package config
import (
"bytes"
"encoding/gob"
"sync"
"github.com/hashicorp/hil"
"github.com/hashicorp/hil/ast"
"github.com/mitchellh/copystructure"
"github.com/mitchellh/reflectwalk"
)
// UnknownVariableValue is a sentinel value that can be used
// to denote that the value of a variable is unknown at this time.
// RawConfig uses this information to build up data about
// unknown keys.
const UnknownVariableValue = "74D93920-ED26-11E3-AC10-0800200C9A66"
// RawConfig is a structure that holds a piece of configuration
// where the overall structure is unknown since it will be used
// to configure a plugin or some other similar external component.
//
// RawConfigs can be interpolated with variables that come from
// other resources, user variables, etc.
//
// RawConfig supports a query-like interface to request
// information from deep within the structure.
type RawConfig struct {
Key string
Raw map[string]interface{}
Interpolations []ast.Node
Variables map[string]InterpolatedVariable
lock sync.Mutex
config map[string]interface{}
unknownKeys []string
}
// NewRawConfig creates a new RawConfig structure and populates the
// publicly readable struct fields.
func NewRawConfig(raw map[string]interface{}) (*RawConfig, error) {
result := &RawConfig{Raw: raw}
if err := result.init(); err != nil {
return nil, err
}
return result, nil
}
// RawMap returns a copy of the RawConfig.Raw map.
func (r *RawConfig) RawMap() map[string]interface{} {
r.lock.Lock()
defer r.lock.Unlock()
m := make(map[string]interface{})
for k, v := range r.Raw {
m[k] = v
}
return m
}
// Copy returns a copy of this RawConfig, uninterpolated.
func (r *RawConfig) Copy() *RawConfig {
if r == nil {
return nil
}
r.lock.Lock()
defer r.lock.Unlock()
newRaw := make(map[string]interface{})
for k, v := range r.Raw {
newRaw[k] = v
}
result, err := NewRawConfig(newRaw)
if err != nil {
panic("copy failed: " + err.Error())
}
result.Key = r.Key
return result
}
// Value returns the value of the configuration if this configuration
// has a Key set. If this does not have a Key set, nil will be returned.
func (r *RawConfig) Value() interface{} {
if c := r.Config(); c != nil {
if v, ok := c[r.Key]; ok {
return v
}
}
r.lock.Lock()
defer r.lock.Unlock()
return r.Raw[r.Key]
}
// Config returns the entire configuration with the variables
// interpolated from any call to Interpolate.
//
// If any interpolated variables are unknown (value set to
// UnknownVariableValue), the first non-container (map, slice, etc.) element
// will be removed from the config. The keys of unknown variables
// can be found using the UnknownKeys function.
//
// By pruning out unknown keys from the configuration, the raw
// structure will always successfully decode into its ultimate
// structure using something like mapstructure.
func (r *RawConfig) Config() map[string]interface{} {
r.lock.Lock()
defer r.lock.Unlock()
return r.config
}
// Interpolate uses the given mapping of variable values and uses
// those as the values to replace any variables in this raw
// configuration.
//
// Any prior calls to Interpolate are replaced with this one.
//
// If a variable key is missing, this will panic.
func (r *RawConfig) Interpolate(vs map[string]ast.Variable) error {
r.lock.Lock()
defer r.lock.Unlock()
config := langEvalConfig(vs)
return r.interpolate(func(root ast.Node) (interface{}, error) {
// None of the variables we need are computed, meaning we should
// be able to properly evaluate.
result, err := hil.Eval(root, config)
if err != nil {
return "", err
}
return result.Value, nil
})
}
// Merge merges another RawConfig into this one (overriding any conflicting
// values in this config) and returns a new config. The original config
// is not modified.
