Cast interpolated values

Signed-off-by: Daniel Nephin <dnephin@docker.com>

cli/compose/interpolation/interpolation.go

@@ -3,6 +3,8 @@ package interpolation
 import (
 	"os"
 
+	"strings"
+
 	"github.com/docker/cli/cli/compose/template"
 	"github.com/pkg/errors"
 )
@@ -13,6 +15,8 @@ type Options struct {
 	SectionName string
 	// LookupValue from a key
 	LookupValue LookupValue
+	// TypeCastMapping maps key paths to functions to cast to a type
+	TypeCastMapping map[Path]Cast
 }
 
 // LookupValue is a function which maps from variable names to values.
@@ -21,6 +25,9 @@ type Options struct {
 // and the absence of a value.
 type LookupValue func(key string) (string, bool)
 
+// Cast a value to a new type, or return an error if the value can't be cast
+type Cast func(value string) (interface{}, error)
+
 // Interpolate replaces variables in a string with the values from a mapping
 func Interpolate(config map[string]interface{}, opts Options) (map[string]interface{}, error) {
 	out := map[string]interface{}{}
@@ -28,6 +35,9 @@ func Interpolate(config map[string]interface{}, opts Options) (map[string]interf
 	if opts.LookupValue == nil {
 		opts.LookupValue = os.LookupEnv
 	}
+	if opts.TypeCastMapping == nil {
+		opts.TypeCastMapping = make(map[Path]Cast)
+	}
 
 	for key, item := range config {
 		if item == nil {
@@ -38,7 +48,7 @@ func Interpolate(config map[string]interface{}, opts Options) (map[string]interf
 		if !ok {
 			return nil, errors.Errorf("Invalid type for %s : %T instead of %T", key, item, out)
 		}
-		interpolatedItem, err := interpolateSectionItem(key, mapItem, opts)
+		interpolatedItem, err := interpolateSectionItem(NewPath(key), mapItem, opts)
 		if err != nil {
 			return nil, err
 		}
@@ -49,23 +59,23 @@ func Interpolate(config map[string]interface{}, opts Options) (map[string]interf
 }
 
 func interpolateSectionItem(
-	sectionkey string,
+	path Path,
 	item map[string]interface{},
 	opts Options,
 ) (map[string]interface{}, error) {
 	out := map[string]interface{}{}
 
 	for key, value := range item {
-		interpolatedValue, err := recursiveInterpolate(value, opts)
+		interpolatedValue, err := recursiveInterpolate(value, path.Next(key), opts)
 		switch err := err.(type) {
 		case nil:
 		case *template.InvalidTemplateError:
 			return nil, errors.Errorf(
 				"Invalid interpolation format for %#v option in %s %#v: %#v. You may need to escape any $ with another $.",
-				key, opts.SectionName, sectionkey, err.Template,
+				key, opts.SectionName, path.root(), err.Template,
 			)
 		default:
-			return nil, errors.Wrapf(err, "error while interpolating %s in %s %s", key, opts.SectionName, sectionkey)
+			return nil, errors.Wrapf(err, "error while interpolating %s in %s %s", key, opts.SectionName, path.root())
 		}
 		out[key] = interpolatedValue
 	}
@@ -73,16 +83,24 @@ func interpolateSectionItem(
 	return out, nil
 }
 
-func recursiveInterpolate(value interface{}, opts Options) (interface{}, error) {
+func recursiveInterpolate(value interface{}, path Path, opts Options) (interface{}, error) {
 	switch value := value.(type) {
 
 	case string:
-		return template.Substitute(value, template.Mapping(opts.LookupValue))
+		newValue, err := template.Substitute(value, template.Mapping(opts.LookupValue))
+		if err != nil || newValue == value {
+			return value, err
+		}
+		caster, ok := opts.getCasterForPath(path)
+		if !ok {
+			return newValue, nil
+		}
+		return caster(newValue)
 
 	case map[string]interface{}:
 		out := map[string]interface{}{}
 		for key, elem := range value {
-			interpolatedElem, err := recursiveInterpolate(elem, opts)
+			interpolatedElem, err := recursiveInterpolate(elem, path.Next(key), opts)
 			if err != nil {
 				return nil, err
 			}
@@ -93,7 +111,7 @@ func recursiveInterpolate(value interface{}, opts Options) (interface{}, error)
 	case []interface{}:
 		out := make([]interface{}, len(value))
 		for i, elem := range value {
-			interpolatedElem, err := recursiveInterpolate(elem, opts)
+			interpolatedElem, err := recursiveInterpolate(elem, path, opts)
 			if err != nil {
 				return nil, err
 			}
@@ -106,3 +124,62 @@ func recursiveInterpolate(value interface{}, opts Options) (interface{}, error)
 
