terraform/lang/eval.go

453 lines
16 KiB
Go

package lang
import (
"fmt"
"github.com/hashicorp/hcl/v2"
"github.com/hashicorp/hcl/v2/ext/dynblock"
"github.com/hashicorp/hcl/v2/hcldec"
"github.com/hashicorp/terraform/addrs"
"github.com/hashicorp/terraform/configs/configschema"
"github.com/hashicorp/terraform/internal/instances"
"github.com/hashicorp/terraform/internal/tfdiags"
"github.com/hashicorp/terraform/lang/blocktoattr"
"github.com/zclconf/go-cty/cty"
"github.com/zclconf/go-cty/cty/convert"
)
// ExpandBlock expands any "dynamic" blocks present in the given body. The
// result is a body with those blocks expanded, ready to be evaluated with
// EvalBlock.
//
// If the returned diagnostics contains errors then the result may be
// incomplete or invalid.
func (s *Scope) ExpandBlock(body hcl.Body, schema *configschema.Block) (hcl.Body, tfdiags.Diagnostics) {
spec := schema.DecoderSpec()
traversals := dynblock.ExpandVariablesHCLDec(body, spec)
refs, diags := References(traversals)
ctx, ctxDiags := s.EvalContext(refs)
diags = diags.Append(ctxDiags)
return dynblock.Expand(body, ctx), diags
}
// EvalBlock evaluates the given body using the given block schema and returns
// a cty object value representing its contents. The type of the result conforms
// to the implied type of the given schema.
//
// This function does not automatically expand "dynamic" blocks within the
// body. If that is desired, first call the ExpandBlock method to obtain
// an expanded body to pass to this method.
//
// If the returned diagnostics contains errors then the result may be
// incomplete or invalid.
func (s *Scope) EvalBlock(body hcl.Body, schema *configschema.Block) (cty.Value, tfdiags.Diagnostics) {
spec := schema.DecoderSpec()
refs, diags := ReferencesInBlock(body, schema)
ctx, ctxDiags := s.EvalContext(refs)
diags = diags.Append(ctxDiags)
if diags.HasErrors() {
// We'll stop early if we found problems in the references, because
// it's likely evaluation will produce redundant copies of the same errors.
return cty.UnknownVal(schema.ImpliedType()), diags
}
// HACK: In order to remain compatible with some assumptions made in
// Terraform v0.11 and earlier about the approximate equivalence of
// attribute vs. block syntax, we do a just-in-time fixup here to allow
// any attribute in the schema that has a list-of-objects or set-of-objects
// kind to potentially be populated instead by one or more nested blocks
// whose type is the attribute name.
body = blocktoattr.FixUpBlockAttrs(body, schema)
val, evalDiags := hcldec.Decode(body, spec, ctx)
diags = diags.Append(evalDiags)
return val, diags
}
// EvalSelfBlock evaluates the given body only within the scope of the provided
// object and instance key data. References to the object must use self, and the
// key data will only contain count.index or each.key. The static values for
// terraform and path will also be available in this context.
func (s *Scope) EvalSelfBlock(body hcl.Body, self cty.Value, schema *configschema.Block, keyData instances.RepetitionData) (cty.Value, tfdiags.Diagnostics) {
var diags tfdiags.Diagnostics
spec := schema.DecoderSpec()
vals := make(map[string]cty.Value)
vals["self"] = self
if !keyData.CountIndex.IsNull() {
vals["count"] = cty.ObjectVal(map[string]cty.Value{
"index": keyData.CountIndex,
})
}
if !keyData.EachKey.IsNull() {
vals["each"] = cty.ObjectVal(map[string]cty.Value{
"key": keyData.EachKey,
})
}
refs, refDiags := References(hcldec.Variables(body, spec))
diags = diags.Append(refDiags)
terraformAttrs := map[string]cty.Value{}
pathAttrs := map[string]cty.Value{}
// We could always load the static values for Path and Terraform values,
// but we want to parse the references so that we can get source ranges for
// user diagnostics.
for _, ref := range refs {
// we already loaded the self value
if ref.Subject == addrs.Self {
continue
}
switch subj := ref.Subject.(type) {
case addrs.PathAttr:
val, valDiags := normalizeRefValue(s.Data.GetPathAttr(subj, ref.SourceRange))
diags = diags.Append(valDiags)
pathAttrs[subj.Name] = val
case addrs.TerraformAttr:
val, valDiags := normalizeRefValue(s.Data.GetTerraformAttr(subj, ref.SourceRange))
diags = diags.Append(valDiags)
terraformAttrs[subj.Name] = val
case addrs.CountAttr, addrs.ForEachAttr:
// each and count have already been handled.
default:
// This should have been caught in validation, but point the user
// to the correct location in case something slipped through.
diags = diags.Append(&hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: `Invalid reference`,
Detail: fmt.Sprintf("The reference to %q is not valid in this context", ref.Subject),
Subject: ref.SourceRange.ToHCL().Ptr(),
})
}
}
vals["path"] = cty.ObjectVal(pathAttrs)
vals["terraform"] = cty.ObjectVal(terraformAttrs)
ctx := &hcl.EvalContext{
Variables: vals,
Functions: s.Functions(),
}
val, decDiags := hcldec.Decode(body, schema.DecoderSpec(), ctx)
diags = diags.Append(decDiags)
return val, diags
}
// EvalExpr evaluates a single expression in the receiving context and returns
// the resulting value. The value will be converted to the given type before
// it is returned if possible, or else an error diagnostic will be produced
// describing the conversion error.
//
// Pass an expected type of cty.DynamicPseudoType to skip automatic conversion
// and just obtain the returned value directly.
//
// If the returned diagnostics contains errors then the result may be
// incomplete, but will always be of the requested type.
func (s *Scope) EvalExpr(expr hcl.Expression, wantType cty.Type) (cty.Value, tfdiags.Diagnostics) {
refs, diags := ReferencesInExpr(expr)
ctx, ctxDiags := s.EvalContext(refs)
diags = diags.Append(ctxDiags)
if diags.HasErrors() {
// We'll stop early if we found problems in the references, because
// it's likely evaluation will produce redundant copies of the same errors.
return cty.UnknownVal(wantType), diags
}
val, evalDiags := expr.Value(ctx)
diags = diags.Append(evalDiags)
if wantType != cty.DynamicPseudoType {
var convErr error
val, convErr = convert.Convert(val, wantType)
if convErr != nil {
val = cty.UnknownVal(wantType)
diags = diags.Append(&hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Incorrect value type",
Detail: fmt.Sprintf("Invalid expression value: %s.", tfdiags.FormatError(convErr)),
Subject: expr.Range().Ptr(),
Expression: expr,
EvalContext: ctx,
})
}
}
return val, diags
}
// EvalReference evaluates the given reference in the receiving scope and
// returns the resulting value. The value will be converted to the given type before
// it is returned if possible, or else an error diagnostic will be produced
// describing the conversion error.
//
// Pass an expected type of cty.DynamicPseudoType to skip automatic conversion
// and just obtain the returned value directly.
//
// If the returned diagnostics contains errors then the result may be
// incomplete, but will always be of the requested type.
func (s *Scope) EvalReference(ref *addrs.Reference, wantType cty.Type) (cty.Value, tfdiags.Diagnostics) {
var diags tfdiags.Diagnostics
// We cheat a bit here and just build an EvalContext for our requested
// reference with the "self" address overridden, and then pull the "self"
// result out of it to return.
ctx, ctxDiags := s.evalContext([]*addrs.Reference{ref}, ref.Subject)
diags = diags.Append(ctxDiags)
val := ctx.Variables["self"]
if val == cty.NilVal {
val = cty.DynamicVal
}
var convErr error
val, convErr = convert.Convert(val, wantType)
if convErr != nil {
val = cty.UnknownVal(wantType)
diags = diags.Append(&hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Incorrect value type",
Detail: fmt.Sprintf("Invalid expression value: %s.", tfdiags.FormatError(convErr)),
Subject: ref.SourceRange.ToHCL().Ptr(),
})
}
return val, diags
}
// EvalContext constructs a HCL expression evaluation context whose variable
// scope contains sufficient values to satisfy the given set of references.
