Add a check for size field in custom format string

This fix addresses an issue where including the `{{.Size}}` format
field in conjunction with `docker ps --format`, without the `--size`
flag, would not correctly display the size of containers.

This is done by doing a check on the custom format string, and setting
the size flag on the options struct if the field is found. This struct
gets passed to the engine API which then generates the correct query.

An integration test is included which runs `docker ps --format "table
{{.Size}}"` without `--size`, and checks that the returned output is
not `0 B`.

Fixes #21991

As suggested by @cpuguy83, a parser is implemented to process the format
string as a template, and then traverses the template tree to determine
if `.Size` was called.

This was then reworked by making use of template execution with a
pre-processor struct that will set the `--size` option if the template
calls for the field.

The pre-processor now also sets a boolean in the context passed to the
writer. There is an integration test for this that calls `docker ps
--size --format "{{.Size}}"` and then checks that `size: {{.Size}}` is
not appended, as it would with previous behavior.

Finally, a change was made to the formatter to not automatically
add a `{{.Size}}` if a custom format is provided.

Signed-off-by: Paulo Ribeiro <paigr.io@gmail.com>
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

api/client/formatter/formatter.go

@@ -114,35 +114,27 @@ type ImageContext struct {
 func (ctx ContainerContext) Write() {
 	switch ctx.Format {
 	case tableFormatKey:
-		ctx.Format = defaultContainerTableFormat
 		if ctx.Quiet {
 			ctx.Format = defaultQuietFormat
+		} else {
+			ctx.Format = defaultContainerTableFormat
+			if ctx.Size {
+				ctx.Format += `\t{{.Size}}`
+			}
 		}
 	case rawFormatKey:
 		if ctx.Quiet {
 			ctx.Format = `container_id: {{.ID}}`
 		} else {
-			ctx.Format = `container_id: {{.ID}}
-image: {{.Image}}
-command: {{.Command}}
-created_at: {{.CreatedAt}}
-status: {{.Status}}
-names: {{.Names}}
-labels: {{.Labels}}
-ports: {{.Ports}}
-`
+			ctx.Format = `container_id: {{.ID}}\nimage: {{.Image}}\ncommand: {{.Command}}\ncreated_at: {{.CreatedAt}}\nstatus: {{.Status}}\nnames: {{.Names}}\nlabels: {{.Labels}}\nports: {{.Ports}}\n`
 			if ctx.Size {
-				ctx.Format += `size: {{.Size}}
-`
+				ctx.Format += `size: {{.Size}}\n`
 			}
 		}
 	}
 
 	ctx.buffer = bytes.NewBufferString("")
 	ctx.preformat()
-	if ctx.table && ctx.Size {
-		ctx.finalFormat += "\t{{.Size}}"
-	}
 
 	tmpl, err := ctx.parseFormat()
 	if err != nil {

api/client/formatter/formatter_test.go

@@ -63,7 +63,7 @@ containerID2        ubuntu              ""                  24 hours ago
 				},
 				Size: true,
 			},
-			"IMAGE               SIZE\nubuntu              0 B\nubuntu              0 B\n",
+			"IMAGE\nubuntu\nubuntu\n",
 		},
 		{
 			ContainerContext{
@@ -230,6 +230,25 @@ func TestContainerContextWriteWithNoContainers(t *testing.T) {
 				},
 				Size: true,
 			},
+			"IMAGE\n",
+		},
+		{
+			ContainerContext{
+				Context: Context{
+					Format: "table {{.Image}}\t{{.Size}}",
+					Output: out,
+				},
+			},
+			"IMAGE               SIZE\n",
+		},
+		{
+			ContainerContext{
+				Context: Context{
+					Format: "table {{.Image}}\t{{.Size}}",
+					Output: out,
+				},
+				Size: true,
+			},
 			"IMAGE               SIZE\n",
 		},
 	}

api/client/ps.go

@@ -2,15 +2,27 @@ package client
 
 import (
 	"golang.org/x/net/context"
+	"io/ioutil"
 
 	"github.com/docker/docker/api/client/formatter"
 	Cli "github.com/docker/docker/cli"
 	"github.com/docker/docker/opts"
 	flag "github.com/docker/docker/pkg/mflag"
+	"github.com/docker/docker/utils/templates"
 	"github.com/docker/engine-api/types"
 	"github.com/docker/engine-api/types/filters"
 )
 
+type preProcessor struct {
+	opts *types.ContainerListOptions
+}
+
+// Size sets the size option when called by a template execution.
+func (p *preProcessor) Size() bool {
+	p.opts.Size = true
+	return true
+}
+
 // CmdPs outputs a list of Docker containers.
 //
 // Usage: docker ps [OPTIONS]
@@ -54,6 +66,14 @@ func (cli *DockerCli) CmdPs(args ...string) error {
 		Filter: psFilterArgs,
 	}
 
+	pre := &preProcessor{opts: &options}
+	tmpl, err := templates.Parse(*format)
+	if err != nil {
+		return err
+	}
+
+	_ = tmpl.Execute(ioutil.Discard, pre)
+
 	containers, err := cli.client.ContainerList(context.Background(), options)
 	if err != nil {
 		return err

integration-cli/docker_cli_ps_test.go

@@ -787,3 +787,20 @@ func (s *DockerSuite) TestPsShowMounts(c *check.C) {
 	out, _ = dockerCmd(c, "ps", "--format", "{{.Names}} {{.Mounts}}", "--filter", "volume="+prefix+slash+"this-path-was-never-mounted")
 	c.Assert(strings.TrimSpace(string(out)), checker.HasLen, 0)
 }
+
+func (s *DockerSuite) TestPsFormatSize(c *check.C) {
+	testRequires(c, DaemonIsLinux)
+	runSleepingContainer(c)
+
+	out, _ := dockerCmd(c, "ps", "--format", "table {{.Size}}")
+	lines := strings.Split(out, "\n")
+	c.Assert(lines[1], checker.Not(checker.Equals), "0 B", check.Commentf("Should not display a size of 0 B"))
+
+	out, _ = dockerCmd(c, "ps", "--size", "--format", "table {{.Size}}")
+	lines = strings.Split(out, "\n")
+	c.Assert(lines[0], checker.Equals, "SIZE", check.Commentf("Should only have one size column"))
+
+	out, _ = dockerCmd(c, "ps", "--size", "--format", "raw")
+	lines = strings.Split(out, "\n")
+	c.Assert(lines[8], checker.HasPrefix, "size:", check.Commentf("Size should be appended on a newline"))
+}