package schema
import (
"errors"
"fmt"
"log"
"strconv"
"github.com/hashicorp/terraform/config"
"github.com/hashicorp/terraform/terraform"
)
// Resource represents a thing in Terraform that has a set of configurable
// attributes and a lifecycle (create, read, update, delete).
//
// The Resource schema is an abstraction that allows provider writers to
// worry only about CRUD operations while off-loading validation, diff
// generation, etc. to this higher level library.
//
// In spite of the name, this struct is not used only for terraform resources,
// but also for data sources. In the case of data sources, the Create,
// Update and Delete functions must not be provided.
type Resource struct {
// Schema is the schema for the configuration of this resource.
//
// The keys of this map are the configuration keys, and the values
// describe the schema of the configuration value.
//
// The schema is used to represent both configurable data as well
// as data that might be computed in the process of creating this
// resource.
Schema map[string]*Schema
// SchemaVersion is the version number for this resource's Schema
// definition. The current SchemaVersion stored in the state for each
// resource. Provider authors can increment this version number
// when Schema semantics change. If the State's SchemaVersion is less than
// the current SchemaVersion, the InstanceState is yielded to the
// MigrateState callback, where the provider can make whatever changes it
// needs to update the state to be compatible to the latest version of the
// Schema.
//
// When unset, SchemaVersion defaults to 0, so provider authors can start
// their Versioning at any integer >= 1
SchemaVersion int
// MigrateState is responsible for updating an InstanceState with an old
// version to the format expected by the current version of the Schema.
//
// It is called during Refresh if the State's stored SchemaVersion is less
// than the current SchemaVersion of the Resource.
//
// The function is yielded the state's stored SchemaVersion and a pointer to
// the InstanceState that needs updating, as well as the configured
// provider's configured meta interface{}, in case the migration process
// needs to make any remote API calls.
MigrateState StateMigrateFunc
// The functions below are the CRUD operations for this resource.
//
// The only optional operation is Update. If Update is not implemented,
// then updates will not be supported for this resource.
//
// The ResourceData parameter in the functions below are used to
// query configuration and changes for the resource as well as to set
// the ID, computed data, etc.
//
// The interface{} parameter is the result of the ConfigureFunc in
// the provider for this resource. If the provider does not define
// a ConfigureFunc, this will be nil. This parameter should be used
// to store API clients, configuration structures, etc.
//
// If any errors occur during each of the operation, an error should be
// returned. If a resource was partially updated, be careful to enable
// partial state mode for ResourceData and use it accordingly.
//
// Exists is a function that is called to check if a resource still
// exists. If this returns false, then this will affect the diff
// accordingly. If this function isn't set, it will not be called. It
// is highly recommended to set it. The *ResourceData passed to Exists
// should _not_ be modified.
Create CreateFunc
Read ReadFunc
Update UpdateFunc
Delete DeleteFunc
Exists ExistsFunc
// CustomizeDiff is a custom function for working with the diff that
// Terraform has created for this resource - it can be used to customize the
// diff that has been created, diff values not controlled by configuration,
// or even veto the diff altogether and abort the plan. It is passed a
// *ResourceDiff, a structure similar to ResourceData but lacking most write
// functions like Set, while introducing new functions that work with the
// diff such as SetNew, SetNewComputed, and ForceNew.
//
// The phases Terraform runs this in, and the state available via functions
// like Get and GetChange, are as follows:
//
// * New resource: One run with no state
// * Existing resource: One run with state
// * Existing resource, forced new: One run with state (before ForceNew),
// then one run without state (as if new resource)
// * Tainted resource: No runs (custom diff logic is skipped)
// * Destroy: No runs (standard diff logic is skipped on destroy diffs)
//
// This function needs to be resilient to support all scenarios.
//
// If this function needs to access external API resources, remember to flag
// the RequiresRefresh attribute mentioned below to ensure that
// -refresh=false is blocked when running plan or apply, as this means that
// this resource requires refresh-like behaviour to work effectively.
//
// For the most part, only computed fields can be customized by this
// function.
//
// This function is only allowed on regular resources (not data sources).
CustomizeDiff CustomizeDiffFunc
// Importer is the ResourceImporter implementation for this resource.
