Add json output to skaffold schema list (#4385)

Fixes #4382

Signed-off-by: David Gageot <[email protected]>

cmd/skaffold/app/cmd/schema.go

@@ -21,6 +21,7 @@ import (
 	"io"
 
 	"github.com/spf13/cobra"
+	"github.com/spf13/pflag"
 
 	"github.com/GoogleContainerTools/skaffold/cmd/skaffold/app/cmd/schema"
 )
@@ -40,6 +41,10 @@ func NewCmdSchemaList() *cobra.Command {
 	return NewCmd("list").
 		WithDescription("List skaffold.yaml's json schema versions").
 		WithExample("List all the versions", "schema list").
+		WithExample("List all the versions, in json format", "schema list -o json").
+		WithFlags(func(f *pflag.FlagSet) {
+			f.StringVarP(&schema.OutputType, "output", "o", "plain", "Type of output: `plain` or `json`.")
+		}).
 		NoArgs(schema.List)
 }
 

cmd/skaffold/app/cmd/schema/list.go

@@ -18,17 +18,55 @@ package schema
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"io"
 
 	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/schema"
 )
 
+var OutputType string
+
 // List prints to `out` all supported schema versions.
 func List(_ context.Context, out io.Writer) error {
-	for _, version := range schema.SchemaVersions {
-		fmt.Fprintln(out, version.APIVersion)
+	return list(out, OutputType)
+}
+
+func list(out io.Writer, outputType string) error {
+	switch outputType {
+	case "json":
+		return printJSON(out)
+	case "plain":
+		return printPlain(out)
+	default:
+		return fmt.Errorf(`invalid output type: %q. Must be "plain" or "json"`, outputType)
+	}
+}
+
+type schemaList struct {
+	Versions []string `json:"versions"`
+}
+
+func printJSON(out io.Writer) error {
+	return json.NewEncoder(out).Encode(schemaList{
+		Versions: versions(),
+	})
+}
+
+func printPlain(out io.Writer) error {
+	for _, version := range versions() {
+		fmt.Fprintln(out, version)
 	}
 
 	return nil
 }
+
+func versions() []string {
+	var versions []string
+
+	for _, version := range schema.SchemaVersions {
+		versions = append(versions, version.APIVersion)
+	}
+
+	return versions
+}

cmd/skaffold/app/cmd/schema/list_test.go

@@ -18,22 +18,22 @@ package schema
 
 import (
 	"bytes"
-	"context"
+	"fmt"
 	"strings"
 	"testing"
 
 	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/schema/latest"
 	"github.com/GoogleContainerTools/skaffold/testutil"
 )
 
-func TestList(t *testing.T) {
+func TestListPlain(t *testing.T) {
 	testutil.Run(t, "", func(t *testutil.T) {
 		var out bytes.Buffer
 
-		err := List(context.Background(), &out)
+		err := list(&out, "plain")
+		t.CheckNoError(err)
 
 		versions := out.String()
-		t.CheckNoError(err)
 		t.CheckTrue(strings.HasSuffix(versions, latest.Version+"\n"))
 		t.CheckTrue(strings.HasPrefix(versions, `skaffold/v1alpha1
 skaffold/v1alpha2
@@ -61,3 +61,25 @@ skaffold/v1
 skaffold/v2alpha1`))
 	})
 }
+
+func TestListJson(t *testing.T) {
+	testutil.Run(t, "", func(t *testutil.T) {
+		var out bytes.Buffer
+
+		err := list(&out, "json")
+		t.CheckNoError(err)
+
+		versions := out.String()
+		t.CheckTrue(strings.HasPrefix(versions, `{"versions":["skaffold/v1alpha1","skaffold/v1alpha2",`))
+		t.CheckTrue(strings.HasSuffix(versions, fmt.Sprintf(",\"%s\"]}\n", latest.Version)))
+	})
+}
+
+func TestListInvalidType(t *testing.T) {
+	testutil.Run(t, "", func(t *testutil.T) {
+		var out bytes.Buffer
+
+		err := list(&out, "invalid")
+		t.CheckErrorContains(`invalid output type: "invalid". Must be "plain" or "json"`, err)
+	})
+}

docs/content/en/docs/references/cli/_index.md

@@ -869,13 +869,22 @@ Examples:
   # List all the versions
   skaffold schema list
 
+  # List all the versions, in json format
+  skaffold schema list -o json
+
+Options:
+  -o, --output='plain': Type of output: `plain` or `json`.
+
 Usage:
   skaffold schema list [options]
 
 Use "skaffold options" for a list of global command-line options (applies to all commands).
 
 
 ```
+Env vars:
+
+* `SKAFFOLD_OUTPUT` (same as `--output`)
 
 ### skaffold survey