Output compact JSON by default for --format=json

With this change all `inspect` commands will output a compact JSON
representation of the elements, the default format (indented JSON) stays the
same.

Signed-off-by: Djordje Lukic <djordje.lukic@docker.com>
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cli/command/config/inspect.go

@@ -31,7 +31,7 @@ func newConfigInspectCommand(dockerCli command.Cli) *cobra.Command {
 		},
 	}
 
-	cmd.Flags().StringVarP(&opts.Format, "format", "f", "json", flagsHelper.InspectFormatHelp)
+	cmd.Flags().StringVarP(&opts.Format, "format", "f", "", flagsHelper.InspectFormatHelp)
 	cmd.Flags().BoolVar(&opts.Pretty, "pretty", false, "Print the information in a human friendly format")
 	return cmd
 }

cli/command/container/inspect.go

@@ -31,7 +31,7 @@ func newInspectCommand(dockerCli command.Cli) *cobra.Command {
 	}
 
 	flags := cmd.Flags()
-	flags.StringVarP(&opts.format, "format", "f", "json", flagsHelper.InspectFormatHelp)
+	flags.StringVarP(&opts.format, "format", "f", "", flagsHelper.InspectFormatHelp)
 	flags.BoolVarP(&opts.size, "size", "s", false, "Display total file sizes")
 
 	return cmd

cli/command/context/inspect.go

@@ -35,7 +35,7 @@ func newInspectCommand(dockerCli command.Cli) *cobra.Command {
 	}
 
 	flags := cmd.Flags()
-	flags.StringVarP(&opts.format, "format", "f", "json", flagsHelper.InspectFormatHelp)
+	flags.StringVarP(&opts.format, "format", "f", "", flagsHelper.InspectFormatHelp)
 	return cmd
 }
 

cli/command/image/inspect.go

@@ -30,7 +30,7 @@ func newInspectCommand(dockerCli command.Cli) *cobra.Command {
 	}
 
 	flags := cmd.Flags()
-	flags.StringVarP(&opts.format, "format", "f", "json", flagsHelper.InspectFormatHelp)
+	flags.StringVarP(&opts.format, "format", "f", "", flagsHelper.InspectFormatHelp)
 	return cmd
 }
 

cli/command/inspect/inspector.go

@@ -15,7 +15,9 @@ import (
 
 // Inspector defines an interface to implement to process elements
 type Inspector interface {
+	// Inspect writes the raw element in JSON format.
 	Inspect(typedElement interface{}, rawElement []byte) error
+	// Flush writes the result of inspecting all elements into the output stream.
 	Flush() error
 }
 
@@ -38,10 +40,14 @@ func NewTemplateInspector(outputStream io.Writer, tmpl *template.Template) Inspe
 // NewTemplateInspectorFromString creates a new TemplateInspector from a string
 // which is compiled into a template.
 func NewTemplateInspectorFromString(out io.Writer, tmplStr string) (Inspector, error) {
-	if tmplStr == "" || tmplStr == "json" {
+	if tmplStr == "" {
 		return NewIndentedInspector(out), nil
 	}
 
+	if tmplStr == "json" {
+		return NewJSONInspector(out), nil
+	}
+
 	tmpl, err := templates.Parse(tmplStr)
 	if err != nil {
 		return nil, errors.Errorf("Template parsing error: %s", err)
@@ -136,64 +142,80 @@ func (i *TemplateInspector) Flush() error {
 	return err
 }
 
-// IndentedInspector uses a buffer to stop the indented representation of an element.
+// NewIndentedInspector generates a new inspector with an indented representation
-type IndentedInspector struct {
+// of elements.
-	outputStream io.Writer
-	elements     []interface{}
-	rawElements  [][]byte
-}
-
-// NewIndentedInspector generates a new IndentedInspector.
 func NewIndentedInspector(outputStream io.Writer) Inspector {
-	return &IndentedInspector{
+	return &elementsInspector{
 		outputStream: outputStream,
+		raw: func(dst *bytes.Buffer, src []byte) error {
+			return json.Indent(dst, src, "", "    ")
+		},
+		el: func(v interface{}) ([]byte, error) {
+			return json.MarshalIndent(v, "", "    ")
+		},
 	}
 }
 
