Allow to escape newlines and tabs in --set

Fixes #3251

docs/using_helm.md

@@ -300,6 +300,12 @@ nodeSelector:
   kubernetes.io/role: master
 ```
 
+Other escape sequences are supported:
+- ```\\n```
+- ```\\r```
+- ```\\t```
+- any unsupported sequence will keep the following character
+
 Deeply nested data structures 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.

pkg/strvals/parser.go

@@ -286,6 +286,15 @@ func runesUntil(in io.RuneReader, stop map[rune]bool) ([]rune, rune, error) {
 			if e != nil {
 				return v, next, e
 			}
+			switch next {
+			case 'n':
+				next = '\n'
+			case 'r':
+				next = '\r'
+			case 't':
+				next = '\t'
+			}
+
 			v = append(v, next)
 		default:
 			v = append(v, r)

pkg/strvals/parser_test.go

@@ -255,6 +255,10 @@ func TestParseSet(t *testing.T) {
 			str:    "nested[1][1]=1",
 			expect: map[string]interface{}{"nested": []interface{}{nil, []interface{}{nil, 1}}},
 		},
+		{
+			str:    "escapes=hello\\n\\tworld",
+			expect: map[string]interface{}{"escapes": "hello\n\tworld"},
+		},
 	}
 
 	for _, tt := range tests {