feat(helm): support array index format for --set.

This adds support for specifying list position with an array index using
`--set`. For example, this now works: `--set servers[0].port=8080`

cmd/helm/installer/install.go

@@ -107,7 +107,6 @@ func DeploymentManifest(opts *Options) (string, error) {
 // resource.
 func ServiceManifest(namespace string) (string, error) {
 	obj := service(namespace)
-
 	buf, err := yaml.Marshal(obj)
 	return string(buf), err
 }

docs/chart_best_practices/values.md

@@ -113,6 +113,11 @@ servers:
     port: 81
 ```
 
+The above cannot be expressed with `--set` in Helm `<=2.4`. In Helm 2.5, the
+accessing the port on foo is `--set servers[0].port=80`. Not only is it harder
+for the user to figure out, but it is prone to errors if at some later time the
+order of the `servers` is changed.
+
 Easy to use:
 
 ```yaml
@@ -123,6 +128,8 @@ servers:
     port: 81
 ```
 
+Accessing foo's port is much more obvious: `--set servers.foo.port=80`.
+
 ## Document 'values.yaml'
 
 Every defined property in 'values.yaml' should be documented. The documentation string should begin with the name of the property that it describes, and then give at least a one-sentence description.
@@ -145,4 +152,4 @@ serverPort = 9191
 
 ```
 
-Beginning each comment with the name of the parameter it documents makes it easy to grep out documentation, and will enable documentation tools to reliably correlate doc strings with the parameters they describe.
+Beginning each comment with the name of the parameter it documents makes it easy to grep out documentation, and will enable documentation tools to reliably correlate doc strings with the parameters they describe.

docs/using_helm.md

@@ -264,6 +264,22 @@ name:
   - c
 ```
 
+As of Helm 2.5.0, it is possible to access list items using an array index syntax.
+For example, `--set servers[0].port=80` becomes:
+
+```yaml
+servers:
+  - port: 80
+```
+
+Multiple values can be set this way. The line `--set servers[0].port=80,servers[0].host=example` becomes:
+
+```yaml
+servers:
+  - port: 80
+    host: example
+```
+
 Sometimes you need to use special characters in your `--set` lines. You can use
 a backslash to escape the characters; `--set name=value1\,value2` will become:
 
@@ -280,9 +296,9 @@ nodeSelector:
   kubernetes.io/role: master
 ```
 
-The `--set` syntax is not as expressive as YAML, especially when it comes to
-collections. And there is currently no method for expressing things such as "set
-the third item in a list to...".
+Deeply nested datastructures can be difficult to express using `--set`. Chart
+designers are encouraged to consider the `--set` usage when designing the format
+of a `values.yaml` file.
 
 ### More Installation Methods
 

pkg/strvals/parser.go

@@ -93,7 +93,7 @@ func runeSet(r []rune) map[rune]bool {
 }
 
 func (t *parser) key(data map[string]interface{}) error {
-	stop := runeSet([]rune{'=', ',', '.'})
+	stop := runeSet([]rune{'=', '[', ',', '.'})
 	for {
 		switch k, last, err := runesUntil(t.sc, stop); {
 		case err != nil:
@@ -103,6 +103,23 @@ func (t *parser) key(data map[string]interface{}) error {
 			return fmt.Errorf("key %q has no value", string(k))
 			//set(data, string(k), "")
 			//return err
+		case last == '[':
+			// We are in a list index context, so we need to set an index.
+			i, err := t.keyIndex()
+			if err != nil {
+				return fmt.Errorf("error parsing index: %s", err)
+			}
+			kk := string(k)
+			// Find or create target list
+			list := []interface{}{}
+			if _, ok := data[kk]; ok {
+				list = data[kk].([]interface{})
+			}
+
+			// Now we need to get the value after the ].
+			list, err = t.listItem(list, i)
+			set(data, kk, list)
+			return err
 		case last == '=':
 			//End of key. Consume =, Get value.
 			// FIXME: Get value list first
@@ -152,6 +169,71 @@ func set(data map[string]interface{}, key string, val interface{}) {
 	data[key] = val
 }
 
