Use compose-spec parser

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

vendor/github.com/compose-spec/compose-go/interpolation/interpolation.go

@@ -0,0 +1,177 @@
+/*
+   Copyright 2020 The Compose Specification Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package interpolation
+
+import (
+	"os"
+	"strings"
+
+	"github.com/compose-spec/compose-go/template"
+	"github.com/pkg/errors"
+)
+
+// Options supported by Interpolate
+type Options struct {
+	// LookupValue from a key
+	LookupValue LookupValue
+	// TypeCastMapping maps key paths to functions to cast to a type
+	TypeCastMapping map[Path]Cast
+	// Substitution function to use
+	Substitute func(string, template.Mapping) (string, error)
+}
+
+// LookupValue is a function which maps from variable names to values.
+// Returns the value as a string and a bool indicating whether
+// the value is present, to distinguish between an empty string
+// 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) {
+	if opts.LookupValue == nil {
+		opts.LookupValue = os.LookupEnv
+	}
+	if opts.TypeCastMapping == nil {
+		opts.TypeCastMapping = make(map[Path]Cast)
+	}
+	if opts.Substitute == nil {
+		opts.Substitute = template.Substitute
+	}
+
+	out := map[string]interface{}{}
+
+	for key, value := range config {
+		interpolatedValue, err := recursiveInterpolate(value, NewPath(key), opts)
+		if err != nil {
+			return out, err
+		}
+		out[key] = interpolatedValue
+	}
+
+	return out, nil
+}
+
+func recursiveInterpolate(value interface{}, path Path, opts Options) (interface{}, error) {
+	switch value := value.(type) {
+	case string:
+		newValue, err := opts.Substitute(value, template.Mapping(opts.LookupValue))
+		if err != nil || newValue == value {
+			return value, newPathError(path, err)
+		}
+		caster, ok := opts.getCasterForPath(path)
+		if !ok {
+			return newValue, nil
+		}
+		casted, err := caster(newValue)
+		return casted, newPathError(path, errors.Wrap(err, "failed to cast to expected type"))
+
+	case map[string]interface{}:
+		out := map[string]interface{}{}
+		for key, elem := range value {
+			interpolatedElem, err := recursiveInterpolate(elem, path.Next(key), opts)
+			if err != nil {
+				return nil, err
+			}
+			out[key] = interpolatedElem
+		}
+		return out, nil
+
+	case []interface{}:
+		out := make([]interface{}, len(value))
+		for i, elem := range value {
+			interpolatedElem, err := recursiveInterpolate(elem, path.Next(PathMatchList), opts)
+			if err != nil {
+				return nil, err
+			}
+			out[i] = interpolatedElem
+		}
+		return out, nil
+
+	default:
+		return value, nil
+	}
+}
+
+func newPathError(path Path, err error) error {
+	switch err := err.(type) {
+	case nil:
+		return nil
+	case *template.InvalidTemplateError:
+		return errors.Errorf(
+			"invalid interpolation format for %s: %#v. You may need to escape any $ with another $.",
+			path, err.Template)
+	default:
+		return errors.Wrapf(err, "error while interpolating %s", path)
+	}
+}
+
+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 = "*"
+
+// PathMatchList is a token used as part of a Path to match items in a list
+const PathMatchList = "[]"
+
+// 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) 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
+}