknown"
 )
@@ -132,6 +136,18 @@ func (o *options) run() error {
 	contents := map[string]string{}
 
 	for _, filename := range o.filenameOptions.Filenames {
+		if filename == "-" {
+			klog.V(2).Infof("Reading manifest from the standard input")
+
+			var lines []string
+			scanner := bufio.NewScanner(o.In)
+			for scanner.Scan() {
+				lines = append(lines, scanner.Text())
+			}
+			contents[""] = strings.Join(lines, "\n")
+			continue
+		}
+
 		klog.V(2).Infof("Walking the file tree rooted at %q", filename)
 
 		err := filepath.Walk(filename, func(path string, info os.FileInfo, err error) error {
@@ -202,7 +218,10 @@ func (o *options) run() error {
 			i = len(manifests) - (i + 1)
 		}
 
-		a[i] += fmt.Sprintf("# Source: %s\n", m.Name)
+		// If manifest data is read from stdin, m.Name is empty
+		if m.Name != "" {
+			a[i] += fmt.Sprintf("# Source: %s\n", m.Name)
+		}
 
 		if m.Head.Kind == kindUnknown {
 			a[i] += "# WARNING: It looks like that this file is not a manifest file\n"

ksort_test.go

@@ -24,10 +24,12 @@ func TestPrintVersionInformation(t *testing.T) {
 func TestCommand(t *testing.T) {
 	tests := []struct {
 		args []string
+		in   string
 		out  string
 	}{
 		{
 			args: []string{"--filename", "testdata/rbac.yaml"},
+			in:   "",
 			out: `# Source: testdata/rbac.yaml
 apiVersion: rbac.authorization.k8s.io/v1
 kind: ClusterRole
@@ -55,6 +57,7 @@ metadata:
 		},
 		{
 			args: []string{"--filename", "testdata"},
+			in:   "",
 			out: `# Source: testdata/configmap.yaml
 apiVersion: v1
 kind: ConfigMap
@@ -94,6 +97,7 @@ metadata:
 		},
 		{
 			args: []string{"--filename", "testdata/deployment.yaml", "--filename", "testdata/rbac.yaml"},
+			in:   "",
 			out: `# Source: testdata/rbac.yaml
 apiVersion: rbac.authorization.k8s.io/v1
 kind: ClusterRole
@@ -160,6 +164,7 @@ metadata:
 		},
 		{
 			args: []string{"--recursive", "--filename", "testdata"},
+			in:   "",
 			out: `# Source: testdata/test-recursive/ns.yaml
 apiVersion: v1
 kind: Namespace
@@ -201,12 +206,36 @@ apiVersion: apps/v1
 kind: Deployment
 metadata:
   name: deployment
+`,
+		},
+		{
+			args: []string{"--filename", "-"},
+			in: `apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRoleBinding
+metadata:
+  name: ClusterRoleBinding
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRole
+metadata:
+  name: ClusterRole
+`,
+			out: `apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRole
+metadata:
+  name: ClusterRole
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRoleBinding
+metadata:
+  name: ClusterRoleBinding
 `,
 		},
 	}
 
 	for i, tt := range tests {
-		streams, _, out, _ := genericclioptions.NewTestIOStreams()
+		streams, in, out, _ := genericclioptions.NewTestIOStreams()
+		in.WriteString(tt.in)
 		cmd := NewCommand(streams)
 		cmd.SetArgs(tt.args)
 

testdata/configmap.yaml

@@ -1,3 +1,4 @@
+---
 apiVersion: v1
 kind: ConfigMap
 metadata:

testdata/deployment.yaml

@@ -1,3 +1,4 @@
+---
 apiVersion: apps/v1
 kind: Deployment
 metadata: