terraform/plans/objchange/plan_valid.go

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package objchange
import (
"fmt"
"github.com/zclconf/go-cty/cty"
"github.com/hashicorp/terraform/configs/configschema"
)
// AssertPlanValid checks checks whether a planned new state returned by a
// provider's PlanResourceChange method is suitable to achieve a change
// from priorState to config. It returns a slice with nonzero length if
// any problems are detected. Because problems here indicate bugs in the
// provider that generated the plannedState, they are written with provider
// developers as an audience, rather than end-users.
//
// All of the given values must have the same type and must conform to the
// implied type of the given schema, or this function may panic or produce
// garbage results.
//
// During planning, a provider may only make changes to attributes that are
// null (unset) in the configuration and are marked as "computed" in the
// resource type schema, in order to insert any default values the provider
// may know about. If the default value cannot be determined until apply time,
// the provider can return an unknown value. Providers are forbidden from
// planning a change that disagrees with any non-null argument in the
// configuration.
//
// As a special exception, providers _are_ allowed to provide attribute values
// conflicting with configuration if and only if the planned value exactly
// matches the corresponding attribute value in the prior state. The provider
// can use this to signal that the new value is functionally equivalent to
// the old and thus no change is required.
func AssertPlanValid(schema *configschema.Block, priorState, config, plannedState cty.Value) []error {
return assertPlanValid(schema, priorState, config, plannedState, nil)
}
func assertPlanValid(schema *configschema.Block, priorState, config, plannedState cty.Value, path cty.Path) []error {
var errs []error
if plannedState.IsNull() && !config.IsNull() {
errs = append(errs, path.NewErrorf("planned for absense but config wants existence"))
return errs
}
if config.IsNull() && !plannedState.IsNull() {
errs = append(errs, path.NewErrorf("planned for existence but config wants absense"))
return errs
}
if plannedState.IsNull() {
// No further checks possible if the planned value is null
return errs
}
impTy := schema.ImpliedType()
for name, attrS := range schema.Attributes {
plannedV := plannedState.GetAttr(name)
configV := config.GetAttr(name)
priorV := cty.NullVal(attrS.Type)
if !priorState.IsNull() {
priorV = priorState.GetAttr(name)
}
path := append(path, cty.GetAttrStep{Name: name})
moreErrs := assertPlannedValueValid(attrS, priorV, configV, plannedV, path)
errs = append(errs, moreErrs...)
}
for name, blockS := range schema.BlockTypes {
path := append(path, cty.GetAttrStep{Name: name})
plannedV := plannedState.GetAttr(name)
configV := config.GetAttr(name)
priorV := cty.NullVal(impTy.AttributeType(name))
if !priorState.IsNull() {
priorV = priorState.GetAttr(name)
}
if plannedV.RawEquals(configV) {
// Easy path: nothing has changed at all
continue
}
if !plannedV.IsKnown() {
errs = append(errs, path.NewErrorf("attribute representing nested block must not be unknown itself; set nested attribute values to unknown instead"))
continue
}
switch blockS.Nesting {
case configschema.NestingSingle:
moreErrs := assertPlanValid(&blockS.Block, priorV, configV, plannedV, path)
errs = append(errs, moreErrs...)
case configschema.NestingList:
// A NestingList might either be a list or a tuple, depending on
// whether there are dynamically-typed attributes inside. However,
// both support a similar-enough API that we can treat them the
// same for our purposes here.
if plannedV.IsNull() {
errs = append(errs, path.NewErrorf("attribute representing a list of nested blocks must be empty to indicate no blocks, not null"))
continue
}
plannedL := plannedV.LengthInt()
configL := configV.LengthInt()
if plannedL != configL {
errs = append(errs, path.NewErrorf("block count in plan (%d) disagrees with count in config (%d)", plannedL, configL))
continue
}
for it := plannedV.ElementIterator(); it.Next(); {
idx, plannedEV := it.Element()
path := append(path, cty.IndexStep{Key: idx})
if !plannedEV.IsKnown() {
errs = append(errs, path.NewErrorf("element representing nested block must not be unknown itself; set nested attribute values to unknown instead"))
continue
}
if !configV.HasIndex(idx).True() {
continue // should never happen since we checked the lengths above
}
configEV := configV.Index(idx)
priorEV := cty.NullVal(blockS.ImpliedType())
if !priorV.IsNull() && priorV.HasIndex(idx).True() {
priorEV = priorV.Index(idx)
}
moreErrs := assertPlanValid(&blockS.Block, priorEV, configEV, plannedEV, path)
errs = append(errs, moreErrs...)
