terraform/states/instance_object_src.go

119 lines
4.8 KiB
Go

package states
import (
"github.com/zclconf/go-cty/cty"
ctyjson "github.com/zclconf/go-cty/cty/json"
"github.com/hashicorp/terraform/addrs"
"github.com/hashicorp/terraform/configs/hcl2shim"
)
// ResourceInstanceObjectSrc is a not-fully-decoded version of
// ResourceInstanceObject. Decoding of it can be completed by first handling
// any schema migration steps to get to the latest schema version and then
// calling method Decode with the implied type of the latest schema.
type ResourceInstanceObjectSrc struct {
// SchemaVersion is the resource-type-specific schema version number that
// was current when either AttrsJSON or AttrsFlat was encoded. Migration
// steps are required if this is less than the current version number
// reported by the corresponding provider.
SchemaVersion uint64
// AttrsJSON is a JSON-encoded representation of the object attributes,
// encoding the value (of the object type implied by the associated resource
// type schema) that represents this remote object in Terraform Language
// expressions, and is compared with configuration when producing a diff.
//
// This is retained in JSON format here because it may require preprocessing
// before decoding if, for example, the stored attributes are for an older
// schema version which the provider must upgrade before use. If the
// version is current, it is valid to simply decode this using the
// type implied by the current schema, without the need for the provider
// to perform an upgrade first.
//
// When writing a ResourceInstanceObject into the state, AttrsJSON should
// always be conformant to the current schema version and the current
// schema version should be recorded in the SchemaVersion field.
AttrsJSON []byte
// AttrsFlat is a legacy form of attributes used in older state file
// formats, and in the new state format for objects that haven't yet been
// upgraded. This attribute is mutually exclusive with Attrs: for any
// ResourceInstanceObject, only one of these attributes may be populated
// and the other must be nil.
//
// An instance object with this field populated should be upgraded to use
// Attrs at the earliest opportunity, since this legacy flatmap-based
// format will be phased out over time. AttrsFlat should not be used when
// writing new or updated objects to state; instead, callers must follow
// the recommendations in the AttrsJSON documentation above.
AttrsFlat map[string]string
// These fields all correspond to the fields of the same name on
// ResourceInstanceObject.
Private []byte
Status ObjectStatus
Dependencies []addrs.AbsResource
CreateBeforeDestroy bool
// deprecated
DependsOn []addrs.Referenceable
}
// Decode unmarshals the raw representation of the object attributes. Pass the
// implied type of the corresponding resource type schema for correct operation.
//
// Before calling Decode, the caller must check that the SchemaVersion field
// exactly equals the version number of the schema whose implied type is being
// passed, or else the result is undefined.
//
// The returned object may share internal references with the receiver and
// so the caller must not mutate the receiver any further once once this
// method is called.
func (os *ResourceInstanceObjectSrc) Decode(ty cty.Type) (*ResourceInstanceObject, error) {
var val cty.Value
var err error
if os.AttrsFlat != nil {
// Legacy mode. We'll do our best to unpick this from the flatmap.
val, err = hcl2shim.HCL2ValueFromFlatmap(os.AttrsFlat, ty)
if err != nil {
return nil, err
}
} else {
val, err = ctyjson.Unmarshal(os.AttrsJSON, ty)
if err != nil {
return nil, err
}
}
return &ResourceInstanceObject{
Value: val,
Status: os.Status,
Dependencies: os.Dependencies,
DependsOn: os.DependsOn,
Private: os.Private,
CreateBeforeDestroy: os.CreateBeforeDestroy,
}, nil
}
// CompleteUpgrade creates a new ResourceInstanceObjectSrc by copying the
// metadata from the receiver and writing in the given new schema version
// and attribute value that are presumed to have resulted from upgrading
// from an older schema version.
func (os *ResourceInstanceObjectSrc) CompleteUpgrade(newAttrs cty.Value, newType cty.Type, newSchemaVersion uint64) (*ResourceInstanceObjectSrc, error) {
new := os.DeepCopy()
new.AttrsFlat = nil // We always use JSON after an upgrade, even if the source used flatmap
// This is the same principle as ResourceInstanceObject.Encode, but
// avoiding a decode/re-encode cycle because we don't have type info
// available for the "old" attributes.
newAttrs = cty.UnknownAsNull(newAttrs)
src, err := ctyjson.Marshal(newAttrs, newType)
if err != nil {
return nil, err
}
new.AttrsJSON = src
new.SchemaVersion = newSchemaVersion
return new, nil
}