1package states
2
3import (
4	"github.com/zclconf/go-cty/cty"
5	ctyjson "github.com/zclconf/go-cty/cty/json"
6
7	"github.com/hashicorp/terraform-plugin-sdk/internal/addrs"
8)
9
10// ResourceInstanceObject is the local representation of a specific remote
11// object associated with a resource instance. In practice not all remote
12// objects are actually remote in the sense of being accessed over the network,
13// but this is the most common case.
14//
15// It is not valid to mutate a ResourceInstanceObject once it has been created.
16// Instead, create a new object and replace the existing one.
17type ResourceInstanceObject struct {
18	// Value is the object-typed value representing the remote object within
19	// Terraform.
20	Value cty.Value
21
22	// Private is an opaque value set by the provider when this object was
23	// last created or updated. Terraform Core does not use this value in
24	// any way and it is not exposed anywhere in the user interface, so
25	// a provider can use it for retaining any necessary private state.
26	Private []byte
27
28	// Status represents the "readiness" of the object as of the last time
29	// it was updated.
30	Status ObjectStatus
31
32	// Dependencies is a set of other addresses in the same module which
33	// this instance depended on when the given attributes were evaluated.
34	// This is used to construct the dependency relationships for an object
35	// whose configuration is no longer available, such as if it has been
36	// removed from configuration altogether, or is now deposed.
37	Dependencies []addrs.Referenceable
38}
39
40// ObjectStatus represents the status of a RemoteObject.
41type ObjectStatus rune
42
43//go:generate go run golang.org/x/tools/cmd/stringer -type ObjectStatus
44
45const (
46	// ObjectReady is an object status for an object that is ready to use.
47	ObjectReady ObjectStatus = 'R'
48
49	// ObjectTainted is an object status representing an object that is in
50	// an unrecoverable bad state due to a partial failure during a create,
51	// update, or delete operation. Since it cannot be moved into the
52	// ObjectRead state, a tainted object must be replaced.
53	ObjectTainted ObjectStatus = 'T'
54
55	// ObjectPlanned is a special object status used only for the transient
56	// placeholder objects we place into state during the refresh and plan
57	// walks to stand in for objects that will be created during apply.
58	//
59	// Any object of this status must have a corresponding change recorded
60	// in the current plan, whose value must then be used in preference to
61	// the value stored in state when evaluating expressions. A planned
62	// object stored in state will be incomplete if any of its attributes are
63	// not yet known, and the plan must be consulted in order to "see" those
64	// unknown values, because the state is not able to represent them.
65	ObjectPlanned ObjectStatus = 'P'
66)
67
68// Encode marshals the value within the receiver to produce a
69// ResourceInstanceObjectSrc ready to be written to a state file.
70//
71// The given type must be the implied type of the resource type schema, and
72// the given value must conform to it. It is important to pass the schema
73// type and not the object's own type so that dynamically-typed attributes
74// will be stored correctly. The caller must also provide the version number
75// of the schema that the given type was derived from, which will be recorded
76// in the source object so it can be used to detect when schema migration is
77// required on read.
78//
79// The returned object may share internal references with the receiver and
80// so the caller must not mutate the receiver any further once once this
81// method is called.
82func (o *ResourceInstanceObject) Encode(ty cty.Type, schemaVersion uint64) (*ResourceInstanceObjectSrc, error) {
83	// Our state serialization can't represent unknown values, so we convert
84	// them to nulls here. This is lossy, but nobody should be writing unknown
85	// values here and expecting to get them out again later.
86	//
87	// We get unknown values here while we're building out a "planned state"
88	// during the plan phase, but the value stored in the plan takes precedence
89	// for expression evaluation. The apply step should never produce unknown
90	// values, but if it does it's the responsibility of the caller to detect
91	// and raise an error about that.
92	val := cty.UnknownAsNull(o.Value)
93
94	src, err := ctyjson.Marshal(val, ty)
95	if err != nil {
96		return nil, err
97	}
98
99	return &ResourceInstanceObjectSrc{
100		SchemaVersion: schemaVersion,
101		AttrsJSON:     src,
102		Private:       o.Private,
103		Status:        o.Status,
104		Dependencies:  o.Dependencies,
105	}, nil
106}
107
108// AsTainted returns a deep copy of the receiver with the status updated to
109// ObjectTainted.
110func (o *ResourceInstanceObject) AsTainted() *ResourceInstanceObject {
111	if o == nil {
112		// A nil object can't be tainted, but we'll allow this anyway to
113		// avoid a crash, since we presumably intend to eventually record
114		// the object has having been deleted anyway.
115		return nil
116	}
117	ret := o.DeepCopy()
118	ret.Status = ObjectTainted
119	return ret
120}
121