// If this is nil, then this resource does not support importing. If
// this is non-nil, then it supports importing and ResourceImporter
// must be validated. The validity of ResourceImporter is verified
// by InternalValidate on Resource.
Importer *ResourceImporter
// If non-empty, this string is emitted as a warning during Validate.
DeprecationMessage string
// Timeouts allow users to specify specific time durations in which an
// operation should time out, to allow them to extend an action to suit their
// usage. For example, a user may specify a large Creation timeout for their
// AWS RDS Instance due to it's size, or restoring from a snapshot.
// Resource implementors must enable Timeout support by adding the allowed
// actions (Create, Read, Update, Delete, Default) to the Resource struct, and
// accessing them in the matching methods.
Timeouts *ResourceTimeout
}
// See Resource documentation.
type CreateFunc func(*ResourceData, interface{}) error
// See Resource documentation.
type ReadFunc func(*ResourceData, interface{}) error
// See Resource documentation.
type UpdateFunc func(*ResourceData, interface{}) error
// See Resource documentation.
type DeleteFunc func(*ResourceData, interface{}) error
// See Resource documentation.
type ExistsFunc func(*ResourceData, interface{}) (bool, error)
// See Resource documentation.
type StateMigrateFunc func(
int, *terraform.InstanceState, interface{}) (*terraform.InstanceState, error)
// See Resource documentation.
type CustomizeDiffFunc func(*ResourceDiff, interface{}) error
// Apply creates, updates, and/or deletes a resource.
func (r *Resource) Apply(
s *terraform.InstanceState,
d *terraform.InstanceDiff,
meta interface{}) (*terraform.InstanceState, error) {
data, err := schemaMap(r.Schema).Data(s, d)
if err != nil {
return s, err
}
// Instance Diff shoould have the timeout info, need to copy it over to the
// ResourceData meta
rt := ResourceTimeout{}
if _, ok := d.Meta[TimeoutKey]; ok {
if err := rt.DiffDecode(d); err != nil {
log.Printf("[ERR] Error decoding ResourceTimeout: %s", err)
}
} else if s != nil {
if _, ok := s.Meta[TimeoutKey]; ok {
if err := rt.StateDecode(s); err != nil {
log.Printf("[ERR] Error decoding ResourceTimeout: %s", err)
}
}
} else {
log.Printf("[DEBUG] No meta timeoutkey found in Apply()")
}
data.timeouts = &rt
if s == nil {
// The Terraform API dictates that this should never happen, but
// it doesn't hurt to be safe in this case.
s = new(terraform.InstanceState)
}
if d.Destroy || d.RequiresNew() {
if s.ID != "" {
// Destroy the resource since it is created
if err := r.Delete(data, meta); err != nil {
return r.recordCurrentSchemaVersion(data.State()), err
}
// Make sure the ID is gone.
data.SetId("")
}
// If we're only destroying, and not creating, then return
// now since we're done!
if !d.RequiresNew() {
return nil, nil
}
// Reset the data to be stateless since we just destroyed
data, err = schemaMap(r.Schema).Data(nil, d)
// data was reset, need to re-apply the parsed timeouts
data.timeouts = &rt
if err != nil {
return nil, err
}
}
err = nil
if data.Id() == "" {
// We're creating, it is a new resource.
data.MarkNewResource()
err = r.Create(data, meta)
} else {
if r.Update == nil {
return s, fmt.Errorf("doesn't support update")
}
err = r.Update(data, meta)
}
return r.recordCurrentSchemaVersion(data.State()), err
}
// Diff returns a diff of this resource.
func (r *Resource) Diff(
s *terraform.InstanceState,
c *terraform.ResourceConfig,
meta interface{}) (*terraform.InstanceDiff, error) {
t := &ResourceTimeout{}
err := t.ConfigDecode(r, c)
if err != nil {
return nil, fmt.Errorf("[ERR] Error decoding timeout: %s", err)
}
instanceDiff, err := schemaMap(r.Schema).Diff(s, c, r.CustomizeDiff, meta)
if err != nil {
return instanceDiff, err
}
if instanceDiff != nil {
if err := t.DiffEncode(instanceDiff); err != nil {
log.Printf("[ERR] Error encoding timeout to instance diff: %s", err)
}
} else {
log.Printf("[DEBUG] Instance Diff is nil in Diff()")
}
return instanceDiff, err
}
// Validate validates the resource configuration against the schema.