//
// Most callers should prefer to use the evaluation helper methods that
// this type offers, but this is here for less common situations where the
// caller will handle the evaluation calls itself.
func (s *Scope) EvalContext(refs []*addrs.Reference) (*hcl.EvalContext, tfdiags.Diagnostics) {
return s.evalContext(refs, s.SelfAddr)
}
func (s *Scope) evalContext(refs []*addrs.Reference, selfAddr addrs.Referenceable) (*hcl.EvalContext, tfdiags.Diagnostics) {
if s == nil {
panic("attempt to construct EvalContext for nil Scope")
}
var diags tfdiags.Diagnostics
vals := make(map[string]cty.Value)
funcs := s.Functions()
ctx := &hcl.EvalContext{
Variables: vals,
Functions: funcs,
}
if len(refs) == 0 {
// Easy path for common case where there are no references at all.
return ctx, diags
}
// First we'll do static validation of the references. This catches things
// early that might otherwise not get caught due to unknown values being
// present in the scope during planning.
if staticDiags := s.Data.StaticValidateReferences(refs, selfAddr); staticDiags.HasErrors() {
diags = diags.Append(staticDiags)
return ctx, diags
}
// The reference set we are given has not been de-duped, and so there can
// be redundant requests in it for two reasons:
// - The same item is referenced multiple times
// - Both an item and that item's container are separately referenced.
// We will still visit every reference here and ask our data source for
// it, since that allows us to gather a full set of any errors and
// warnings, but once we've gathered all the data we'll then skip anything
// that's redundant in the process of populating our values map.
dataResources := map[string]map[string]cty.Value{}
managedResources := map[string]map[string]cty.Value{}
wholeModules := map[string]cty.Value{}
inputVariables := map[string]cty.Value{}
localValues := map[string]cty.Value{}
pathAttrs := map[string]cty.Value{}
terraformAttrs := map[string]cty.Value{}
countAttrs := map[string]cty.Value{}
forEachAttrs := map[string]cty.Value{}
var self cty.Value
for _, ref := range refs {
rng := ref.SourceRange
rawSubj := ref.Subject
if rawSubj == addrs.Self {
if selfAddr == nil {
diags = diags.Append(&hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: `Invalid "self" reference`,
// This detail message mentions some current practice that
// this codepath doesn't really "know about". If the "self"
// object starts being supported in more contexts later then
// we'll need to adjust this message.
Detail: `The "self" object is not available in this context. This object can be used only in resource provisioner and connection blocks.`,
Subject: ref.SourceRange.ToHCL().Ptr(),
})
continue
}
if selfAddr == addrs.Self {
// Programming error: the self address cannot alias itself.
panic("scope SelfAddr attempting to alias itself")
}
// self can only be used within a resource instance
subj := selfAddr.(addrs.ResourceInstance)
val, valDiags := normalizeRefValue(s.Data.GetResource(subj.ContainingResource(), rng))
diags = diags.Append(valDiags)
// Self is an exception in that it must always resolve to a
// particular instance. We will still insert the full resource into
// the context below.
var hclDiags hcl.Diagnostics
// We should always have a valid self index by this point, but in
// the case of an error, self may end up as a cty.DynamicValue.
switch k := subj.Key.(type) {
case addrs.IntKey:
self, hclDiags = hcl.Index(val, cty.NumberIntVal(int64(k)), ref.SourceRange.ToHCL().Ptr())
diags = diags.Append(hclDiags)
case addrs.StringKey:
self, hclDiags = hcl.Index(val, cty.StringVal(string(k)), ref.SourceRange.ToHCL().Ptr())
diags = diags.Append(hclDiags)
default:
self = val
}
continue
}
// This type switch must cover all of the "Referenceable" implementations
// in package addrs, however we are removing the possibility of
// Instances beforehand.