+func setIndex(list []interface{}, index int, val interface{}) []interface{} {
+	if len(list) <= index {
+		newlist := make([]interface{}, index+1)
+		copy(newlist, list)
+		list = newlist
+	}
+	list[index] = val
+	return list
+}
+
+func (t *parser) keyIndex() (int, error) {
+	// First, get the key.
+	stop := runeSet([]rune{']'})
+	v, _, err := runesUntil(t.sc, stop)
+	if err != nil {
+		return 0, err
+	}
+	// v should be the index
+	return strconv.Atoi(string(v))
+
+}
+func (t *parser) listItem(list []interface{}, i int) ([]interface{}, error) {
+	stop := runeSet([]rune{'[', '.', '='})
+	switch k, last, err := runesUntil(t.sc, stop); {
+	case len(k) > 0:
+		return list, fmt.Errorf("unexpected data at end of array index: %q", k)
+	case err != nil:
+		return list, err
+	case last == '=':
+		vl, e := t.valList()
+		switch e {
+		case nil:
+			return setIndex(list, i, vl), nil
+		case io.EOF:
+			return setIndex(list, i, ""), err
+		case ErrNotList:
+			v, e := t.val()
+			return setIndex(list, i, typedVal(v)), e
+		default:
+			return list, e
+		}
+	case last == '[':
+		// now we have a nested list. Read the index and handle.
+		i, err := t.keyIndex()
+		if err != nil {
+			return list, fmt.Errorf("error parsing index: %s", err)
+		}
+		// Now we need to get the value after the ].
+		list2, err := t.listItem(list, i)
+		return setIndex(list, i, list2), err
+	case last == '.':
+		// We have a nested object. Send to t.key
+		inner := map[string]interface{}{}
+		if len(list) > i {
+			inner = list[i].(map[string]interface{})
+		}
+
+		// Recurse
+		e := t.key(inner)
+		return setIndex(list, i, inner), e
+	default:
+		return nil, fmt.Errorf("parse error: unexpected token %v", last)
+	}
+}
+
 func (t *parser) val() ([]rune, error) {
 	stop := runeSet([]rune{','})
 	v, _, err := runesUntil(t.sc, stop)

pkg/strvals/parser_test.go

@@ -21,6 +21,49 @@ import (
 	"github.com/ghodss/yaml"
 )
 
+func TestSetIndex(t *testing.T) {
+	tests := []struct {
+		name    string
+		initial []interface{}
+		expect  []interface{}
+		add     int
+		val     int
+	}{
+		{
+			name:    "short",
+			initial: []interface{}{0, 1},
+			expect:  []interface{}{0, 1, 2},
+			add:     2,
+			val:     2,
+		},
+		{
+			name:    "equal",
+			initial: []interface{}{0, 1},
+			expect:  []interface{}{0, 2},
+			add:     1,
+			val:     2,
+		},
+		{
+			name:    "long",
+			initial: []interface{}{0, 1, 2, 3, 4, 5},
+			expect:  []interface{}{0, 1, 2, 4, 4, 5},
+			add:     3,
+			val:     4,
+		},
+	}
+
+	for _, tt := range tests {
+		got := setIndex(tt.initial, tt.add, tt.val)
+		if len(got) != len(tt.expect) {
+			t.Fatalf("%s: Expected length %d, got %d", tt.name, len(tt.expect), len(got))
+		}
+
+		if gg := got[tt.add].(int); gg != tt.val {
+			t.Errorf("%s, Expected value %d, got %d", tt.name, tt.val, gg)
+		}
+	}
+}
+
 func TestParseSet(t *testing.T) {
 	tests := []struct {
 		str    string
@@ -155,6 +198,59 @@ func TestParseSet(t *testing.T) {
 			str: "name1={1021,902",
 			err: true,
 		},
+		// List support
+		{
+			str:    "list[0]=foo",
+			expect: map[string]interface{}{"list": []string{"foo"}},
+		},
+		{
+			str: "list[0].foo=bar",
+			expect: map[string]interface{}{
+				"list": []interface{}{
+					map[string]interface{}{"foo": "bar"},
+				},
+			},
+		},
+		{
+			str: "list[0].foo=bar,list[0].hello=world",
+			expect: map[string]interface{}{
+				"list": []interface{}{
+					map[string]interface{}{"foo": "bar", "hello": "world"},
+				},
+			},
+		},
+		{
+			str:    "list[0]=foo,list[1]=bar",
+			expect: map[string]interface{}{"list": []string{"foo", "bar"}},
+		},
+		{
+			str:    "list[0]=foo,list[1]=bar,",
+			expect: map[string]interface{}{"list": []string{"foo", "bar"}},
+		},
+		{
+			str:    "list[0]=foo,list[3]=bar",
+			expect: map[string]interface{}{"list": []interface{}{"foo", nil, nil, "bar"}},
+		},
+		{
+			str: "illegal[0]name.foo=bar",
+			err: true,
+		},
+		{
+			str:    "noval[0]",
+			expect: map[string]interface{}{"noval": []interface{}{}},
+		},
+		{
+			str:    "noval[0]=",
+			expect: map[string]interface{}{"noval": []interface{}{""}},
+		},
+		{
+			str:    "nested[0][0]=1",
+			expect: map[string]interface{}{"nested": []interface{}{[]interface{}{1}}},
+		},
+		{
+			str:    "nested[1][1]=1",
+			expect: map[string]interface{}{"nested": []interface{}{nil, []interface{}{nil, 1}}},
+		},
 	}
 
 	for _, tt := range tests {