 	}
 }
+
+const pathSeparator = "."
+
+// PathMatchAll is a token used as part of a Path to match any key at that level
+// in the nested structure
+const PathMatchAll = "*"
+
+// Path is a dotted path of keys to a value in a nested mapping structure. A *
+// section in a path will match any key in the mapping structure.
+type Path string
+
+// NewPath returns a new Path
+func NewPath(items ...string) Path {
+	return Path(strings.Join(items, pathSeparator))
+}
+
+// Next returns a new path by append part to the current path
+func (p Path) Next(part string) Path {
+	return Path(string(p) + pathSeparator + part)
+}
+
+func (p Path) root() string {
+	parts := p.parts()
+	if len(parts) == 0 {
+		return ""
+	}
+	return parts[0]
+}
+
+func (p Path) parts() []string {
+	return strings.Split(string(p), pathSeparator)
+}
+
+func (p Path) matches(pattern Path) bool {
+	patternParts := pattern.parts()
+	parts := p.parts()
+
+	if len(patternParts) != len(parts) {
+		return false
+	}
+	for index, part := range parts {
+		switch patternParts[index] {
+		case PathMatchAll, part:
+			continue
+		default:
+			return false
+		}
+	}
+	return true
+}
+
+func (o Options) getCasterForPath(path Path) (Cast, bool) {
+	for pattern, caster := range o.TypeCastMapping {
+		if path.matches(pattern) {
+			return caster, true
+		}
+	}
+	return nil, false
+}

cli/compose/interpolation/interpolation_test.go

@@ -3,6 +3,8 @@ package interpolation
 import (
 	"testing"
 
+	"strconv"
+
 	"github.com/gotestyourself/gotestyourself/env"
 	"github.com/stretchr/testify/assert"
 )
@@ -10,6 +12,7 @@ import (
 var defaults = map[string]string{
 	"USER":  "jenny",
 	"FOO":   "bar",
+	"count": "5",
 }
 
 func defaultMapping(name string) (string, bool) {
@@ -80,3 +83,70 @@ func TestInterpolateWithDefaults(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, expected, result)
 }
+
+func TestInterpolateWithCast(t *testing.T) {
+	config := map[string]interface{}{
+		"foo": map[string]interface{}{
+			"replicas": "$count",
+		},
+	}
+	toInt := func(value string) (interface{}, error) {
+		return strconv.Atoi(value)
+	}
+	result, err := Interpolate(config, Options{
+		LookupValue:     defaultMapping,
+		TypeCastMapping: map[Path]Cast{NewPath("*", "replicas"): toInt},
+	})
+	assert.NoError(t, err)
+	expected := map[string]interface{}{
+		"foo": map[string]interface{}{
+			"replicas": 5,
+		},
+	}
+	assert.Equal(t, expected, result)
+}
+
+func TestPathMatches(t *testing.T) {
+	var testcases = []struct {
+		doc      string
+		path     Path
+		pattern  Path
+		expected bool
+	}{
+		{
+			doc:     "pattern too short",
+			path:    NewPath("one", "two", "three"),
+			pattern: NewPath("one", "two"),
+		},
+		{
+			doc:     "pattern too long",
+			path:    NewPath("one", "two"),
+			pattern: NewPath("one", "two", "three"),
+		},
+		{
+			doc:     "pattern mismatch",
+			path:    NewPath("one", "three", "two"),
+			pattern: NewPath("one", "two", "three"),
+		},
+		{
+			doc:     "pattern mismatch with match-all part",
+			path:    NewPath("one", "three", "two"),
+			pattern: NewPath(PathMatchAll, "two", "three"),
+		},
+		{
+			doc:      "pattern match with match-all part",
+			path:     NewPath("one", "two", "three"),
+			pattern:  NewPath("one", "*", "three"),
+			expected: true,
+		},
+		{
+			doc:      "pattern match",
+			path:     NewPath("one", "two", "three"),
+			pattern:  NewPath("one", "two", "three"),
+			expected: true,
+		},
+	}
+	for _, testcase := range testcases {
+		assert.Equal(t, testcase.expected, testcase.path.matches(testcase.pattern))
+	}
+}

