terraform/internal/plans/changes.go

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package plans
import (
"github.com/hashicorp/terraform/internal/addrs"
"github.com/hashicorp/terraform/internal/states"
"github.com/zclconf/go-cty/cty"
)
// Changes describes various actions that Terraform will attempt to take if
// the corresponding plan is applied.
//
// A Changes object can be rendered into a visual diff (by the caller, using
// code in another package) for display to the user.
type Changes struct {
// Resources tracks planned changes to resource instance objects.
Resources []*ResourceInstanceChangeSrc
// Outputs tracks planned changes output values.
//
// Note that although an in-memory plan contains planned changes for
// outputs throughout the configuration, a plan serialized
// to disk retains only the root outputs because they are
// externally-visible, while other outputs are implementation details and
// can be easily re-calculated during the apply phase. Therefore only root
// module outputs will survive a round-trip through a plan file.
Outputs []*OutputChangeSrc
}
// NewChanges returns a valid Changes object that describes no changes.
func NewChanges() *Changes {
return &Changes{}
}
func (c *Changes) Empty() bool {
for _, res := range c.Resources {
if res.Action != NoOp {
return false
}
}
for _, out := range c.Outputs {
if out.Addr.Module.IsRoot() && out.Action != NoOp {
return false
}
}
return true
}
// ResourceInstance returns the planned change for the current object of the
// resource instance of the given address, if any. Returns nil if no change is
// planned.
func (c *Changes) ResourceInstance(addr addrs.AbsResourceInstance) *ResourceInstanceChangeSrc {
for _, rc := range c.Resources {
if rc.Addr.Equal(addr) && rc.DeposedKey == states.NotDeposed {
return rc
}
}
return nil
}
// InstancesForConfigResource returns the planned change for the current objects
// of the resource instances of the given address, if any. Returns nil if no
// changes are planned.
func (c *Changes) InstancesForConfigResource(addr addrs.ConfigResource) []*ResourceInstanceChangeSrc {
var changes []*ResourceInstanceChangeSrc
for _, rc := range c.Resources {
resAddr := rc.Addr.ContainingResource().Config()
if resAddr.Equal(addr) && rc.DeposedKey == states.NotDeposed {
changes = append(changes, rc)
}
}
return changes
}
// ResourceInstanceDeposed returns the plan change of a deposed object of
// the resource instance of the given address, if any. Returns nil if no change
// is planned.
func (c *Changes) ResourceInstanceDeposed(addr addrs.AbsResourceInstance, key states.DeposedKey) *ResourceInstanceChangeSrc {
for _, rc := range c.Resources {
if rc.Addr.Equal(addr) && rc.DeposedKey == key {
return rc
}
}
return nil
}
// OutputValue returns the planned change for the output value with the
// given address, if any. Returns nil if no change is planned.
func (c *Changes) OutputValue(addr addrs.AbsOutputValue) *OutputChangeSrc {
for _, oc := range c.Outputs {
if oc.Addr.Equal(addr) {
return oc
}
}
return nil
}
// OutputValues returns planned changes for all outputs for all module
// instances that reside in the parent path. Returns nil if no changes are
// planned.
func (c *Changes) OutputValues(parent addrs.ModuleInstance, module addrs.ModuleCall) []*OutputChangeSrc {
var res []*OutputChangeSrc
for _, oc := range c.Outputs {
2020-04-13 22:21:09 +02:00
// we can't evaluate root module outputs
if oc.Addr.Module.Equal(addrs.RootModuleInstance) {
continue
}
changeMod, changeCall := oc.Addr.Module.Call()
// this does not reside on our parent instance path
if !changeMod.Equal(parent) {
continue
}
// this is not the module you're looking for
if changeCall.Name != module.Name {
continue
}
res = append(res, oc)
}
return res
}
// SyncWrapper returns a wrapper object around the receiver that can be used
// to make certain changes to the receiver in a concurrency-safe way, as long
// as all callers share the same wrapper object.
func (c *Changes) SyncWrapper() *ChangesSync {
return &ChangesSync{
changes: c,
}
}
// ResourceInstanceChange describes a change to a particular resource instance
// object.
type ResourceInstanceChange struct {
// Addr is the absolute address of the resource instance that the change
// will apply to.
Addr addrs.AbsResourceInstance
// DeposedKey is the identifier for a deposed object associated with the
// given instance, or states.NotDeposed if this change applies to the
// current object.
