terraform/config/raw_config.go

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package config
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import (
"bytes"
"encoding/gob"
"errors"
"strconv"
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"sync"
"github.com/zclconf/go-cty/cty"
"github.com/zclconf/go-cty/cty/convert"
hcl2 "github.com/hashicorp/hcl/v2"
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"github.com/hashicorp/hil"
"github.com/hashicorp/hil/ast"
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"github.com/mitchellh/copystructure"
"github.com/mitchellh/reflectwalk"
)
// 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
// Only _one_ of Raw and Body may be populated at a time.
//
// In the normal case, Raw is populated and Body is nil.
//
// When the experimental HCL2 parsing mode is enabled, "Body"
// is populated and RawConfig serves only to transport the hcl2.Body
// through the rest of Terraform core so we can ultimately decode it
// once its schema is known.
//
// Once we transition to HCL2 as the primary representation, RawConfig
// should be removed altogether and the hcl2.Body should be passed
// around directly.
Raw map[string]interface{}
Body hcl2.Body
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Interpolations []ast.Node
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Variables map[string]InterpolatedVariable
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lock sync.Mutex
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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 {
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return nil, err
}
return result, nil
}
// NewRawConfigHCL2 creates a new RawConfig that is serving as a capsule
// to transport a hcl2.Body. In this mode, the publicly-readable struct
// fields are not populated since all operations should instead be diverted
// to the HCL2 body.
//
// For a RawConfig object constructed with this function, the only valid use
// is to later retrieve the Body value and call its own methods. Callers
// may choose to set and then later handle the Key field, in a manner
// consistent with how it is handled by the Value method, but the Value
// method itself must not be used.
//
// This is an experimental codepath to be used only by the HCL2 config loader.
// Non-experimental parsing should _always_ use NewRawConfig to produce a
// fully-functional RawConfig object.
func NewRawConfigHCL2(body hcl2.Body) *RawConfig {
return &RawConfig{
Body: body,
}
}
// 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
}
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// Copy returns a copy of this RawConfig, uninterpolated.
func (r *RawConfig) Copy() *RawConfig {
if r == nil {
return nil
}
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r.lock.Lock()
defer r.lock.Unlock()
if r.Body != nil {
return NewRawConfigHCL2(r.Body)
}
newRaw := make(map[string]interface{})
for k, v := range r.Raw {
newRaw[k] = v
}
result, err := NewRawConfig(newRaw)
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if err != nil {
panic("copy failed: " + err.Error())
}
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result.Key = r.Key
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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
}
}
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r.lock.Lock()
defer r.lock.Unlock()
return r.Raw[r.Key]
}
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// 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()
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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.
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func (r *RawConfig) Interpolate(vs map[string]ast.Variable) error {
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r.lock.Lock()
defer r.lock.Unlock()
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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)
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if err != nil {
return "", err
}
return result.Value, nil
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})
}
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// 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 {
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r.lock.Lock()
defer r.lock.Unlock()
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// 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{}{}
}
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result.unknownKeys = make([]string, 0, len(unknownKeys))
for k, _ := range unknownKeys {
result.unknownKeys = append(result.unknownKeys, k)
}
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}
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) {
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r.Interpolations = append(r.Interpolations, node)
vars, err := DetectVariables(node)
if err != nil {
return "", err
}
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for _, v := range vars {
if r.Variables == nil {
r.Variables = make(map[string]InterpolatedVariable)
}
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r.Variables[v.FullKey()] = v
}
return "", nil
}
walker := &interpolationWalker{F: fn}
if err := reflectwalk.Walk(r.Raw, walker); err != nil {
return err
}
return nil
}
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func (r *RawConfig) interpolate(fn interpolationWalkerFunc) error {
if r.Body != nil {
// For RawConfigs created for the HCL2 experiement, callers must
// use the HCL2 Body API directly rather than interpolating via
// the RawConfig.
return errors.New("this feature is not yet supported under the HCL2 experiment")
}
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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
}
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func (r *RawConfig) merge(r2 *RawConfig) *RawConfig {
if r == nil && r2 == nil {
return nil
}
if r == nil {
r = &RawConfig{}
}
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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
}
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}
result, err := NewRawConfig(raw)
if err != nil {
panic(err)
}
return result
}
// couldBeInteger is a helper that determines if the represented value could
// result in an integer.
//
// This function only works for RawConfigs that have "Key" set, meaning that
// a single result can be produced. Calling this function will overwrite
// the Config and Value results to be a test value.
//
// This function is conservative. If there is some doubt about whether the
// result could be an integer -- for example, if it depends on a variable
// whose type we don't know yet -- it will still return true.
func (r *RawConfig) couldBeInteger() bool {
if r.Key == "" {
// un-keyed RawConfigs can never produce numbers
return false
}
if r.Body == nil {
// Normal path: using the interpolator in this package
// Interpolate with a fixed number to verify that its a number.
r.interpolate(func(root ast.Node) (interface{}, error) {
// Execute the node but transform the AST so that it returns
// a fixed value of "5" for all interpolations.
result, err := hil.Eval(
hil.FixedValueTransform(
root, &ast.LiteralNode{Value: "5", Typex: ast.TypeString}),
nil)
if err != nil {
return "", err
}
return result.Value, nil
})
_, err := strconv.ParseInt(r.Value().(string), 0, 0)
return err == nil
} else {
// HCL2 experiment path: using the HCL2 API via shims
//
// This path catches fewer situations because we have to assume all
// variables are entirely unknown in HCL2, rather than the assumption
// above that all variables can be numbers because names like "var.foo"
// are considered a single variable rather than an attribute access.
// This is fine in practice, because we get a definitive answer
// during the graph walk when we have real values to work with.
attrs, diags := r.Body.JustAttributes()
if diags.HasErrors() {
// This body is not just a single attribute with a value, so
// this can't be a number.
return false
}
attr, hasAttr := attrs[r.Key]
if !hasAttr {
return false
}
result, diags := hcl2EvalWithUnknownVars(attr.Expr)
if diags.HasErrors() {
// We'll conservatively assume that this error is a result of
// us not being ready to fully-populate the scope, and catch
// any further problems during the main graph walk.
return true
}
// If the result is convertable to number then we'll allow it.
// We do this because an unknown string is optimistically convertable
// to number (might be "5") but a _known_ string "hello" is not.
_, err := convert.Convert(result, cty.Number)
return err == nil
}
}
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// 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()
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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) {
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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{}
}
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// langEvalConfig returns the evaluation configuration we use to execute.
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func langEvalConfig(vs map[string]ast.Variable) *hil.EvalConfig {
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funcMap := make(map[string]ast.Function)
for k, v := range Funcs() {
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funcMap[k] = v
}
funcMap["lookup"] = interpolationFuncLookup(vs)
funcMap["keys"] = interpolationFuncKeys(vs)
funcMap["values"] = interpolationFuncValues(vs)
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return &hil.EvalConfig{
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GlobalScope: &ast.BasicScope{
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VarMap: vs,
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FuncMap: funcMap,
},
}
}