Fix default values on variables interpolation

Signed-off-by: Ulysses Souza <[email protected]>

Author: ulyssessouza

interpolation/interpolation_test.go

@@ -17,9 +17,8 @@
 package interpolation
 
 import (
-	"testing"
-
 	"strconv"
+	"testing"
 
 	"gotest.tools/v3/assert"
 	is "gotest.tools/v3/assert/cmp"
@@ -95,6 +94,75 @@ func TestInterpolateWithDefaults(t *testing.T) {
 	assert.Check(t, is.DeepEqual(expected, result))
 }
 
+func TestValidUnexistentInterpolation(t *testing.T) {
+	var testcases = []struct {
+		test     string
+		expected string
+	}{
+		{test: "{{{ ${FOO:-foo_} }}}", expected: "{{{ foo_ }}}"},
+		{test: "{{{ ${FOO:-foo-bar-value} }}}", expected: "{{{ foo-bar-value }}}"},
+		{test: "{{{ ${FOO:-foo} ${BAR:-DEFAULT_VALUE} }}}", expected: "{{{ foo DEFAULT_VALUE }}}"},
+		{test: "{{{ ${BAR} }}}", expected: "{{{  }}}"},
+		{test: "${FOO:-baz} }}}", expected: "baz }}}"},
+		{test: "${FOO-baz} }}}", expected: "baz }}}"},
+	}
+
+	getServiceConfig := func(val string) map[string]interface{} {
+		return map[string]interface{}{
+			"myservice": map[string]interface{}{
+				"environment": map[string]interface{}{
+					"TESTVAR": val,
+				},
+			},
+		}
+	}
+
+	for _, testcase := range testcases {
+		result, err := Interpolate(getServiceConfig(testcase.test), Options{})
+		assert.NilError(t, err)
+		assert.Check(t, is.DeepEqual(getServiceConfig(testcase.expected), result))
+	}
+}
+
+func TestValidExistentInterpolation(t *testing.T) {
+	var testcases = []struct {
+		test     string
+		expected string
+	}{
+		// Only FOO is set
+		{test: "{{{ ${FOO:-foo_} }}}", expected: "{{{ bar }}}"},
+		{test: "{{{ ${FOO:-foo-bar-value} }}}", expected: "{{{ bar }}}"},
+		{test: "{{{ ${FOO:-foo} ${BAR:-DEFAULT_VALUE} }}}", expected: "{{{ bar DEFAULT_VALUE }}}"},
+		{test: "{{{ ${BAR} }}}", expected: "{{{  }}}"},
+		{test: "${FOO:-baz} }}}", expected: "bar }}}"},
+		{test: "${FOO-baz} }}}", expected: "bar }}}"},
+
+		// Both FOO and USER are set
+		{test: "{{{ ${FOO:-foo_} }}}", expected: "{{{ bar }}}"},
+		{test: "{{{ ${FOO:-foo-bar-value} }}}", expected: "{{{ bar }}}"},
+		{test: "{{{ ${FOO:-foo} ${USER:-bar} }}}", expected: "{{{ bar jenny }}}"},
+		{test: "{{{ ${USER} }}}", expected: "{{{ jenny }}}"},
+		{test: "${FOO:-baz} }}}", expected: "bar }}}"},
+		{test: "${FOO-baz} }}}", expected: "bar }}}"},
+	}
+
+	getServiceConfig := func(val string) map[string]interface{} {
+		return map[string]interface{}{
+			"myservice": map[string]interface{}{
+				"environment": map[string]interface{}{
+					"TESTVAR": val,
+				},
+			},
+		}
+	}
+
+	for _, testcase := range testcases {
+		result, err := Interpolate(getServiceConfig(testcase.test), Options{LookupValue: defaultMapping})
+		assert.NilError(t, err)
+		assert.Check(t, is.DeepEqual(getServiceConfig(testcase.expected), result))
+	}
+}
+
 func TestInterpolateWithCast(t *testing.T) {
 	config := map[string]interface{}{
 		"foo": map[string]interface{}{

template/template.go

@@ -26,6 +26,7 @@ import (
 
 var delimiter = "\\$"
 var substitutionNamed = "[_a-z][_a-z0-9]*"
+
 var substitutionBraced = "[_a-z][_a-z0-9]*(?::?[-?](.*}|[^}]*))?"
 
 var patternString = fmt.Sprintf(
@@ -69,6 +70,13 @@ func SubstituteWith(template string, mapping Mapping, pattern *regexp.Regexp, su
 	}
 	var err error
 	result := pattern.ReplaceAllStringFunc(template, func(substring string) string {
+		closingBraceIndex := getFirstBraceClosingIndex(substring)
+		rest := ""
+		if closingBraceIndex > -1 {
+			rest = substring[closingBraceIndex+1:]
+			substring = substring[0 : closingBraceIndex+1]
+		}
+
 		matches := pattern.FindStringSubmatch(substring)
 		groups := matchGroups(matches, pattern)
 		if escaped := groups["escaped"]; escaped != "" {
@@ -100,7 +108,11 @@ func SubstituteWith(template string, mapping Mapping, pattern *regexp.Regexp, su
 				if !applied {
 					continue
 				}
-				return value
+				interpolatedNested, err := SubstituteWith(rest, mapping, pattern, subsFuncs...)
+				if err != nil {
+					return ""
+				}
+				return value + interpolatedNested
 			}
 		}
 
@@ -114,6 +126,23 @@ func SubstituteWith(template string, mapping Mapping, pattern *regexp.Regexp, su
 	return result, err
 }
 
+func getFirstBraceClosingIndex(s string) int {
+	openVariableBraces := 0
+	for i := 0; i < len(s); i++ {
+		if s[i] == '}' {
+			openVariableBraces--
+			if openVariableBraces == 0 {
+				return i
+			}
+		}
+		if strings.HasPrefix(s[i:], "${") {
+			openVariableBraces++
+			i++
+		}
+	}
+	return -1
+}
+
 // Substitute variables in the string with their values
 func Substitute(template string, mapping Mapping) (string, error) {
 	return SubstituteWith(template, mapping, defaultPattern)