Support nomad CLI output with JSON and template format

command/alloc_status.go

@@ -38,11 +38,17 @@ Alloc Status Options:
   -short
     Display short output. Shows only the most recent task event.
 
-  -stats 
-    Display detailed resource usage statistics
+  -stats
+    Display detailed resource usage statistics.
 
   -verbose
     Show full information.
+
+  -json
+    Output the allocation in its JSON format.
+
+  -t
+    Format and display allocation using a Go template.
 `
 
 	return strings.TrimSpace(helpText)
@@ -53,25 +59,23 @@ func (c *AllocStatusCommand) Synopsis() string {
 }
 
 func (c *AllocStatusCommand) Run(args []string) int {
-	var short, displayStats, verbose bool
+	var short, displayStats, verbose, json bool
+	var tmpl string
 
 	flags := c.Meta.FlagSet("alloc-status", FlagSetClient)
 	flags.Usage = func() { c.Ui.Output(c.Help()) }
 	flags.BoolVar(&short, "short", false, "")
 	flags.BoolVar(&verbose, "verbose", false, "")
 	flags.BoolVar(&displayStats, "stats", false, "")
+	flags.BoolVar(&json, "json", false, "")
+	flags.StringVar(&tmpl, "t", "", "")
 
 	if err := flags.Parse(args); err != nil {
 		return 1
 	}
 
 	// Check that we got exactly one allocation ID
 	args = flags.Args()
-	if len(args) != 1 {
-		c.Ui.Error(c.Help())
-		return 1
-	}
-	allocID := args[0]
 
 	// Get the HTTP client
 	client, err := c.Meta.Client()
@@ -80,6 +84,50 @@ func (c *AllocStatusCommand) Run(args []string) int {
 		return 1
 	}
 
+	// If args not specified but output format is specified, format and output the allocations data list
+	if len(args) == 0 {
+		var format string
+		if json && len(tmpl) > 0 {
+			c.Ui.Error("Both -json and -t are not allowed")
+			return 1
+		} else if json {
+			format = "json"
+		} else if len(tmpl) > 0 {
+			format = "template"
+		}
+		if len(format) > 0 {
+			allocs, _, err := client.Allocations().List(nil)
+			if err != nil {
+				c.Ui.Error(fmt.Sprintf("Error querying allocations: %v", err))
+				return 1
+			}
+			// Return nothing if no allocations found
+			if len(allocs) == 0 {
+				return 0
+			}
+
+			f, err := DataFormat(format, tmpl)
+			if err != nil {
+				c.Ui.Error(fmt.Sprintf("Error getting formatter: %s", err))
+				return 1
+			}
+
+			out, err := f.TransformData(allocs)
+			if err != nil {
+				c.Ui.Error(fmt.Sprintf("Error formatting the data: %s", err))
+				return 1
+			}
+			c.Ui.Output(out)
+			return 0
+		}
+	}
+
+	if len(args) != 1 {
+		c.Ui.Error(c.Help())
+		return 1
+	}
+	allocID := args[0]
+
 	// Truncate the id unless full length is requested
 	length := shortId
 	if verbose {
@@ -130,6 +178,32 @@ func (c *AllocStatusCommand) Run(args []string) int {
 		return 1
 	}
 
+	// If output format is specified, format and output the data
+	var format string
+	if json && len(tmpl) > 0 {
+		c.Ui.Error("Both -json and -t are not allowed")
+		return 1
+	} else if json {
+		format = "json"
+	} else if len(tmpl) > 0 {
+		format = "template"
+	}
+	if len(format) > 0 {
+		f, err := DataFormat(format, tmpl)
+		if err != nil {
+			c.Ui.Error(fmt.Sprintf("Error getting formatter: %s", err))
+			return 1
+		}
+
+		out, err := f.TransformData(alloc)
+		if err != nil {
+			c.Ui.Error(fmt.Sprintf("Error formatting the data: %s", err))
+			return 1
+		}
+		c.Ui.Output(out)
+		return 0
+	}
+
 	var statsErr error
 	var stats *api.AllocResourceUsage
 	stats, statsErr = client.Allocations().Stats(alloc, nil)

command/alloc_status_test.go

@@ -61,5 +61,13 @@ func TestAllocStatusCommand_Fails(t *testing.T) {
 	if out := ui.ErrorWriter.String(); !strings.Contains(out, "No allocation(s) with prefix or id") {
 		t.Fatalf("expected not found error, got: %s", out)
 	}
+	ui.ErrorWriter.Reset()
 
