terraform/states/resource.go

240 lines
7.5 KiB
Go

package states
import (
"fmt"
"math/rand"
"time"
"github.com/hashicorp/terraform/addrs"
)
// Resource represents the state of a resource.
type Resource struct {
// Addr is the module-relative address for the resource this state object
// belongs to.
Addr addrs.Resource
// EachMode is the multi-instance mode currently in use for this resource,
// or NoEach if this is a single-instance resource. This dictates what
// type of value is returned when accessing this resource via expressions
// in the Terraform language.
EachMode EachMode
// Instances contains the potentially-multiple instances associated with
// this resource. This map can contain a mixture of different key types,
// but only the ones of InstanceKeyType are considered current.
Instances map[addrs.InstanceKey]*ResourceInstance
// ProviderConfig is the absolute address for the provider configuration that
// most recently managed this resource. This is used to connect a resource
// with a provider configuration when the resource configuration block is
// not available, such as if it has been removed from configuration
// altogether.
ProviderConfig addrs.AbsProviderConfig
}
// Instance returns the state for the instance with the given key, or nil
// if no such instance is tracked within the state.
func (rs *Resource) Instance(key addrs.InstanceKey) *ResourceInstance {
return rs.Instances[key]
}
// EnsureInstance returns the state for the instance with the given key,
// creating a new empty state for it if one doesn't already exist.
//
// Because this may create and save a new state, it is considered to be
// a write operation.
func (rs *Resource) EnsureInstance(key addrs.InstanceKey) *ResourceInstance {
ret := rs.Instance(key)
if ret == nil {
ret = NewResourceInstance()
rs.Instances[key] = ret
}
return ret
}
// ResourceInstance represents the state of a particular instance of a resource.
type ResourceInstance struct {
// Current, if non-nil, is the remote object that is currently represented
// by the corresponding resource instance.
Current *ResourceInstanceObjectSrc
// Deposed, if len > 0, contains any remote objects that were previously
// represented by the corresponding resource instance but have been
// replaced and are pending destruction due to the create_before_destroy
// lifecycle mode.
Deposed map[DeposedKey]*ResourceInstanceObjectSrc
}
// NewResourceInstance constructs and returns a new ResourceInstance, ready to
// use.
func NewResourceInstance() *ResourceInstance {
return &ResourceInstance{
Deposed: map[DeposedKey]*ResourceInstanceObjectSrc{},
}
}
// HasCurrent returns true if this resource instance has a "current"-generation
// object. Most instances do, but this can briefly be false during a
// create-before-destroy replace operation when the current has been deposed
// but its replacement has not yet been created.
func (i *ResourceInstance) HasCurrent() bool {
return i != nil && i.Current != nil
}
// HasDeposed returns true if this resource instance has a deposed object
// with the given key.
func (i *ResourceInstance) HasDeposed(key DeposedKey) bool {
return i != nil && i.Deposed[key] != nil
}
// HasAnyDeposed returns true if this resource instance has one or more
// deposed objects.
func (i *ResourceInstance) HasAnyDeposed() bool {
return i != nil && len(i.Deposed) > 0
}
// HasObjects returns true if this resource has any objects at all, whether
// current or deposed.
func (i *ResourceInstance) HasObjects() bool {
return i.Current != nil || len(i.Deposed) != 0
}
// deposeCurrentObject is part of the real implementation of
// SyncState.DeposeResourceInstanceObject. The exported method uses a lock
// to ensure that we can safely allocate an unused deposed key without
// collision.
func (i *ResourceInstance) deposeCurrentObject(forceKey DeposedKey) DeposedKey {
if !i.HasCurrent() {
return NotDeposed
}
key := forceKey
if key == NotDeposed {
key = i.findUnusedDeposedKey()
} else {
if _, exists := i.Deposed[key]; exists {
panic(fmt.Sprintf("forced key %s is already in use", forceKey))
}
}
i.Deposed[key] = i.Current
i.Current = nil
return key
}
// GetGeneration retrieves the object of the given generation from the
// ResourceInstance, or returns nil if there is no such object.
//
// If the given generation is nil or invalid, this method will panic.
func (i *ResourceInstance) GetGeneration(gen Generation) *ResourceInstanceObjectSrc {
if gen == CurrentGen {
return i.Current
}
if dk, ok := gen.(DeposedKey); ok {
return i.Deposed[dk]
}
if gen == nil {
panic(fmt.Sprintf("get with nil Generation"))
}
// Should never fall out here, since the above covers all possible
// Generation values.
panic(fmt.Sprintf("get invalid Generation %#v", gen))
}
// FindUnusedDeposedKey generates a unique DeposedKey that is guaranteed not to
// already be in use for this instance at the time of the call.
//
// Note that the validity of this result may change if new deposed keys are
// allocated before it is used. To avoid this risk, instead use the
// DeposeResourceInstanceObject method on the SyncState wrapper type, which
// allocates a key and uses it atomically.
func (i *ResourceInstance) FindUnusedDeposedKey() DeposedKey {
return i.findUnusedDeposedKey()
}
// findUnusedDeposedKey generates a unique DeposedKey that is guaranteed not to
// already be in use for this instance.
func (i *ResourceInstance) findUnusedDeposedKey() DeposedKey {
for {
key := NewDeposedKey()
if _, exists := i.Deposed[key]; !exists {
return key
}
// Spin until we find a unique one. This shouldn't take long, because
// we have a 32-bit keyspace and there's rarely more than one deposed
// instance.
}
}
// EachMode specifies the multi-instance mode for a resource.
type EachMode rune
const (
NoEach EachMode = 0
EachList EachMode = 'L'
EachMap EachMode = 'M'
)
//go:generate stringer -type EachMode
func eachModeForInstanceKey(key addrs.InstanceKey) EachMode {
switch key.(type) {
case addrs.IntKey:
return EachList
case addrs.StringKey:
return EachMap
default:
if key == addrs.NoKey {
return NoEach
}
panic(fmt.Sprintf("don't know an each mode for instance key %#v", key))
}
}
// DeposedKey is a 8-character hex string used to uniquely identify deposed
// instance objects in the state.
type DeposedKey string
// NotDeposed is a special invalid value of DeposedKey that is used to represent
// the absense of a deposed key. It must not be used as an actual deposed key.
const NotDeposed = DeposedKey("")
var deposedKeyRand = rand.New(rand.NewSource(time.Now().UnixNano()))
// NewDeposedKey generates a pseudo-random deposed key. Because of the short
// length of these keys, uniqueness is not a natural consequence and so the
// caller should test to see if the generated key is already in use and generate
// another if so, until a unique key is found.
func NewDeposedKey() DeposedKey {
v := deposedKeyRand.Uint32()
return DeposedKey(fmt.Sprintf("%08x", v))
}
func (k DeposedKey) String() string {
return string(k)
}
func (k DeposedKey) GoString() string {
ks := string(k)
switch {
case ks == "":
return "states.NotDeposed"
default:
return fmt.Sprintf("states.DeposedKey(%s)", ks)
}
}
// Generation is a helper method to convert a DeposedKey into a Generation.
// If the reciever is anything other than NotDeposed then the result is
// just the same value as a Generation. If the receiver is NotDeposed then
// the result is CurrentGen.
func (k DeposedKey) Generation() Generation {
if k == NotDeposed {
return CurrentGen
}
return k
}
// generation is an implementation of Generation.
func (k DeposedKey) generation() {}