-// Inspect writes the raw element with an indented json format.
+// NewJSONInspector generates a new inspector with a compact representation
-func (i *IndentedInspector) Inspect(typedElement interface{}, rawElement []byte) error {
+// of elements.
+func NewJSONInspector(outputStream io.Writer) Inspector {
+	return &elementsInspector{
+		outputStream: outputStream,
+		raw:          json.Compact,
+		el:           json.Marshal,
+	}
+}
+
+type elementsInspector struct {
+	outputStream io.Writer
+	elements     []interface{}
+	rawElements  [][]byte
+	raw          func(dst *bytes.Buffer, src []byte) error
+	el           func(v interface{}) ([]byte, error)
+}
+
+func (e *elementsInspector) Inspect(typedElement interface{}, rawElement []byte) error {
 	if rawElement != nil {
-		i.rawElements = append(i.rawElements, rawElement)
+		e.rawElements = append(e.rawElements, rawElement)
 	} else {
-		i.elements = append(i.elements, typedElement)
+		e.elements = append(e.elements, typedElement)
 	}
 	return nil
 }
 
-// Flush writes the result of inspecting all elements into the output stream.
+func (e *elementsInspector) Flush() error {
-func (i *IndentedInspector) Flush() error {
+	if len(e.elements) == 0 && len(e.rawElements) == 0 {
-	if len(i.elements) == 0 && len(i.rawElements) == 0 {
+		_, err := io.WriteString(e.outputStream, "[]\n")
-		_, err := io.WriteString(i.outputStream, "[]\n")
 		return err
 	}
 
 	var buffer io.Reader
-	if len(i.rawElements) > 0 {
+	if len(e.rawElements) > 0 {
 		bytesBuffer := new(bytes.Buffer)
 		bytesBuffer.WriteString("[")
-		for idx, r := range i.rawElements {
+		for idx, r := range e.rawElements {
 			bytesBuffer.Write(r)
-			if idx < len(i.rawElements)-1 {
+			if idx < len(e.rawElements)-1 {
 				bytesBuffer.WriteString(",")
 			}
 		}
 		bytesBuffer.WriteString("]")
-		indented := new(bytes.Buffer)
+		output := new(bytes.Buffer)
-		if err := json.Indent(indented, bytesBuffer.Bytes(), "", "    "); err != nil {
+		if err := e.raw(output, bytesBuffer.Bytes()); err != nil {
 			return err
 		}
-		buffer = indented
+		buffer = output
 	} else {
-		b, err := json.MarshalIndent(i.elements, "", "    ")
+		b, err := e.el(e.elements)
 		if err != nil {
 			return err
 		}
 		buffer = bytes.NewReader(b)
 	}
 
-	if _, err := io.Copy(i.outputStream, buffer); err != nil {
+	if _, err := io.Copy(e.outputStream, buffer); err != nil {
 		return err
 	}
-	_, err := io.WriteString(i.outputStream, "\n")
+	_, err := io.WriteString(e.outputStream, "\n")
 	return err
 }

cli/command/inspect/inspector_test.go

@@ -277,11 +277,7 @@ func TestNewTemplateInspectorFromString(t *testing.T) {
 		{
 			name:     "json specific value outputs json",
 			template: "json",
-			expected: `[
+			expected: `[{"Name":"test"}]
-    {
-        "Name": "test"
-    }
-]
 `,
 		},
 		{

cli/command/network/inspect.go

@@ -30,7 +30,7 @@ func newInspectCommand(dockerCli command.Cli) *cobra.Command {
 		},
 	}
 