func (r *Resource) Validate(c *terraform.ResourceConfig) ([]string, []error) {
warns, errs := schemaMap(r.Schema).Validate(c)
if r.DeprecationMessage != "" {
warns = append(warns, r.DeprecationMessage)
}
return warns, errs
}
// ReadDataApply loads the data for a data source, given a diff that
// describes the configuration arguments and desired computed attributes.
func (r *Resource) ReadDataApply(
d *terraform.InstanceDiff,
meta interface{},
) (*terraform.InstanceState, error) {
// Data sources are always built completely from scratch
// on each read, so the source state is always nil.
data, err := schemaMap(r.Schema).Data(nil, d)
if err != nil {
return nil, err
}
err = r.Read(data, meta)
state := data.State()
if state != nil && state.ID == "" {
// Data sources can set an ID if they want, but they aren't
// required to; we'll provide a placeholder if they don't,
// to preserve the invariant that all resources have non-empty
// ids.
state.ID = "-"
}
return r.recordCurrentSchemaVersion(state), err
}
// Refresh refreshes the state of the resource.
func (r *Resource) Refresh(
s *terraform.InstanceState,
meta interface{}) (*terraform.InstanceState, error) {
// If the ID is already somehow blank, it doesn't exist
if s.ID == "" {
return nil, nil
}
rt := ResourceTimeout{}
if _, ok := s.Meta[TimeoutKey]; ok {
if err := rt.StateDecode(s); err != nil {
log.Printf("[ERR] Error decoding ResourceTimeout: %s", err)
}
}
if r.Exists != nil {
// Make a copy of data so that if it is modified it doesn't
// affect our Read later.
data, err := schemaMap(r.Schema).Data(s, nil)
data.timeouts = &rt
if err != nil {
return s, err
}
exists, err := r.Exists(data, meta)
if err != nil {
return s, err
}
if !exists {
return nil, nil
}
}
needsMigration, stateSchemaVersion := r.checkSchemaVersion(s)
if needsMigration && r.MigrateState != nil {
s, err := r.MigrateState(stateSchemaVersion, s, meta)
if err != nil {
return s, err
}
}
data, err := schemaMap(r.Schema).Data(s, nil)
data.timeouts = &rt
if err != nil {
return s, err
}
err = r.Read(data, meta)
state := data.State()
if state != nil && state.ID == "" {
state = nil
}
return r.recordCurrentSchemaVersion(state), err
}
// InternalValidate should be called to validate the structure
// of the resource.
//
// This should be called in a unit test for any resource to verify
// before release that a resource is properly configured for use with
// this library.
//
// Provider.InternalValidate() will automatically call this for all of
// the resources it manages, so you don't need to call this manually if it
// is part of a Provider.
func (r *Resource) InternalValidate(topSchemaMap schemaMap, writable bool) error {
if r == nil {
return errors.New("resource is nil")
}
if !writable {
if r.Create != nil || r.Update != nil || r.Delete != nil {
return fmt.Errorf("must not implement Create, Update or Delete")
}
// CustomizeDiff cannot be defined for read-only resources
if r.CustomizeDiff != nil {
return fmt.Errorf("cannot implement CustomizeDiff")
}
}
tsm := topSchemaMap
if r.isTopLevel() && writable {
// All non-Computed attributes must be ForceNew if Update is not defined
if r.Update == nil {
nonForceNewAttrs := make([]string, 0)
for k, v := range r.Schema {
if !v.ForceNew && !v.Computed {
nonForceNewAttrs = append(nonForceNewAttrs, k)
}
}
if len(nonForceNewAttrs) > 0 {
return fmt.Errorf(
"No Update defined, must set ForceNew on: %#v", nonForceNewAttrs)
}
} else {
nonUpdateableAttrs := make([]string, 0)
for k, v := range r.Schema {
if v.ForceNew || v.Computed && !v.Optional {
nonUpdateableAttrs = append(nonUpdateableAttrs, k)
}
}
updateableAttrs := len(r.Schema) - len(nonUpdateableAttrs)
if updateableAttrs == 0 {
return fmt.Errorf(
"All fields are ForceNew or Computed w/out Optional, Update is superfluous")
}
}
tsm = schemaMap(r.Schema)
// Destroy, and Read are required
if r.Read == nil {
return fmt.Errorf("Read must be implemented")
}
if r.Delete == nil {
return fmt.Errorf("Delete must be implemented")
}
// If we have an importer, we need to verify the importer.
