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 te 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) { // We detect the variables again and check if the value of any // of the variables is the computed value. If it is, then we // treat this entire value as computed. // // We have to do this here before the `lang.Eval` because // if any of the variables it depends on are computed, then // the interpolation can fail at runtime for other reasons. Example: // `${count.index+1}`: in a world where `count.index` is computed, // this would fail a type check since the computed placeholder is // a string, but realistically the whole value is just computed. vars, err := DetectVariables(root) if err != nil { return "", err } for _, v := range vars { varVal, ok := vs[v.FullKey()] if ok && varVal.Value == UnknownVariableValue { return UnknownVariableValue, nil } } // 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 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 { rawRaw, err := copystructure.Copy(r.Raw) if err != nil { panic(err) } raw := rawRaw.(map[string]interface{}) 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, }, } }