-	cmd.Flags().StringVarP(&opts.format, "format", "f", "json", flagsHelper.InspectFormatHelp)
+	cmd.Flags().StringVarP(&opts.format, "format", "f", "", flagsHelper.InspectFormatHelp)
 	cmd.Flags().BoolVarP(&opts.verbose, "verbose", "v", false, "Verbose output for diagnostics")
 
 	return cmd

cli/command/node/inspect.go

@@ -32,7 +32,7 @@ func newInspectCommand(dockerCli command.Cli) *cobra.Command {
 	}
 
 	flags := cmd.Flags()
-	flags.StringVarP(&opts.format, "format", "f", "json", flagsHelper.InspectFormatHelp)
+	flags.StringVarP(&opts.format, "format", "f", "", flagsHelper.InspectFormatHelp)
 	flags.BoolVar(&opts.pretty, "pretty", false, "Print the information in a human friendly format")
 	return cmd
 }

cli/command/plugin/inspect.go

@@ -29,7 +29,7 @@ func newInspectCommand(dockerCli command.Cli) *cobra.Command {
 	}
 
 	flags := cmd.Flags()
-	flags.StringVarP(&opts.format, "format", "f", "json", flagsHelper.InspectFormatHelp)
+	flags.StringVarP(&opts.format, "format", "f", "", flagsHelper.InspectFormatHelp)
 	return cmd
 }
 

cli/command/secret/inspect.go

@@ -30,7 +30,7 @@ func newSecretInspectCommand(dockerCli command.Cli) *cobra.Command {
 		},
 	}
 
-	cmd.Flags().StringVarP(&opts.format, "format", "f", "json", flagsHelper.InspectFormatHelp)
+	cmd.Flags().StringVarP(&opts.format, "format", "f", "", flagsHelper.InspectFormatHelp)
 	cmd.Flags().BoolVar(&opts.pretty, "pretty", false, "Print the information in a human friendly format")
 	return cmd
 }

cli/command/service/inspect.go

@@ -38,7 +38,7 @@ func newInspectCommand(dockerCli command.Cli) *cobra.Command {
 	}
 
 	flags := cmd.Flags()
-	flags.StringVarP(&opts.format, "format", "f", "json", flagsHelper.InspectFormatHelp)
+	flags.StringVarP(&opts.format, "format", "f", "", flagsHelper.InspectFormatHelp)
 	flags.BoolVar(&opts.pretty, "pretty", false, "Print the information in a human friendly format")
 	return cmd
 }

cli/command/system/inspect.go

@@ -37,7 +37,7 @@ func NewInspectCommand(dockerCli command.Cli) *cobra.Command {
 	}
 
 	flags := cmd.Flags()
-	flags.StringVarP(&opts.format, "format", "f", "json", flagsHelper.InspectFormatHelp)
+	flags.StringVarP(&opts.format, "format", "f", "", flagsHelper.InspectFormatHelp)
 	flags.StringVar(&opts.inspectType, "type", "", "Return JSON for specified type")
 	flags.BoolVarP(&opts.size, "size", "s", false, "Display total file sizes if the type is container")
 

cli/command/volume/inspect.go

@@ -28,7 +28,7 @@ func newInspectCommand(dockerCli command.Cli) *cobra.Command {
 		},
 	}
 
-	cmd.Flags().StringVarP(&opts.format, "format", "f", "json", flagsHelper.InspectFormatHelp)
+	cmd.Flags().StringVarP(&opts.format, "format", "f", "", flagsHelper.InspectFormatHelp)
 