if r.Importer != nil {
if err := r.Importer.InternalValidate(); err != nil {
return err
}
}
for k, f := range tsm {
if isReservedResourceFieldName(k, f) {
return fmt.Errorf("%s is a reserved field name", k)
}
}
}
// Data source
if r.isTopLevel() && !writable {
tsm = schemaMap(r.Schema)
for k, _ := range tsm {
if isReservedDataSourceFieldName(k) {
return fmt.Errorf("%s is a reserved field name", k)
}
}
}
return schemaMap(r.Schema).InternalValidate(tsm)
}
func isReservedDataSourceFieldName(name string) bool {
for _, reservedName := range config.ReservedDataSourceFields {
if name == reservedName {
return true
}
}
return false
}
func isReservedResourceFieldName(name string, s *Schema) bool {
// Allow phasing out "id"
// See https://github.com/terraform-providers/terraform-provider-aws/pull/1626#issuecomment-328881415
if name == "id" && (s.Deprecated != "" || s.Removed != "") {
return false
}
for _, reservedName := range config.ReservedResourceFields {
if name == reservedName {
return true
}
}
return false
}
// Data returns a ResourceData struct for this Resource. Each return value
// is a separate copy and can be safely modified differently.
//
// The data returned from this function has no actual affect on the Resource
// itself (including the state given to this function).
//
// This function is useful for unit tests and ResourceImporter functions.
func (r *Resource) Data(s *terraform.InstanceState) *ResourceData {
result, err := schemaMap(r.Schema).Data(s, nil)
if err != nil {
// At the time of writing, this isn't possible (Data never returns
// non-nil errors). We panic to find this in the future if we have to.
// I don't see a reason for Data to ever return an error.
panic(err)
}
// load the Resource timeouts
result.timeouts = r.Timeouts
if result.timeouts == nil {
result.timeouts = &ResourceTimeout{}
}
// Set the schema version to latest by default
result.meta = map[string]interface{}{
"schema_version": strconv.Itoa(r.SchemaVersion),
}
return result
}
// TestResourceData Yields a ResourceData filled with this resource's schema for use in unit testing
//
// TODO: May be able to be removed with the above ResourceData function.
func (r *Resource) TestResourceData() *ResourceData {
return &ResourceData{
schema: r.Schema,
}
}
// Returns true if the resource is "top level" i.e. not a sub-resource.
func (r *Resource) isTopLevel() bool {
// TODO: This is a heuristic; replace with a definitive attribute?
return (r.Create != nil || r.Read != nil)
}
// Determines if a given InstanceState needs to be migrated by checking the
// stored version number with the current SchemaVersion
func (r *Resource) checkSchemaVersion(is *terraform.InstanceState) (bool, int) {
// Get the raw interface{} value for the schema version. If it doesn't
// exist or is nil then set it to zero.
raw := is.Meta["schema_version"]
if raw == nil {
raw = "0"
}
// Try to convert it to a string. If it isn't a string then we pretend
// that it isn't set at all. It should never not be a string unless it
// was manually tampered with.
rawString, ok := raw.(string)
if !ok {
rawString = "0"
}
stateSchemaVersion, _ := strconv.Atoi(rawString)
return stateSchemaVersion < r.SchemaVersion, stateSchemaVersion
}
func (r *Resource) recordCurrentSchemaVersion(
state *terraform.InstanceState) *terraform.InstanceState {
if state != nil && r.SchemaVersion > 0 {
if state.Meta == nil {
state.Meta = make(map[string]interface{})
}
state.Meta["schema_version"] = strconv.Itoa(r.SchemaVersion)
}
return state
}
// Noop is a convenience implementation of resource function which takes
// no action and returns no error.
func Noop(*ResourceData, interface{}) error {
return nil
}
// RemoveFromState is a convenience implementation of a resource function
// which sets the resource ID to empty string (to remove it from state)
// and returns no error.
func RemoveFromState(d *ResourceData, _ interface{}) error {
d.SetId("")
return nil
}