open-nomad/client/taskenv/util.go
2018-11-30 12:18:39 +01:00

132 lines
3.1 KiB
Go

package taskenv
import (
"errors"
"fmt"
"strings"
"github.com/zclconf/go-cty/cty"
)
var (
// ErrInvalidObjectPath is returned when a key cannot be converted into
// a nested object path like "foo...bar", ".foo", or "foo."
ErrInvalidObjectPath = errors.New("invalid object path")
)
type ErrKeyExists struct {
msg string
}
func NewErrKeyExists(newKey, oldKey string) *ErrKeyExists {
return &ErrKeyExists{
msg: fmt.Sprintf(
"cannot add key %q because %q already exists with a different type",
newKey, oldKey,
),
}
}
func (e *ErrKeyExists) Error() string {
return e.msg
}
// addNestedKey expands keys into their nested form:
//
// k="foo.bar", v="quux" -> {"foo": {"bar": "quux"}}
//
// Existing keys are overwritten.
//
// If the key has dots but cannot be converted to a valid nested data structure
// (eg "foo...bar", "foo.", or non-object value exists for key), an error is
// returned.
func addNestedKey(dst map[string]interface{}, k, v string) error {
// createdParent and Key capture the parent object of the first created
// object and the first created object's key respectively. The cleanup
// func deletes them to prevent side-effects when returning errors.
var createdParent map[string]interface{}
var createdKey string
cleanup := func() {
if createdParent != nil {
delete(createdParent, createdKey)
}
}
segments := strings.Split(k, ".")
for _, newKey := range segments[:len(segments)-1] {
if newKey == "" {
// String either begins with a dot (.foo) or has at
// least two consecutive dots (foo..bar); either way
// it's an invalid object path.
cleanup()
return ErrInvalidObjectPath
}
var target map[string]interface{}
if existingI, ok := dst[newKey]; ok {
existing, ok := existingI.(map[string]interface{})
if !ok {
// Existing value is not a map, unable to support this key
cleanup()
return NewErrKeyExists(k, newKey)
}
target = existing
} else {
// Does not exist, create
target = make(map[string]interface{})
dst[newKey] = target
// If this is the first created key, capture it for
// cleanup if there is an error later.
if createdParent == nil {
createdParent = dst
createdKey = newKey
}
}
// Descend into new m
dst = target
}
// See if the final segment is a valid key
newKey := segments[len(segments)-1]
if newKey == "" {
// String ends in a dot
cleanup()
return ErrInvalidObjectPath
}
dst[newKey] = v
return nil
}
// ctyify converts nested map[string]interfaces to a map[string]cty.Value. An
// error is returned if an unsupported type is encountered.
//
// Currently only strings, cty.Values, and nested maps are supported.
func ctyify(src map[string]interface{}) (map[string]cty.Value, error) {
dst := make(map[string]cty.Value, len(src))
for k, vI := range src {
switch v := vI.(type) {
case string:
dst[k] = cty.StringVal(v)
case cty.Value:
dst[k] = v
case map[string]interface{}:
o, err := ctyify(v)
if err != nil {
return nil, err
}
dst[k] = cty.ObjectVal(o)
default:
return nil, fmt.Errorf("key %q has invalid type %T", k, v)
}
}
return dst, nil
}