func (r *RawConfig) Merge(other *RawConfig) *RawConfig {
r.lock.Lock()
defer r.lock.Unlock()
// Merge the raw configurations
raw := make(map[string]interface{})
for k, v := range r.Raw {
raw[k] = v
}
for k, v := range other.Raw {
raw[k] = v
}
// Create the result
result, err := NewRawConfig(raw)
if err != nil {
panic(err)
}
// Merge the interpolated results
result.config = make(map[string]interface{})
for k, v := range r.config {
result.config[k] = v
}
for k, v := range other.config {
result.config[k] = v
}
// Build the unknown keys
if len(r.unknownKeys) > 0 || len(other.unknownKeys) > 0 {
unknownKeys := make(map[string]struct{})
for _, k := range r.unknownKeys {
unknownKeys[k] = struct{}{}
}
for _, k := range other.unknownKeys {
unknownKeys[k] = struct{}{}
}
result.unknownKeys = make([]string, 0, len(unknownKeys))
for k, _ := range unknownKeys {
result.unknownKeys = append(result.unknownKeys, k)
}
}
return result
}
func (r *RawConfig) init() error {
r.lock.Lock()
defer r.lock.Unlock()
r.config = r.Raw
r.Interpolations = nil
r.Variables = nil
fn := func(node ast.Node) (interface{}, error) {
r.Interpolations = append(r.Interpolations, node)
vars, err := DetectVariables(node)
if err != nil {
return "", err
}
for _, v := range vars {
if r.Variables == nil {
r.Variables = make(map[string]InterpolatedVariable)
}
r.Variables[v.FullKey()] = v
}
return "", nil
}
walker := &interpolationWalker{F: fn}
if err := reflectwalk.Walk(r.Raw, walker); err != nil {
return err
}
return nil
}
func (r *RawConfig) interpolate(fn interpolationWalkerFunc) error {
config, err := copystructure.Copy(r.Raw)
if err != nil {
return err
}
r.config = config.(map[string]interface{})
w := &interpolationWalker{F: fn, Replace: true}
err = reflectwalk.Walk(r.config, w)
if err != nil {
return err
}
r.unknownKeys = w.unknownKeys
return nil
}
func (r *RawConfig) merge(r2 *RawConfig) *RawConfig {
if r == nil && r2 == nil {
return nil
}
if r == nil {
r = &RawConfig{}
}
rawRaw, err := copystructure.Copy(r.Raw)
if err != nil {
panic(err)
}
raw := rawRaw.(map[string]interface{})
if r2 != nil {
for k, v := range r2.Raw {
raw[k] = v
}
}
result, err := NewRawConfig(raw)
if err != nil {
panic(err)
}
return result
}
// UnknownKeys returns the keys of the configuration that are unknown
// because they had interpolated variables that must be computed.
func (r *RawConfig) UnknownKeys() []string {
r.lock.Lock()
defer r.lock.Unlock()
return r.unknownKeys
}
// See GobEncode
func (r *RawConfig) GobDecode(b []byte) error {
var data gobRawConfig
err := gob.NewDecoder(bytes.NewReader(b)).Decode(&data)
if err != nil {
return err
}
r.Key = data.Key
r.Raw = data.Raw
return r.init()
}
// GobEncode is a custom Gob encoder to use so that we only include the
// raw configuration. Interpolated variables and such are lost and the
// tree of interpolated variables is recomputed on decode, since it is
// referentially transparent.
func (r *RawConfig) GobEncode() ([]byte, error) {
r.lock.Lock()
defer r.lock.Unlock()
data := gobRawConfig{
Key: r.Key,
Raw: r.Raw,
}
var buf bytes.Buffer
if err := gob.NewEncoder(&buf).Encode(data); err != nil {
return nil, err
}
return buf.Bytes(), nil
}
type gobRawConfig struct {
Key string
Raw map[string]interface{}
}
// langEvalConfig returns the evaluation configuration we use to execute.
func langEvalConfig(vs map[string]ast.Variable) *hil.EvalConfig {
funcMap := make(map[string]ast.Function)
for k, v := range Funcs() {
funcMap[k] = v
}
funcMap["lookup"] = interpolationFuncLookup(vs)
funcMap["keys"] = interpolationFuncKeys(vs)
funcMap["values"] = interpolationFuncValues(vs)
return &hil.EvalConfig{
GlobalScope: &ast.BasicScope{
VarMap: vs,
FuncMap: funcMap,
},
}
}
