fix escaping and expose expansion with custom values

expandenv.go

@@ -8,33 +8,48 @@ import (
 	"strings"
 )
 
+func environMap() map[string]string {
+	result := map[string]string{}
+	for _, entry := range os.Environ() {
+		splitted := strings.SplitN(entry, "=", 2)
+		key := splitted[0]
+		value := splitted[1]
+		result[key] = value
+	}
+	return result
+}
+
 func ExpandEnv(input interface{}) (interface{}, error) {
+	return Expand(input, environMap())
+}
+
+func Expand(input interface{}, values map[string]string) (interface{}, error) {
 	singleRegex := regexp.MustCompile(`^\$\{[^\}]+\}$`)
-	detectRegex := regexp.MustCompile(`(?:^|[^\\])\$\{[^\}]+\}`)
+	detectRegex := regexp.MustCompile(`\\?\$\{[^\}]+\}`)
 	var recursion func(current interface{}) (interface{}, []error)
 	recursion = func(current interface{}) (interface{}, []error) {
 		if current, ok := current.(string); ok {
 			p := singleRegex.FindStringSubmatch(current)
 			if p != nil {
-				expanded, err := expandEnvValue(current)
+				expanded, err := expandEnvValue(current, values)
 				if err != nil {
 					return current, []error{err}
 				}
 				return expanded, nil
 			}
 			errs := []error{}
 			expanded := detectRegex.ReplaceAllStringFunc(current, func(str string) string {
-				index := strings.IndexAny(str, "$")
-				prefix := str[:index]
-				value := str[index:]
+				if strings.HasPrefix(str, "\\") {
+					return str[1:]
+				}
 
-				expanded, err := expandEnvValue(value)
+				expanded, err := expandEnvValue(str, values)
 				if err != nil {
 					errs = append(errs, err)
 					return str
 				}
 
-				return fmt.Sprintf("%s%v", prefix, expanded)
+				return fmt.Sprintf("%v", expanded)
 			})
 			return expanded, errs
 		}
@@ -75,7 +90,7 @@ func ExpandEnv(input interface{}) (interface{}, error) {
 	return output, nil
 }
 
-func expandEnvValue(str string) (interface{}, error) {
+func expandEnvValue(str string, values map[string]string) (interface{}, error) {
 	regex := regexp.MustCompile(`^\$\{(?P<name>[^:]+)(?P<hasFormat>:(?P<format>number|boolean|string))?(?P<hasFallback>:-(?P<fallback>.*))?\}$`)
 	p := regex.FindStringSubmatch(str)
 	if p == nil {
@@ -85,7 +100,7 @@ func expandEnvValue(str string) (interface{}, error) {
 	format := p[regex.SubexpIndex("format")]
 	hasFallback := p[regex.SubexpIndex("hasFallback")] != ""
 	fallback := p[regex.SubexpIndex("fallback")]
-	value, ok := os.LookupEnv(name)
+	value, ok := values[name]
 	if !ok {
 		if !hasFallback {
 			return nil, fmt.Errorf("environment variable %s is missing", name)

expandenv_test.go

@@ -10,13 +10,15 @@ import (
 	"gopkg.in/yaml.v3"
 )
 
-func TestExpandEnv(t *testing.T) {
-	os.Setenv("ENV_A", "a")
-	os.Setenv("ENV_B", "b")
-	os.Setenv("ENV_42", "42")
-	os.Setenv("ENV_42_5", "42.5")
-	os.Setenv("ENV_YES", "yes")
-	os.Setenv("ENV_MULTI_LINE", "line1\nline2")
+func TestExpand(t *testing.T) {
+	values := map[string]string{
+		"ENV_A":          "a",
+		"ENV_B":          "b",
+		"ENV_42":         "42",
+		"ENV_42_5":       "42.5",
+		"ENV_YES":        "yes",
+		"ENV_MULTI_LINE": "line1\nline2",
+	}
 
 	testCases := []struct {
 		input  interface{}
@@ -71,12 +73,12 @@ func TestExpandEnv(t *testing.T) {
 		},
 		{
 			input:  "\\${ENV_A}",
-			output: "\\${ENV_A}",
+			output: "${ENV_A}",
 			label:  "variabled-escacped-string",
 		},
 		{
 			input:  "prefix \\${ENV_A} suffix",
-			output: "prefix \\${ENV_A} suffix",
+			output: "prefix ${ENV_A} suffix",
 			label:  "variabled-escacped-string-2",
 		},
 		{
@@ -134,7 +136,7 @@ func TestExpandEnv(t *testing.T) {
 	}
 
 	for _, testCase := range testCases {
-		output, err := ExpandEnv(testCase.input)
+		output, err := Expand(testCase.input, values)
 		if testCase.error == nil {
 			assert.NoError(t, err, testCase.label)
 		} else {
@@ -144,9 +146,44 @@ func TestExpandEnv(t *testing.T) {
 	}
 }
 
-func TestExpandEnvWithYaml(t *testing.T) {
+func TestExpandEnv(t *testing.T) {
 	os.Setenv("ENV_A", "a")
-	os.Setenv("ENV_MULTI_LINE", "line1\nline2")
+	os.Setenv("ENV_B", "b")
+
+	testCases := []struct {
+		input  interface{}
+		output interface{}
+		label  string
+		error  error
+	}{
+		{
+			input:  "${ENV_A}",
+			output: "a",
+			label:  "variabled-string",
+		},
+		{
+			input:  "prefix ${ENV_B} suffix",
+			output: "prefix b suffix",
+			label:  "variabled-string-2",
+		},
+	}
+
+	for _, testCase := range testCases {
+		output, err := ExpandEnv(testCase.input)
+		if testCase.error == nil {
+			assert.NoError(t, err, testCase.label)
+		} else {
+			assert.EqualError(t, err, testCase.error.Error(), testCase.label)
+		}
+		assert.Equal(t, testCase.output, output, testCase.label)
+	}
+}
+
+func TestExpandWithYaml(t *testing.T) {
+	values := map[string]string{
+		"ENV_A":          "a",
+		"ENV_MULTI_LINE": "line1\nline2",
+	}
 
 	yamlBytes := []byte(`
 a: ${ENV_A}
@@ -157,11 +194,12 @@ c:
 d: ${ENV_MULTI_LINE}
 e: ${ENV_UNKNOWN}
 f: \${ENV_ESCAPED}
+g: \\${ENV_ESCAPED}
 `)
 	var yamlRaw interface{}
 	err := yaml.Unmarshal(yamlBytes, &yamlRaw)
 	assert.NoError(t, err)
-	yamlRaw, err = ExpandEnv(yamlRaw)
+	yamlRaw, err = Expand(yamlRaw, values)
 	assert.EqualError(t, err, "environment variable ENV_UNKNOWN is missing")
 	yamlBytes, err = yaml.Marshal(yamlRaw)
 	assert.NoError(t, err)
@@ -174,6 +212,7 @@ d: |-
     line1
     line2
 e: ${ENV_UNKNOWN}
-f: \${ENV_ESCAPED}
+f: ${ENV_ESCAPED}
+g: \${ENV_ESCAPED}
 `, string(yamlBytes))
 }