switch addr := rawSubj.(type) {
case addrs.ResourceInstance:
rawSubj = addr.ContainingResource()
case addrs.ModuleCallInstance:
rawSubj = addr.Call
case addrs.AbsModuleCallOutput:
rawSubj = addr.Call.Call
}
switch subj := rawSubj.(type) {
case addrs.Resource:
var into map[string]map[string]cty.Value
switch subj.Mode {
case addrs.ManagedResourceMode:
into = managedResources
case addrs.DataResourceMode:
into = dataResources
default:
panic(fmt.Errorf("unsupported ResourceMode %s", subj.Mode))
}
val, valDiags := normalizeRefValue(s.Data.GetResource(subj, rng))
diags = diags.Append(valDiags)
r := subj
if into[r.Type] == nil {
into[r.Type] = make(map[string]cty.Value)
}
into[r.Type][r.Name] = val
case addrs.ModuleCall:
val, valDiags := normalizeRefValue(s.Data.GetModule(subj, rng))
diags = diags.Append(valDiags)
wholeModules[subj.Name] = val
case addrs.InputVariable:
val, valDiags := normalizeRefValue(s.Data.GetInputVariable(subj, rng))
diags = diags.Append(valDiags)
inputVariables[subj.Name] = val
case addrs.LocalValue:
val, valDiags := normalizeRefValue(s.Data.GetLocalValue(subj, rng))
diags = diags.Append(valDiags)
localValues[subj.Name] = val
case addrs.PathAttr:
val, valDiags := normalizeRefValue(s.Data.GetPathAttr(subj, rng))
diags = diags.Append(valDiags)
pathAttrs[subj.Name] = val
case addrs.TerraformAttr:
val, valDiags := normalizeRefValue(s.Data.GetTerraformAttr(subj, rng))
diags = diags.Append(valDiags)
terraformAttrs[subj.Name] = val
case addrs.CountAttr:
val, valDiags := normalizeRefValue(s.Data.GetCountAttr(subj, rng))
diags = diags.Append(valDiags)
countAttrs[subj.Name] = val
case addrs.ForEachAttr:
val, valDiags := normalizeRefValue(s.Data.GetForEachAttr(subj, rng))
diags = diags.Append(valDiags)
forEachAttrs[subj.Name] = val
default:
// Should never happen
panic(fmt.Errorf("Scope.buildEvalContext cannot handle address type %T", rawSubj))
}
}
// Managed resources are exposed in two different locations. The primary
// is at the top level where the resource type name is the root of the
// traversal, but we also expose them under "resource" as an escaping
// technique if we add a reserved name in a future language edition which
// conflicts with someone's existing provider.
for k, v := range buildResourceObjects(managedResources) {
vals[k] = v
}
vals["resource"] = cty.ObjectVal(buildResourceObjects(managedResources))
vals["data"] = cty.ObjectVal(buildResourceObjects(dataResources))
vals["module"] = cty.ObjectVal(wholeModules)
vals["var"] = cty.ObjectVal(inputVariables)
vals["local"] = cty.ObjectVal(localValues)
vals["path"] = cty.ObjectVal(pathAttrs)
vals["terraform"] = cty.ObjectVal(terraformAttrs)
vals["count"] = cty.ObjectVal(countAttrs)
vals["each"] = cty.ObjectVal(forEachAttrs)
if self != cty.NilVal {
vals["self"] = self
}
return ctx, diags
}
func buildResourceObjects(resources map[string]map[string]cty.Value) map[string]cty.Value {
vals := make(map[string]cty.Value)
for typeName, nameVals := range resources {
vals[typeName] = cty.ObjectVal(nameVals)
}
return vals
}
func normalizeRefValue(val cty.Value, diags tfdiags.Diagnostics) (cty.Value, tfdiags.Diagnostics) {
if diags.HasErrors() {
// If there are errors then we will force an unknown result so that
// we can still evaluate and catch type errors but we'll avoid
// producing redundant re-statements of the same errors we've already
// dealt with here.
return cty.UnknownVal(val.Type()), diags
}
return val, diags
}