}
case configschema.NestingMap:
if plannedV.IsNull() {
errs = append(errs, path.NewErrorf("attribute representing a map of nested blocks must be empty to indicate no blocks, not null"))
continue
}
// A NestingMap might either be a map or an object, depending on
// whether there are dynamically-typed attributes inside, but
// that's decided statically and so all values will have the same
// kind.
if plannedV.Type().IsObjectType() {
plannedAtys := plannedV.Type().AttributeTypes()
configAtys := configV.Type().AttributeTypes()
for k := range plannedAtys {
if _, ok := configAtys[k]; !ok {
errs = append(errs, path.NewErrorf("block key %q from plan is not present in config", k))
continue
}
path := append(path, cty.GetAttrStep{Name: k})
plannedEV := plannedV.GetAttr(k)
if !plannedEV.IsKnown() {
errs = append(errs, path.NewErrorf("element representing nested block must not be unknown itself; set nested attribute values to unknown instead"))
continue
}
configEV := configV.GetAttr(k)
priorEV := cty.NullVal(blockS.ImpliedType())
if !priorV.IsNull() && priorV.Type().HasAttribute(k) {
priorEV = priorV.GetAttr(k)
}
moreErrs := assertPlanValid(&blockS.Block, priorEV, configEV, plannedEV, path)
errs = append(errs, moreErrs...)
}
for k := range configAtys {
if _, ok := plannedAtys[k]; !ok {
errs = append(errs, path.NewErrorf("block key %q from config is not present in plan", k))
continue
}
}
} else {
plannedL := plannedV.LengthInt()
configL := configV.LengthInt()
if plannedL != configL {
errs = append(errs, path.NewErrorf("block count in plan (%d) disagrees with count in config (%d)", plannedL, configL))
continue
}
for it := plannedV.ElementIterator(); it.Next(); {
idx, plannedEV := it.Element()
path := append(path, cty.IndexStep{Key: idx})
if !plannedEV.IsKnown() {
errs = append(errs, path.NewErrorf("element representing nested block must not be unknown itself; set nested attribute values to unknown instead"))
continue
}
k := idx.AsString()
if !configV.HasIndex(idx).True() {
errs = append(errs, path.NewErrorf("block key %q from plan is not present in config", k))
continue
}
configEV := configV.Index(idx)
priorEV := cty.NullVal(blockS.ImpliedType())
if !priorV.IsNull() && priorV.HasIndex(idx).True() {
priorEV = priorV.Index(idx)
}
moreErrs := assertPlanValid(&blockS.Block, priorEV, configEV, plannedEV, path)
errs = append(errs, moreErrs...)
}
for it := configV.ElementIterator(); it.Next(); {
idx, _ := it.Element()
if !plannedV.HasIndex(idx).True() {
errs = append(errs, path.NewErrorf("block key %q from config is not present in plan", idx.AsString()))
continue
}
}
}
case configschema.NestingSet:
if plannedV.IsNull() {
errs = append(errs, path.NewErrorf("attribute representing a set of nested blocks must be empty to indicate no blocks, not null"))
continue
}
// Because set elements have no identifier with which to correlate
// them, we can't robustly validate the plan for a nested block
// backed by a set, and so unfortunately we need to just trust the
// provider to do the right thing. :(
//
// (In principle we could correlate elements by matching the
// subset of attributes explicitly set in config, except for the
// special diff suppression rule which allows for there to be a
// planned value that is constructed by mixing part of a prior
// value with part of a config value, creating an entirely new
// element that is not present in either prior nor config.)
for it := plannedV.ElementIterator(); it.Next(); {
idx, plannedEV := it.Element()
path := append(path, cty.IndexStep{Key: idx})
if !plannedEV.IsKnown() {
errs = append(errs, path.NewErrorf("element representing nested block must not be unknown itself; set nested attribute values to unknown instead"))
continue
}
}
default:
panic(fmt.Sprintf("unsupported nesting mode %s", blockS.Nesting))
}
}
return errs
}
func assertPlannedValueValid(attrS *configschema.Attribute, priorV, configV, plannedV cty.Value, path cty.Path) []error {
var errs []error
if plannedV.RawEquals(configV) {
// This is the easy path: provider didn't change anything at all.
return errs
}
if plannedV.RawEquals(priorV) && !priorV.IsNull() {
// Also pretty easy: there is a prior value and the provider has
// returned it unchanged. This indicates that configV and plannedV
// are functionally equivalent and so the provider wishes to disregard
// the configuration value in favor of the prior.
return errs
}
if attrS.Computed && configV.IsNull() {
// The provider is allowed to change the value of any computed
// attribute that isn't explicitly set in the config.
return errs
}
// If none of the above conditions match, the provider has made an invalid
// change to this attribute.
if priorV.IsNull() {
if attrS.Sensitive {
errs = append(errs, path.NewErrorf("sensitive planned value does not match config value"))
} else {
errs = append(errs, path.NewErrorf("planned value %#v does not match config value %#v", plannedV, configV))
}
return errs
}
if attrS.Sensitive {
errs = append(errs, path.NewErrorf("sensitive planned value does not match config value nor prior value"))
} else {
errs = append(errs, path.NewErrorf("planned value %#v does not match config value %#v nor prior value %#v", plannedV, configV, priorV))
}
return errs
}