//
// A Replace change for a resource with create_before_destroy set will
// create a new DeposedKey temporarily during replacement. In that case,
// DeposedKey in the plan is always states.NotDeposed, representing that
// the current object is being replaced with the deposed.
DeposedKey states.DeposedKey
// Provider is the address of the provider configuration that was used
// to plan this change, and thus the configuration that must also be
// used to apply it.
ProviderAddr addrs.AbsProviderConfig
// Change is an embedded description of the change.
Change
// ActionReason is an optional extra indication of why we chose the
// action recorded in Change.Action for this particular resource instance.
//
// This is an approximate mechanism only for the purpose of explaining the
// plan to end-users in the UI and is not to be used for any
// decision-making during the apply step; if apply behavior needs to vary
// depending on the "action reason" then the information for that decision
// must be recorded more precisely elsewhere for that purpose.
//
// Sometimes there might be more than one reason for choosing a particular
// action. In that case, it's up to the codepath making that decision to
// decide which value would provide the most relevant explanation to the
// end-user and return that. It's not a goal of this field to represent
// fine details about the planning process.
ActionReason ResourceInstanceChangeActionReason
// RequiredReplace is a set of paths that caused the change action to be
// Replace rather than Update. Always nil if the change action is not
// Replace.
//
// This is retained only for UI-plan-rendering purposes and so it does not
// currently survive a round-trip through a saved plan file.
RequiredReplace cty.PathSet
// Private allows a provider to stash any extra data that is opaque to
// Terraform that relates to this change. Terraform will save this
// byte-for-byte and return it to the provider in the apply call.
Private []byte
}
// Encode produces a variant of the reciever that has its change values
// serialized so it can be written to a plan file. Pass the implied type of the
// corresponding resource type schema for correct operation.
func (rc *ResourceInstanceChange) Encode(ty cty.Type) (*ResourceInstanceChangeSrc, error) {
cs, err := rc.Change.Encode(ty)
if err != nil {
return nil, err
}
return &ResourceInstanceChangeSrc{
Addr: rc.Addr,
DeposedKey: rc.DeposedKey,
ProviderAddr: rc.ProviderAddr,
ChangeSrc: *cs,
ActionReason: rc.ActionReason,
RequiredReplace: rc.RequiredReplace,
Private: rc.Private,
}, err
}
// Simplify will, where possible, produce a change with a simpler action than
// the receiever given a flag indicating whether the caller is dealing with
// a normal apply or a destroy. This flag deals with the fact that Terraform
// Core uses a specialized graph node type for destroying; only that
// specialized node should set "destroying" to true.
//
// The following table shows the simplification behavior:
//
// Action Destroying? New Action
// --------+-------------+-----------
// Create true NoOp
// Delete false NoOp
// Replace true Delete
// Replace false Create
//
// For any combination not in the above table, the Simplify just returns the
// receiver as-is.
func (rc *ResourceInstanceChange) Simplify(destroying bool) *ResourceInstanceChange {
if destroying {
switch rc.Action {
case Delete:
// We'll fall out and just return rc verbatim, then.
case CreateThenDelete, DeleteThenCreate:
return &ResourceInstanceChange{
Addr: rc.Addr,
DeposedKey: rc.DeposedKey,
Private: rc.Private,
ProviderAddr: rc.ProviderAddr,
Change: Change{
Action: Delete,
Before: rc.Before,
After: cty.NullVal(rc.Before.Type()),
},
}
default:
return &ResourceInstanceChange{
Addr: rc.Addr,
DeposedKey: rc.DeposedKey,
Private: rc.Private,
ProviderAddr: rc.ProviderAddr,
Change: Change{
Action: NoOp,
Before: rc.Before,
After: rc.Before,
},
}
}
} else {
switch rc.Action {
case Delete:
return &ResourceInstanceChange{
Addr: rc.Addr,
DeposedKey: rc.DeposedKey,
Private: rc.Private,
ProviderAddr: rc.ProviderAddr,
Change: Change{
Action: NoOp,
Before: rc.Before,
After: rc.Before,
},
}
case CreateThenDelete, DeleteThenCreate:
return &ResourceInstanceChange{
Addr: rc.Addr,
DeposedKey: rc.DeposedKey,
Private: rc.Private,
ProviderAddr: rc.ProviderAddr,
Change: Change{
Action: Create,
Before: cty.NullVal(rc.After.Type()),
After: rc.After,
},
}
}
}
// If we fall out here then our change is already simple enough.
return rc
}
// ResourceInstanceChangeActionReason allows for some extra user-facing
// reasoning for why a particular change action was chosen for a particular
// resource instance.