+	// Failed on both -json and -t options are specified
+	if code := cmd.Run([]string{"-address=" + url, "-json", "-t", "{{.ID}}"}); code != 1 {
+		t.Fatalf("expected exit 1, got: %d", code)
+	}
+	if out := ui.ErrorWriter.String(); !strings.Contains(out, "Both -json and -t are not allowed") {
+		t.Fatalf("expected getting formatter error, got: %s", out)
+	}
 }

command/data_format.go

@@ -0,0 +1,65 @@
+package command
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"text/template"
+)
+
+//DataFormatter is a transformer of the data.
+type DataFormatter interface {
+	// TransformData should return transformed string data.
+	TransformData(interface{}) (string, error)
+}
+
+// DataFormat returns the data formatter specified format.
+func DataFormat(format, tmpl string) (DataFormatter, error) {
+	switch format {
+	case "json":
+		if len(tmpl) > 0 {
+			return nil, fmt.Errorf("json format does not support template option.")
+		}
+		return &JSONFormat{}, nil
+	case "template":
+		return &TemplateFormat{tmpl}, nil
+	}
+	return nil, fmt.Errorf("Unsupported format is specified.")
+}
+
+type JSONFormat struct {
+}
+
+// TransformData returns JSON format string data.
+func (p *JSONFormat) TransformData(data interface{}) (string, error) {
+	out, err := json.MarshalIndent(&data, "", "    ")
+	if err != nil {
+		return "", err
+	}
+
+	return string(out), nil
+}
+
+type TemplateFormat struct {
+	tmpl string
+}
+
+// TransformData returns template format string data.
+func (p *TemplateFormat) TransformData(data interface{}) (string, error) {
+	var out io.Writer = new(bytes.Buffer)
+	if len(p.tmpl) == 0 {
+		return "", fmt.Errorf("template needs to be specified the golang templates.")
+	}
+
+	t, err := template.New("format").Parse(p.tmpl)
+	if err != nil {
+		return "", err
+	}
+
+	err = t.Execute(out, data)
+	if err != nil {
+		return "", err
+	}
+	return fmt.Sprint(out), nil
+}

command/data_format_test.go

@@ -0,0 +1,64 @@
+package command
+
+import (
+	"strings"
+	"testing"
+)
+
+type testData struct {
+	Region string
+	ID     string
+	Name   string
+}
+
+const expectJSON = `{
+    "Region": "global",
+    "ID": "1",
+    "Name": "example"
+}`
+
+var (
+	tData        = testData{"global", "1", "example"}
+	testFormat   = map[string]string{"json": "", "template": "{{.Region}}"}
+	expectOutput = map[string]string{"json": expectJSON, "template": "global"}
+)
+
+func TestDataFormat(t *testing.T) {
+	for k, v := range testFormat {
+		fm, err := DataFormat(k, v)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+
+		result, err := fm.TransformData(tData)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+
+		if result != expectOutput[k] {
+			t.Fatalf("expected output: %s, actual: %s", expectOutput[k], result)
+		}
+	}
+}
+
+func TestInvalidJSONTemplate(t *testing.T) {
+	// Invalid template {{.foo}}
+	fm, err := DataFormat("template", "{{.foo}}")
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	_, err = fm.TransformData(tData)
+	if !strings.Contains(err.Error(), "foo is not a field of struct type command.testData") {
+		t.Fatalf("expected invalid template error, got: %s", err.Error())
+	}
+
+	// No template is specified
+	fm, err = DataFormat("template", "")
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	_, err = fm.TransformData(tData)
+	if !strings.Contains(err.Error(), "template needs to be specified the golang templates.") {
+		t.Fatalf("expected not specified template error, got: %s", err.Error())
+	}
+}