cli/compose/loader/interpolate.go

@@ -0,0 +1,95 @@
+package loader
+
+import (
+	"strconv"
+	"strings"
+
+	interp "github.com/docker/cli/cli/compose/interpolation"
+	"github.com/pkg/errors"
+)
+
+var interpolateTypeCastMapping = map[string]map[interp.Path]interp.Cast{
+	"services": {
+		iPath("configs", "mode"):                              toInt,
+		iPath("secrets", "mode"):                              toInt,
+		iPath("healthcheck", "retries"):                       toInt,
+		iPath("healthcheck", "disable"):                       toBoolean,
+		iPath("deploy", "replicas"):                           toInt,
+		iPath("deploy", "update_config", "parallelism:"):      toInt,
+		iPath("deploy", "update_config", "max_failure_ratio"): toFloat,
+		iPath("deploy", "restart_policy", "max_attempts"):     toInt,
+		iPath("ports", "target"):                              toInt,
+		iPath("ports", "published"):                           toInt,
+		iPath("ulimits", interp.PathMatchAll):                 toInt,
+		iPath("ulimits", interp.PathMatchAll, "hard"):         toInt,
+		iPath("ulimits", interp.PathMatchAll, "soft"):         toInt,
+		iPath("privileged"):                                   toBoolean,
+		iPath("read_only"):                                    toBoolean,
+		iPath("stdin_open"):                                   toBoolean,
+		iPath("tty"):                                          toBoolean,
+		iPath("volumes", "read_only"):                         toBoolean,
+		iPath("volumes", "volume", "nocopy"):                  toBoolean,
+	},
+	"networks": {
+		iPath("external"):   toBoolean,
+		iPath("internal"):   toBoolean,
+		iPath("attachable"): toBoolean,
+	},
+	"volumes": {
+		iPath("external"): toBoolean,
+	},
+	"secrets": {
+		iPath("external"): toBoolean,
+	},
+	"configs": {
+		iPath("external"): toBoolean,
+	},
+}
+
+func iPath(parts ...string) interp.Path {
+	return interp.NewPath(append([]string{interp.PathMatchAll}, parts...)...)
+}
+
+func toInt(value string) (interface{}, error) {
+	return strconv.Atoi(value)
+}
+
+func toFloat(value string) (interface{}, error) {
+	return strconv.ParseFloat(value, 64)
+}
+
+// should match http://yaml.org/type/bool.html
+func toBoolean(value string) (interface{}, error) {
+	switch strings.ToLower(value) {
+	case "y", "yes", "true", "on":
+		return true, nil
+	case "n", "no", "false", "off":
+		return false, nil
+	default:
+		return nil, errors.Errorf("invalid boolean: %s", value)
+	}
+}
+
+func interpolateConfig(configDict map[string]interface{}, lookupEnv interp.LookupValue) (map[string]map[string]interface{}, error) {
+	config := make(map[string]map[string]interface{})
+
+	for _, key := range []string{"services", "networks", "volumes", "secrets", "configs"} {
+		section, ok := configDict[key]
+		if !ok {
+			config[key] = make(map[string]interface{})
+			continue
+		}
+		var err error
+		config[key], err = interp.Interpolate(
+			section.(map[string]interface{}),
+			interp.Options{
+				SectionName:     key,
+				LookupValue:     lookupEnv,
+				TypeCastMapping: interpolateTypeCastMapping[key],
+			})
+		if err != nil {
+			return nil, err
+		}
+	}
+	return config, nil
+}

cli/compose/loader/loader.go

@@ -8,7 +8,6 @@ import (
 	"sort"
 	"strings"
 
-	"github.com/docker/cli/cli/compose/interpolation"
 	"github.com/docker/cli/cli/compose/schema"
 	"github.com/docker/cli/cli/compose/template"
 	"github.com/docker/cli/cli/compose/types"
@@ -51,14 +50,13 @@ func Load(configDetails types.ConfigDetails) (*types.Config, error) {
 
 	configDict := getConfigDict(configDetails)
 
-	if services, ok := configDict["services"]; ok {
-		if servicesDict, ok := services.(map[string]interface{}); ok {
-			forbidden := getProperties(servicesDict, types.ForbiddenProperties)
+	if err := validateForbidden(configDict); err != nil {
+		return nil, err
+	}
 
