feat(fleetctl): User-defined columns in list-machines

Fix coreos#485

fleetctl/list_machines.go

@@ -9,53 +9,88 @@ import (
 	"github.com/coreos/fleet/machine"
 )
 
-var cmdListMachines = &Command{
-	Name:    "list-machines",
-	Summary: "Enumerate the current hosts in the cluster",
-	Usage:   "[-l|--full] [--no-legend]",
-	Description: `Lists all active machines within the cluster. Previously active machines will
-not appear in this list.
-
-For easily parsable output, you can remove the column headers:
-	fleetctl list-machines --no-legend
-
-Output the list without truncation:
-	fleetctl list-machines --full`,
-	Run: runListMachines,
-}
+const (
+	defaultListMachinesFields = "machine,ip,metadata"
+)
+
+var (
+	listMachinesFieldsFlag string
+	cmdListMachines        = &Command{
+		Name:    "list-machines",
+		Summary: "Enumerate the current hosts in the cluster",
+		Usage:   "[-l|--full] [--no-legend]",
+		Description: `Lists all active machines within the cluster. Previously active machines will
+	not appear in this list.
+
+	For easily parsable output, you can remove the column headers:
+		fleetctl list-machines --no-legend
+
+	Output the list without truncation:
+		fleetctl list-machines --full`,
+		Run: runListMachines,
+	}
+
+	listMachinesFields = map[string]machineToField{
+		"machine": func(ms *machine.MachineState, full bool) string {
+			return machineIDLegend(*ms, full)
+		},
+		"ip": func(ms *machine.MachineState, full bool) string {
+			ip := ms.PublicIP
+			if len(ip) == 0 {
+				ip = "-"
+			}
+			return ip
+		},
+		"metadata": func(ms *machine.MachineState, full bool) string {
+			metadata := "-"
+			if len(ms.Metadata) != 0 {
+				metadata = formatMetadata(ms.Metadata)
+			}
+			return metadata
+		},
+	}
+)
+
+type machineToField func(ms *machine.MachineState, full bool) string
 
 func init() {
 	cmdListMachines.Flags.BoolVar(&sharedFlags.Full, "full", false, "Do not ellipsize fields on output")
 	cmdListMachines.Flags.BoolVar(&sharedFlags.Full, "l", false, "Shorthand for --full")
 	cmdListMachines.Flags.BoolVar(&sharedFlags.NoLegend, "no-legend", false, "Do not print a legend (column headers)")
+	cmdListMachines.Flags.StringVar(&listMachinesFieldsFlag, "fields", defaultListMachinesFields, fmt.Sprintf("Columns to print for each Machine. Valid fields are %q", strings.Join(machineToFieldKeys(listMachinesFields), ",")))
 }
 
 func runListMachines(args []string) (exit int) {
-	if !sharedFlags.NoLegend {
-		fmt.Fprintln(out, "MACHINE\tIP\tMETADATA")
+	if listMachinesFieldsFlag == "" {
+		fmt.Fprintf(os.Stderr, "Must define output format\n")
+		return 1
+	}
+
+	cols := strings.Split(listMachinesFieldsFlag, ",")
+	for _, s := range cols {
+		if _, ok := listMachinesFields[s]; !ok {
+			fmt.Fprintf(os.Stderr, "Invalid key in output format: %q\n", s)
+			return 1
+		}
 	}
 
 	machines, sortable, err := findAllMachines()
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "Error retrieving list of active machines: %v\n", err)
 		return 1
 	}
-	for _, m := range sortable {
-		mach := machines[m]
-
-		ml := machineIDLegend(mach, sharedFlags.Full)
 
-		ip := mach.PublicIP
-		if len(ip) == 0 {
-			ip = "-"
-		}
+	if !sharedFlags.NoLegend {
+		fmt.Fprintln(out, strings.ToUpper(strings.Join(cols, "\t")))
+	}
 
-		metadata := "-"
-		if len(mach.Metadata) != 0 {
-			metadata = formatMetadata(mach.Metadata)
+	for _, name := range sortable {
+		var f []string
+		ms := machines[name]
+		for _, c := range cols {
+			f = append(f, listMachinesFields[c](&ms, sharedFlags.Full))
 		}
-
-		fmt.Fprintf(out, "%s\t%s\t%s\n", ml, ip, metadata)
+		fmt.Fprintln(out, strings.Join(f, "\t"))
 	}
 
 	out.Flush()
@@ -91,3 +126,10 @@ func findAllMachines() (machines map[string]machine.MachineState, sortable sort.
 
 	return
 }
+
+func machineToFieldKeys(m map[string]machineToField) (keys []string) {
+	for k, _ := range m {
+		keys = append(keys, k)
+	}
+	return
+}

fleetctl/list_machines_test.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/coreos/fleet/machine"
 	"github.com/coreos/fleet/registry"
+	"github.com/coreos/fleet/resource"
 )
 
 func newTestRegistryForListMachines() registry.Registry {
@@ -38,3 +39,43 @@ func TestGetAllMachines(t *testing.T) {
 		t.Errorf("Expected to find mnopqr as the last machine, but it was %s\n", sortable[2])
 	}
 }
+
+func TestListMachinesFieldsToStrings(t *testing.T) {
+	id := "4d389537d9d14bdabe8be54a9c29f68d"
+	ip := "192.0.2.1"
+	metadata := map[string]string{
+		"foo": "bar",
+		"ping": "pong",
+	}
+	ver := "v9.9.9"
+	res := resource.ResourceTuple{10, 1024, 1024}
+
+	ms := &machine.MachineState{id, ip, metadata, ver, res}
+
+	val := listMachinesFields["machine"](ms, false)
+	assertEqual(t, "machine", "4d389537...", val)
+
+	val = listMachinesFields["machine"](ms, true)
+	assertEqual(t, "machine", "4d389537d9d14bdabe8be54a9c29f68d", val)
+
+	val = listMachinesFields["ip"](ms, false)
+	assertEqual(t, "ip", "192.0.2.1", val)
+
+	val = listMachinesFields["metadata"](ms, false)
+	assertEqual(t, "metadata", "foo=bar, ping=pong", val)
+}
+
+func TestListMachinesFieldsEmpty(t *testing.T) {
+	id := "4d389537d9d14bdabe8be54a9c29f68d"
+	ip := ""
+	metadata := map[string]string{}
+	ver := "v9.9.9"
+	res := resource.ResourceTuple{10, 1024, 1024}
+
+	ms := &machine.MachineState{id, ip, metadata, ver, res}
+
+	for _, tt := range []string{"ip", "metadata"} {
+		f := listMachinesFields[tt](ms, false)
+		assertEqual(t, tt, "-", f)
+	}
+}