Add --filename option to generate kube

This allows writing output directly to a file, instead of STDOUT.
Makes things easier for some scripting tasks. Like the unit tests
for 'play kube'.

Signed-off-by: Matthew Heon <matthew.heon@pm.me>

cmd/podman/cliconfig/config.go

@@ -145,7 +145,8 @@ type ExportValues struct {
 }
 type GenerateKubeValues struct {
 	PodmanCommand
-	Service bool
+	Service  bool
+	Filename string
 }
 
 type GenerateSystemdValues struct {

cmd/podman/generate_kube.go

@@ -2,6 +2,9 @@ package main
 
 import (
 	"fmt"
+	"io/ioutil"
+	"os"
+
 	"github.com/containers/libpod/cmd/podman/cliconfig"
 	"github.com/containers/libpod/pkg/adapter"
 	podmanVersion "github.com/containers/libpod/version"
@@ -37,6 +40,7 @@ func init() {
 	containerKubeCommand.SetUsageTemplate(UsageTemplate())
 	flags := containerKubeCommand.Flags()
 	flags.BoolVarP(&containerKubeCommand.Service, "service", "s", false, "Generate YAML for kubernetes service object")
+	flags.StringVarP(&containerKubeCommand.Filename, "filename", "f", "", "Filename to output to")
 }
 
 func generateKubeYAMLCmd(c *cliconfig.GenerateKubeValues) error {
@@ -88,8 +92,19 @@ func generateKubeYAMLCmd(c *cliconfig.GenerateKubeValues) error {
 		output = append(output, []byte("---\n")...)
 		output = append(output, marshalledService...)
 	}
-	// Output the v1.Pod with the v1.Container
-	fmt.Println(string(output))
+
+	if c.Filename != "" {
+		if _, err := os.Stat(c.Filename); err == nil {
+			return errors.Errorf("cannot write to %q - file exists", c.Filename)
+		}
+
+		if err := ioutil.WriteFile(c.Filename, output, 0644); err != nil {
+			return err
+		}
+	} else {
+		// Output the v1.Pod with the v1.Container
+		fmt.Println(string(output))
+	}
 
 	return nil
 }

completions/bash/podman

@@ -2467,7 +2467,9 @@ _podman_healthcheck_run() {
 }
 
 _podman_generate_kube() {
-    local options_with_args=""
+     local options_with_args="
+     --filename -f
+     "
 
     local boolean_options="
     -h

docs/podman-generate-kube.1.md

@@ -14,6 +14,10 @@ Note that the generated Kubernetes YAML file can be used to re-run the deploymen
 
 ## OPTIONS:
 
+**--filename**, **-f**=**filename**
+
+Output to the given file, instead of STDOUT. If the file already exists, `generate kube` will refuse to replace it and return an error.
+
 **--service**, **-s**
 
 Generate a Kubernetes service object in addition to the Pods. Used to generate a Service specification for the corresponding Pod ouput. In particular, if the object has portmap bindings, the service specification will include a NodePort declaration to expose the service. A

test/e2e/generate_kube_test.go

@@ -3,7 +3,6 @@
 package integration
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 
@@ -120,14 +119,11 @@ var _ = Describe("Podman generate kube", func() {
 		session2.WaitWithDefaultTimeout()
 		Expect(session2.ExitCode()).To(Equal(0))
 
-		kube := podmanTest.Podman([]string{"generate", "kube", podName})
+		outputFile := filepath.Join(podmanTest.RunRoot, "pod.yaml")
+		kube := podmanTest.Podman([]string{"generate", "kube", "-f", outputFile, podName})
 		kube.WaitWithDefaultTimeout()
 		Expect(kube.ExitCode()).To(Equal(0))
 
-		outputFile := filepath.Join(podmanTest.RunRoot, "pod.yaml")
-		err := ioutil.WriteFile(outputFile, []byte(kube.OutputToString()), 0644)
-		Expect(err).To(BeNil())
-
 		session3 := podmanTest.Podman([]string{"pod", "rm", "-af"})
 		session3.WaitWithDefaultTimeout()
 		Expect(session3.ExitCode()).To(Equal(0))