-			if len(forbidden) > 0 {
-				return nil, &ForbiddenPropertiesError{Properties: forbidden}
-			}
-		}
+	config, err := interpolateConfig(configDict, configDetails.LookupEnv)
+	if err != nil {
+		return nil, err
 	}
 
 	if err := schema.Validate(configDict, schema.Version(configDict)); err != nil {
@@ -66,12 +64,6 @@ func Load(configDetails types.ConfigDetails) (*types.Config, error) {
 	}
 
 	cfg := types.Config{}
-
-	config, err := interpolateConfig(configDict, configDetails.LookupEnv)
-	if err != nil {
-		return nil, err
-	}
-
 	cfg.Services, err = LoadServices(config["services"], configDetails.WorkingDir, configDetails.LookupEnv)
 	if err != nil {
 		return nil, err
@@ -96,22 +88,16 @@ func Load(configDetails types.ConfigDetails) (*types.Config, error) {
 	return &cfg, err
 }
 
-func interpolateConfig(configDict map[string]interface{}, lookupEnv template.Mapping) (map[string]map[string]interface{}, error) {
-	config := make(map[string]map[string]interface{})
-
-	for _, key := range []string{"services", "networks", "volumes", "secrets", "configs"} {
-		section, ok := configDict[key]
+func validateForbidden(configDict map[string]interface{}) error {
+	servicesDict, ok := configDict["services"].(map[string]interface{})
 	if !ok {
-			config[key] = make(map[string]interface{})
-			continue
+		return nil
 	}
-		var err error
-		config[key], err = interpolation.Interpolate(section.(map[string]interface{}), key, lookupEnv)
-		if err != nil {
-			return nil, err
+	forbidden := getProperties(servicesDict, types.ForbiddenProperties)
+	if len(forbidden) > 0 {
+		return &ForbiddenPropertiesError{Properties: forbidden}
 	}
-	}
-	return config, nil
+	return nil
 }
 
 // GetUnsupportedProperties returns the list of any unsupported properties that are

cli/compose/loader/loader_test.go

@@ -465,7 +465,7 @@ services:
 	assert.Contains(t, err.Error(), "services.dict-env.environment must be a mapping")
 }
 
-func TestEnvironmentInterpolation(t *testing.T) {
+func TestLoadWithEnvironmentInterpolation(t *testing.T) {
 	home := "/home/foo"
 	config, err := loadYAMLWithEnv(`
 version: "3"
@@ -502,6 +502,75 @@ volumes:
 	assert.Equal(t, home, config.Volumes["test"].Driver)
 }
 
+func TestLoadWithInterpolationCastFull(t *testing.T) {
+	dict, err := ParseYAML([]byte(`
+version: "3.4"
+services:
+  web:
+    configs:
+      - source: appconfig
+        mode: $theint
+    secrets:
+      - source: super
+        mode: $theint
+    healthcheck:
+      retries: ${theint}
+      disable: $thebool
+    deploy:
+      replicas: $theint
+      update_config:
+        parallelism: $theint
+        max_failure_ratio: $thefloat
+      restart_policy:
+        max_attempts: $theint
+    ports:
+      - $theint
+      - "34567"
+      - target: $theint
+        published: $theint
+    ulimits:
+      - $theint
+      - hard: $theint
+        soft: $theint
+    privileged: $thebool
+    read_only: $thebool
+    stdin_open: ${thebool}
+    tty: $thebool
+    volumes:
+      - source: data
+        read_only: $thebool
+        volume:
+          nocopy: $thebool
+
+configs:
+  appconfig:
+    external: $thebool
+secrets:
+  super:
+    external: $thebool
+volumes:
+  data:
+    external: $thebool
+networks:
+  front:
+    external: $thebool
+    internal: $thebool
+    attachable: $thebool
+
+`))
+	require.NoError(t, err)
+	env := map[string]string{
+		"theint":   "555",
+		"thefloat": "3.14",
+		"thebool":  "true",
+	}
+
+	config, err := Load(buildConfigDetails(dict, env))
+	require.NoError(t, err)
+	expected := &types.Config{}
+	assert.Equal(t, expected, config)
+}
+
 func TestUnsupportedProperties(t *testing.T) {
 	dict, err := ParseYAML([]byte(`
 version: "3"