 	return cmd
 }

docs/reference/commandline/config_inspect.md

@@ -15,7 +15,7 @@ Options:
   -f, --format string   Format output using a custom template:
                         'json':             Print in JSON format
                         'TEMPLATE':         Print output using the given Go template.
-                        Refer to https://docs.docker.com/go/formatting/ for more information about formatting output with templates (default "json")
+                        Refer to https://docs.docker.com/go/formatting/ for more information about formatting output with templates
       --pretty          Print the information in a human friendly format
       --help            Print usage
 ```

docs/reference/commandline/context_inspect.md

@@ -15,7 +15,7 @@ Options:
   -f, --format string   Format output using a custom template:
                         'json':             Print in JSON format
                         'TEMPLATE':         Print output using the given Go template.
-                        Refer to https://docs.docker.com/go/formatting/ for more information about formatting output with templates (default "json")
+                        Refer to https://docs.docker.com/go/formatting/ for more information about formatting output with templates
 ```
 
 ## Description

docs/reference/commandline/info.md

@@ -12,7 +12,7 @@ Usage:  docker info [OPTIONS]
 Display system-wide information
 
 Options:
-  -f, --format string   Format the output using the given Go template (default "json")
+  -f, --format string   Format the output using the given Go template
       --help            Print usage
 ```
 

docs/reference/commandline/network_inspect.md

@@ -15,7 +15,7 @@ Options:
   -f, --format string   Format output using a custom template:
                         'json':             Print in JSON format
                         'TEMPLATE':         Print output using the given Go template.
-                        Refer to https://docs.docker.com/go/formatting/ for more information about formatting output with templates (default "json")
+                        Refer to https://docs.docker.com/go/formatting/ for more information about formatting output with templates
   -v, --verbose         Verbose output for diagnostics
       --help            Print usage
 ```

docs/reference/commandline/node_inspect.md

@@ -15,7 +15,7 @@ Options:
   -f, --format string   Format output using a custom template:
                         'json':             Print in JSON format
                         'TEMPLATE':         Print output using the given Go template.
-                        Refer to https://docs.docker.com/go/formatting/ for more information about formatting output with templates (default "json")
+                        Refer to https://docs.docker.com/go/formatting/ for more information about formatting output with templates
       --pretty          Print the information in a human friendly format
       --help            Print usage
 ```

docs/reference/commandline/plugin_inspect.md

@@ -15,7 +15,7 @@ Options:
   -f, --format string   Format output using a custom template:
                         'json':             Print in JSON format
                         'TEMPLATE':         Print output using the given Go template.
-                        Refer to https://docs.docker.com/go/formatting/ for more information about formatting output with templates (default "json")
+                        Refer to https://docs.docker.com/go/formatting/ for more information about formatting output with templates
       --help            Print usage
 ```
 

docs/reference/commandline/secret_inspect.md

@@ -15,7 +15,7 @@ Options:
   -f, --format string   Format output using a custom template:
                         'json':             Print in JSON format
                         'TEMPLATE':         Print output using the given Go template.
-                        Refer to https://docs.docker.com/go/formatting/ for more information about formatting output with templates (default "json")
+                        Refer to https://docs.docker.com/go/formatting/ for more information about formatting output with templates
       --pretty          Print the information in a human friendly format
       --help            Print usage
 ```

docs/reference/commandline/service_inspect.md

@@ -15,7 +15,7 @@ Options:
   -f, --format string   Format output using a custom template:
                         'json':             Print in JSON format
                         'TEMPLATE':         Print output using the given Go template.
-                        Refer to https://docs.docker.com/go/formatting/ for more information about formatting output with templates (default "json")
+                        Refer to https://docs.docker.com/go/formatting/ for more information about formatting output with templates
       --pretty          Print the information in a human friendly format
       --help            Print usage
 ```

docs/reference/commandline/volume_inspect.md

@@ -15,7 +15,7 @@ Options:
   -f, --format string   Format output using a custom template:
                         'json':             Print in JSON format
                         'TEMPLATE':         Print output using the given Go template.
-                        Refer to https://docs.docker.com/go/formatting/ for more information about formatting output with templates (default "json")
+                        Refer to https://docs.docker.com/go/formatting/ for more information about formatting output with templates
       --help            Print usage
 ```