Add format to the docker system df command

Signed-off-by: Boaz Shuster <ripcurld.github@gmail.com>

command/formatter/disk_usage.go

@@ -45,15 +45,33 @@ func (ctx *DiskUsageContext) startSubsection(format string) (*template.Template,
 	return ctx.parseFormat()
 }
 
-func (ctx *DiskUsageContext) Write() {
+//
+// NewDiskUsageFormat returns a format for rendering an DiskUsageContext
+func NewDiskUsageFormat(source string) Format {
+	switch source {
+	case TableFormatKey:
+		format := defaultDiskUsageTableFormat
+		return Format(format)
+	case RawFormatKey:
+		format := `type: {{.Type}}
+total: {{.TotalCount}}
+active: {{.Active}}
+size: {{.Size}}
+reclaimable: {{.Reclaimable}}
+`
+		return Format(format)
+	}
+	return Format(source)
+}
+
+func (ctx *DiskUsageContext) Write() (err error) {
 	if ctx.Verbose == false {
 		ctx.buffer = bytes.NewBufferString("")
-		ctx.Format = defaultDiskUsageTableFormat
 		ctx.preFormat()
 
 		tmpl, err := ctx.parseFormat()
 		if err != nil {
-			return
+			return err
 		}
 
 		err = ctx.contextFormat(tmpl, &diskUsageImagesContext{
@@ -61,20 +79,20 @@ func (ctx *DiskUsageContext) Write() {
 			images:    ctx.Images,
 		})
 		if err != nil {
-			return
+			return err
 		}
 		err = ctx.contextFormat(tmpl, &diskUsageContainersContext{
 			containers: ctx.Containers,
 		})
 		if err != nil {
-			return
+			return err
 		}
 
 		err = ctx.contextFormat(tmpl, &diskUsageVolumesContext{
 			volumes: ctx.Volumes,
 		})
 		if err != nil {
-			return
+			return err
 		}
 
 		diskUsageContainersCtx := diskUsageContainersContext{containers: []*types.Container{}}
@@ -87,7 +105,7 @@ func (ctx *DiskUsageContext) Write() {
 		}
 		ctx.postFormat(tmpl, &diskUsageContainersCtx)
 
-		return
+		return err
 	}
 
 	// First images
@@ -158,6 +176,7 @@ func (ctx *DiskUsageContext) Write() {
 		}
 	}
 	ctx.postFormat(tmpl, newVolumeContext())
+	return
 }
 
 type diskUsageImagesContext struct {

command/formatter/disk_usage_test.go

@@ -8,13 +8,17 @@ import (
 )
 
 func TestDiskUsageContextFormatWrite(t *testing.T) {
-	// Check default output format (verbose and non-verbose mode) for table headers
 	cases := []struct {
 		context  DiskUsageContext
 		expected string
 	}{
+		// Check default output format (verbose and non-verbose mode) for table headers
 		{
-			DiskUsageContext{Verbose: false},
+			DiskUsageContext{
+				Context: Context{
+					Format: NewDiskUsageFormat("table"),
+				},
+				Verbose: false},
 			`TYPE                TOTAL               ACTIVE              SIZE                RECLAIMABLE
 Images              0                   0                   0B                  0B
 Containers          0                   0                   0B                  0B
@@ -34,6 +38,77 @@ CONTAINER ID        IMAGE               COMMAND             LOCAL VOLUMES
 Local Volumes space usage:
 
 VOLUME NAME         LINKS               SIZE
+`,
+		},
+		// Errors
+		{
+			DiskUsageContext{
+				Context: Context{
+					Format: "{{InvalidFunction}}",
+				},
+			},
+			`Template parsing error: template: :1: function "InvalidFunction" not defined
+`,
+		},
+		{
+			DiskUsageContext{
+				Context: Context{
+					Format: "{{nil}}",
+				},
+			},
+			`Template parsing error: template: :1:2: executing "" at <nil>: nil is not a command
+`,
+		},
+		// Table Format
+		{
+			DiskUsageContext{
+				Context: Context{
+					Format: NewDiskUsageFormat("table"),
+				},
+			},
+			`TYPE                TOTAL               ACTIVE              SIZE                RECLAIMABLE
+Images              0                   0                   0B                  0B
+Containers          0                   0                   0B                  0B
+Local Volumes       0                   0                   0B                  0B
+`,
+		},
+		{
+			DiskUsageContext{
+				Context: Context{
+					Format: NewDiskUsageFormat("table {{.Type}}\t{{.Active}}"),
+				},
+			},
+			`TYPE                ACTIVE
+Images              0
+Containers          0
+Local Volumes       0
+`,
+		},
+		// Raw Format
+		{
+			DiskUsageContext{
+				Context: Context{
+					Format: NewDiskUsageFormat("raw"),
+				},
+			},
+			`type: Images
+total: 0
+active: 0
+size: 0B
+reclaimable: 0B
+
+type: Containers
+total: 0
+active: 0
+size: 0B
+reclaimable: 0B
+
+type: Local Volumes
+total: 0
+active: 0
+size: 0B
+reclaimable: 0B
+
 `,
 		},
 	}
@@ -41,7 +116,10 @@ VOLUME NAME         LINKS               SIZE
 	for _, testcase := range cases {
 		out := bytes.NewBufferString("")
 		testcase.context.Output = out
-		testcase.context.Write()
+		if err := testcase.context.Write(); err != nil {
-		assert.Equal(t, out.String(), testcase.expected)
+			assert.Equal(t, err.Error(), testcase.expected)
+		} else {
+			assert.Equal(t, out.String(), testcase.expected)
+		}
 	}
 }

command/system/df.go

@@ -1,6 +1,8 @@
 package system
 
 import (
+	"errors"
+
 	"github.com/docker/docker/cli"
 	"github.com/docker/docker/cli/command"
 	"github.com/docker/docker/cli/command/formatter"
@@ -10,6 +12,7 @@ import (
 
 type diskUsageOptions struct {
 	verbose bool
+	format  string
 }
 
 // NewDiskUsageCommand creates a new cobra.Command for `docker df`
@@ -29,19 +32,30 @@ func NewDiskUsageCommand(dockerCli *command.DockerCli) *cobra.Command {
 	flags := cmd.Flags()
 
 	flags.BoolVarP(&opts.verbose, "verbose", "v", false, "Show detailed information on space usage")
+	flags.StringVar(&opts.format, "format", "", "Pretty-print images using a Go template")
 
 	return cmd
 }
 
 func runDiskUsage(dockerCli *command.DockerCli, opts diskUsageOptions) error {
+	if opts.verbose && len(opts.format) != 0 {
+		return errors.New("the verbose and the format options conflict")
+	}
+
 	du, err := dockerCli.Client().DiskUsage(context.Background())
 	if err != nil {
 		return err
 	}
 
+	format := opts.format
+	if len(format) == 0 {
+		format = formatter.TableFormatKey
+	}
+
 	duCtx := formatter.DiskUsageContext{
 		Context: formatter.Context{
 			Output: dockerCli.Out(),
+			Format: formatter.NewDiskUsageFormat(format),
 		},
 		LayersSize: du.LayersSize,
 		Images:     du.Images,
@@ -50,7 +64,5 @@ func runDiskUsage(dockerCli *command.DockerCli, opts diskUsageOptions) error {
 		Verbose:    opts.verbose,
 	}
 
-	duCtx.Write()
+	return duCtx.Write()
-
-	return nil
 }