Merge pull request #893 from adshmh/add-support-for-mandatory-variables-syntax-to-stack-deploy

add support for mandatory variables to stack deploy

cli/compose/template/template.go

@@ -7,7 +7,7 @@ import (
 )
 
 var delimiter = "\\$"
-var substitution = "[_a-z][_a-z0-9]*(?::?-[^}]+)?"
+var substitution = "[_a-z][_a-z0-9]*(?::?[-?][^}]*)?"
 
 var patternString = fmt.Sprintf(
 	"%s(?i:(?P<escaped>%s)|(?P<named>%s)|{(?P<braced>%s)}|(?P<invalid>))",
@@ -37,57 +37,78 @@ func Substitute(template string, mapping Mapping) (string, error) {
 	var err error
 	result := pattern.ReplaceAllStringFunc(template, func(substring string) string {
 		matches := pattern.FindStringSubmatch(substring)
-		groups := make(map[string]string)
+		groups := matchGroups(matches)
-		for i, name := range pattern.SubexpNames() {
+		if escaped := groups["escaped"]; escaped != "" {
-			if i != 0 {
+			return escaped
-				groups[name] = matches[i]
-			}
 		}
 
 		substitution := groups["named"]
 		if substitution == "" {
 			substitution = groups["braced"]
 		}
-		if substitution != "" {
-			// Soft default (fall back if unset or empty)
-			if strings.Contains(substitution, ":-") {
-				name, defaultValue := partition(substitution, ":-")
-				value, ok := mapping(name)
-				if !ok || value == "" {
-					return defaultValue
-				}
-				return value
-			}
 
-			// Hard default (fall back if-and-only-if empty)
+		switch {
-			if strings.Contains(substitution, "-") {
-				name, defaultValue := partition(substitution, "-")
-				value, ok := mapping(name)
-				if !ok {
-					return defaultValue
-				}
-				return value
-			}
 
-			// No default (fall back to empty string)
+		case substitution == "":
-			value, ok := mapping(substitution)
+			err = &InvalidTemplateError{Template: template}
+			return ""
+
+		// Soft default (fall back if unset or empty)
+		case strings.Contains(substitution, ":-"):
+			name, defaultValue := partition(substitution, ":-")
+			value, ok := mapping(name)
+			if !ok || value == "" {
+				return defaultValue
+			}
+			return value
+
+		// Hard default (fall back if-and-only-if empty)
+		case strings.Contains(substitution, "-"):
+			name, defaultValue := partition(substitution, "-")
+			value, ok := mapping(name)
 			if !ok {
+				return defaultValue
+			}
+			return value
+
+		case strings.Contains(substitution, ":?"):
+			name, errorMessage := partition(substitution, ":?")
+			value, ok := mapping(name)
+			if !ok || value == "" {
+				err = &InvalidTemplateError{
+					Template: fmt.Sprintf("required variable %s is missing a value: %s", name, errorMessage),
+				}
+				return ""
+			}
+			return value
+
+		case strings.Contains(substitution, "?"):
+			name, errorMessage := partition(substitution, "?")
+			value, ok := mapping(name)
+			if !ok {
+				err = &InvalidTemplateError{
+					Template: fmt.Sprintf("required variable %s is missing a value: %s", name, errorMessage),
+				}
 				return ""
 			}
 			return value
 		}
 
-		if escaped := groups["escaped"]; escaped != "" {
+		value, _ := mapping(substitution)
-			return escaped
+		return value
-		}
-
-		err = &InvalidTemplateError{Template: template}
-		return ""
 	})
 
 	return result, err
 }
 
+func matchGroups(matches []string) map[string]string {
+	groups := make(map[string]string)
+	for i, name := range pattern.SubexpNames()[1:] {
+		groups[name] = matches[i+1]
+	}
+	return groups
+}
+
 // Split the string at the first occurrence of sep, and return the part before the separator,
 // and the part after the separator.
 //

cli/compose/template/template_test.go

@@ -3,7 +3,9 @@ package template
 import (
 	"testing"
 
+	"github.com/docker/cli/internal/test/testutil"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 var defaults = map[string]string{
@@ -22,6 +24,12 @@ func TestEscaped(t *testing.T) {
 	assert.Equal(t, "${foo}", result)
 }
 
+func TestSubstituteNoMatch(t *testing.T) {
+	result, err := Substitute("foo", defaultMapping)
+	require.NoError(t, err)
+	require.Equal(t, "foo", result)
+}
+
 func TestInvalid(t *testing.T) {
 	invalidTemplates := []string{
 		"${",
@@ -81,3 +89,64 @@ func TestNonAlphanumericDefault(t *testing.T) {
 	assert.Nil(t, err)
 	assert.Equal(t, "ok /non:-alphanumeric", result)
 }
+
+func TestMandatoryVariableErrors(t *testing.T) {
+	testCases := []struct {
+		template      string
+		expectedError string
+	}{
+		{
+			template:      "not ok ${UNSET_VAR:?Mandatory Variable Unset}",
+			expectedError: "required variable UNSET_VAR is missing a value: Mandatory Variable Unset",
+		},
+		{
+			template:      "not ok ${BAR:?Mandatory Variable Empty}",
+			expectedError: "required variable BAR is missing a value: Mandatory Variable Empty",
+		},
+		{
+			template:      "not ok ${UNSET_VAR:?}",
+			expectedError: "required variable UNSET_VAR is missing a value",
+		},
+		{
+			template:      "not ok ${UNSET_VAR?Mandatory Variable Unset}",
+			expectedError: "required variable UNSET_VAR is missing a value: Mandatory Variable Unset",
+		},
+		{
+			template:      "not ok ${UNSET_VAR?}",
+			expectedError: "required variable UNSET_VAR is missing a value",
+		},
+	}
+
+	for _, tc := range testCases {
+		_, err := Substitute(tc.template, defaultMapping)
+		assert.Error(t, err)
+		assert.IsType(t, &InvalidTemplateError{}, err)
+		testutil.ErrorContains(t, err, tc.expectedError)
+	}
+}
+
+func TestDefaultsForMandatoryVariables(t *testing.T) {
+	testCases := []struct {
+		template string
+		expected string
+	}{
+		{
+			template: "ok ${FOO:?err}",
+			expected: "ok first",
+		},
+		{
+			template: "ok ${FOO?err}",
+			expected: "ok first",
+		},
+		{
+			template: "ok ${BAR?err}",
+			expected: "ok ",
+		},
+	}
+
+	for _, tc := range testCases {
+		result, err := Substitute(tc.template, defaultMapping)
+		assert.Nil(t, err)
+		assert.Equal(t, tc.expected, result)
+	}
+}