Add filtering contexts

cmd/kubectx/flags.go

@@ -40,6 +40,16 @@ func parseArgs(argv []string) Op {
 		return ListOp{}
 	}
 
+	if argv[0] == "--list" || argv[0] == "-l" {
+		if len(argv) == 1 {
+			return ListOp{}
+		}
+		if filters, ok := parseFilterSyntax(argv[1:]); ok {
+			return ListOp{Filters: filters}
+		}
+		return UnsupportedOp{Err: fmt.Errorf("'-l' filters must use A=B format")}
+	}
+
 	if argv[0] == "-d" {
 		if len(argv) == 1 {
 			if cmdutil.IsInteractiveMode(os.Stdout) {

cmd/kubectx/flags_test.go

@@ -39,6 +39,21 @@ func Test_parseArgs_new(t *testing.T) {
 		{name: "help long form",
 			args: []string{"--help"},
 			want: HelpOp{}},
+		{name: "list shorthand",
+			args: []string{"-l"},
+			want: ListOp{}},
+		{name: "list long form",
+			args: []string{"--list"},
+			want: ListOp{}},
+		{name: "list long form filters",
+			args: []string{"--list", "cluster=cl"},
+			want: ListOp{Filters: map[string]string{"cluster": "cl"}}},
+		{name: "list long form filters - wrong syntax",
+			args: []string{"--list", "cluster-cl"},
+			want: UnsupportedOp{fmt.Errorf("'-l' filters must use A=B format")}},
+		{name: "current long form",
+			args: []string{"--current"},
+			want: CurrentOp{}},
 		{name: "current shorthand",
 			args: []string{"-c"},
 			want: CurrentOp{}},

cmd/kubectx/fzf.go

@@ -88,7 +88,7 @@ func (op InteractiveDeleteOp) Run(_, stderr io.Writer) error {
 	}
 	kc.Close()
 
-	if len(kc.ContextNames()) == 0 {
+	if len(kc.ContextNames(nil)) == 0 {
 		return errors.New("no contexts found in config")
 	}
 

cmd/kubectx/list.go

@@ -17,6 +17,7 @@ package main
 import (
 	"fmt"
 	"io"
+	"strings"
 
 	"facette.io/natsort"
 	"github.com/pkg/errors"
@@ -27,9 +28,29 @@ import (
 )
 
 // ListOp describes listing contexts.
-type ListOp struct{}
+type ListOp struct {
+	Filters map[string]string
+}
 
-func (_ ListOp) Run(stdout, stderr io.Writer) error {
+// parseFilterSyntax parses multiple A=B form into a map[A]=B and returns
+// whether it is parsed correctly.
+func parseFilterSyntax(v []string) (map[string]string, bool) {
+	m := make(map[string]string)
+	for _, vv := range v {
+		s := strings.Split(vv, "=")
+		if len(s) != 2 {
+			return nil, false
+		}
+		key, value := s[0], s[1]
+		if key == "" || value == "" {
+			return nil, false
+		}
+		m[key] = value
+	}
+	return m, true
+}
+
+func (op ListOp) Run(stdout, stderr io.Writer) error {
 	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
 	defer kc.Close()
 	if err := kc.Parse(); err != nil {
@@ -40,7 +61,7 @@ func (_ ListOp) Run(stdout, stderr io.Writer) error {
 		return errors.Wrap(err, "kubeconfig error")
 	}
 
-	ctxs := kc.ContextNames()
+	ctxs := kc.ContextNames(op.Filters)
 	natsort.Sort(ctxs)
 
 	cur := kc.GetCurrentContext()

internal/kubeconfig/contexts.go

@@ -44,7 +44,7 @@ func (k *Kubeconfig) contextNode(name string) (*yaml.Node, error) {
 	return nil, errors.Errorf("context with name \"%s\" not found", name)
 }
 
-func (k *Kubeconfig) ContextNames() []string {
+func (k *Kubeconfig) ContextNames(filters map[string]string) []string {
 	contexts := valueOf(k.rootNode, "contexts")
 	if contexts == nil {
 		return nil
@@ -54,8 +54,19 @@ func (k *Kubeconfig) ContextNames() []string {
 	}
 
 	var ctxNames []string
+ctxLoop:
 	for _, ctx := range contexts.Content {
 		nameVal := valueOf(ctx, "name")
+		for k, v := range filters {
+			ctxVal := valueOf(ctx, "context")
+			if ctxVal == nil {
+				continue ctxLoop
+			}
+			vVal := valueOf(ctxVal, k)
+			if vVal == nil || vVal.Value != v {
+				continue ctxLoop
+			}
+		}
 		if nameVal != nil {
 			ctxNames = append(ctxNames, nameVal.Value)
 		}
@@ -64,7 +75,7 @@ func (k *Kubeconfig) ContextNames() []string {
 }
 
 func (k *Kubeconfig) ContextExists(name string) bool {
-	ctxNames := k.ContextNames()
+	ctxNames := k.ContextNames(nil)
 	for _, v := range ctxNames {
 		if v == name {
 			return true

internal/kubeconfig/contexts_test.go

@@ -33,20 +33,39 @@ func TestKubeconfig_ContextNames(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	ctx := kc.ContextNames()
+	ctx := kc.ContextNames(nil)
 	expected := []string{"abc", "def", "ghi"}
 	if diff := cmp.Diff(expected, ctx); diff != "" {
 		t.Fatalf("%s", diff)
 	}
 }
 
+func TestKubeconfig_ContextNames_Filtered(t *testing.T) {
+	tl := WithMockKubeconfigLoader(
+		testutil.KC().WithCtxs(
+			testutil.Ctx("abc").Ns("ns1"),
+			testutil.Ctx("def"),
+			testutil.Ctx("ghi").Ns("ns2"),
+		).Set("field1", map[string]string{"bar": "zoo"}).ToYAML(t))
+	kc := new(Kubeconfig).WithLoader(tl)
+	if err := kc.Parse(); err != nil {
+		t.Fatal(err)
+	}
+
+	ctx := kc.ContextNames(map[string]string{"namespace": "ns2"})
+	expected := []string{"ghi"}
+	if diff := cmp.Diff(expected, ctx); diff != "" {
+		t.Fatalf("%s", diff)
+	}
+}
+
 func TestKubeconfig_ContextNames_noContextsEntry(t *testing.T) {
 	tl := WithMockKubeconfigLoader(`a: b`)
 	kc := new(Kubeconfig).WithLoader(tl)
 	if err := kc.Parse(); err != nil {
 		t.Fatal(err)
 	}
-	ctx := kc.ContextNames()
+	ctx := kc.ContextNames(nil)
 	var expected []string = nil
 	if diff := cmp.Diff(expected, ctx); diff != "" {
 		t.Fatalf("%s", diff)
@@ -59,7 +78,7 @@ func TestKubeconfig_ContextNames_nonArrayContextsEntry(t *testing.T) {
 	if err := kc.Parse(); err != nil {
 		t.Fatal(err)
 	}
-	ctx := kc.ContextNames()
+	ctx := kc.ContextNames(nil)
 	var expected []string = nil
 	if diff := cmp.Diff(expected, ctx); diff != "" {
 		t.Fatalf("%s", diff)