//
// This only represents sufficient detail to give a suitable explanation to
// an end-user, and mustn't be used for any real decision-making during the
// apply step.
type ResourceInstanceChangeActionReason rune
//go:generate go run golang.org/x/tools/cmd/stringer -type=ResourceInstanceChangeActionReason changes.go
const (
// In most cases there's no special reason for choosing a particular
// action, which is represented by ResourceInstanceChangeNoReason.
ResourceInstanceChangeNoReason ResourceInstanceChangeActionReason = 0
// ResourceInstanceReplaceBecauseTainted indicates that the resource
// instance must be replaced because its existing current object is
// marked as "tainted".
ResourceInstanceReplaceBecauseTainted ResourceInstanceChangeActionReason = 'T'
// ResourceInstanceReplaceByRequest indicates that the resource instance
// is planned to be replaced because a caller specifically asked for it
// to be using ReplaceAddrs. (On the command line, the -replace=...
// planning option.)
ResourceInstanceReplaceByRequest ResourceInstanceChangeActionReason = 'R'
// ResourceInstanceReplaceBecauseCannotUpdate indicates that the resource
// instance is planned to be replaced because the provider has indicated
// that a requested change cannot be applied as an update.
//
// In this case, the RequiredReplace field will typically be populated on
// the ResourceInstanceChange object to give information about specifically
// which arguments changed in a non-updatable way.
ResourceInstanceReplaceBecauseCannotUpdate ResourceInstanceChangeActionReason = 'F'
)
// OutputChange describes a change to an output value.
type OutputChange struct {
// Addr is the absolute address of the output value that the change
// will apply to.
Addr addrs.AbsOutputValue
// Change is an embedded description of the change.
//
// For output value changes, the type constraint for the DynamicValue
// instances is always cty.DynamicPseudoType.
Change
// Sensitive, if true, indicates that either the old or new value in the
// change is sensitive and so a rendered version of the plan in the UI
// should elide the actual values while still indicating the action of the
// change.
Sensitive bool
}
// Encode produces a variant of the reciever that has its change values
// serialized so it can be written to a plan file.
func (oc *OutputChange) Encode() (*OutputChangeSrc, error) {
cs, err := oc.Change.Encode(cty.DynamicPseudoType)
if err != nil {
return nil, err
}
return &OutputChangeSrc{
Addr: oc.Addr,
ChangeSrc: *cs,
Sensitive: oc.Sensitive,
}, err
}
// Change describes a single change with a given action.
type Change struct {
// Action defines what kind of change is being made.
Action Action
// Interpretation of Before and After depend on Action:
//
// NoOp Before and After are the same, unchanged value
// Create Before is nil, and After is the expected value after create.
// Read Before is any prior value (nil if no prior), and After is the
// value that was or will be read.
// Update Before is the value prior to update, and After is the expected
// value after update.
// Replace As with Update.
// Delete Before is the value prior to delete, and After is always nil.
//
// Unknown values may appear anywhere within the Before and After values,
// either as the values themselves or as nested elements within known
// collections/structures.
Before, After cty.Value
}
// Encode produces a variant of the reciever that has its change values
// serialized so it can be written to a plan file. Pass the type constraint
// that the values are expected to conform to; to properly decode the values
// later an identical type constraint must be provided at that time.
//
// Where a Change is embedded in some other struct, it's generally better
// to call the corresponding Encode method of that struct rather than working
// directly with its embedded Change.
func (c *Change) Encode(ty cty.Type) (*ChangeSrc, error) {
// Storing unmarked values so that we can encode unmarked values
// and save the PathValueMarks for re-marking the values later
var beforeVM, afterVM []cty.PathValueMarks
unmarkedBefore := c.Before
unmarkedAfter := c.After
if c.Before.ContainsMarked() {
unmarkedBefore, beforeVM = c.Before.UnmarkDeepWithPaths()
}
beforeDV, err := NewDynamicValue(unmarkedBefore, ty)
if err != nil {
return nil, err
}
if c.After.ContainsMarked() {
unmarkedAfter, afterVM = c.After.UnmarkDeepWithPaths()
}
afterDV, err := NewDynamicValue(unmarkedAfter, ty)
if err != nil {
return nil, err
}
return &ChangeSrc{
Action: c.Action,
Before: beforeDV,
After: afterDV,
BeforeValMarks: beforeVM,
AfterValMarks: afterVM,
}, nil
}