terraform/plans/changes.go

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package plans
import (
"github.com/hashicorp/terraform/addrs"
"github.com/hashicorp/terraform/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 []*ResourceInstanceChangeSrc
RootOutputs map[string]*OutputChangeSrc
}
// NewChanges returns a valid Changes object that describes no changes.
func NewChanges() *Changes {
return &Changes{
RootOutputs: make(map[string]*OutputChangeSrc),
}
}
func (c *Changes) Empty() bool {
return (len(c.Resources) + len(c.RootOutputs)) == 0
}
// 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 {
addrStr := addr.String()
for _, rc := range c.Resources {
if rc.Addr.String() == addrStr && rc.DeposedKey == states.NotDeposed {
return rc
}
}
return nil
}
// 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 {
addrStr := addr.String()
for _, rc := range c.Resources {
if rc.Addr.String() == addrStr && rc.DeposedKey == key {
return rc
}
}
return nil
}
// 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
// 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,
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 Replace:
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 Replace:
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
}
// OutputChange describes a change to an output value.
type OutputChange struct {
// 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{
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) {
beforeDV, err := NewDynamicValue(c.Before, ty)
if err != nil {
return nil, err
}
afterDV, err := NewDynamicValue(c.After, ty)
if err != nil {
return nil, err
}
return &ChangeSrc{
Action: c.Action,
Before: beforeDV,
After: afterDV,
}, nil
}