terraform/helper/schema/resource.go

387 lines
12 KiB
Go

package schema
import (
"errors"
"fmt"
"strconv"
"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
// 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.
// This is a private interface for now, for use by DataSourceResourceShim,
// and not for general use. (But maybe later...)
deprecationMessage string
}
// 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)
// 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
}
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)
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 and is API compatible with the
// ResourceProvider interface.
func (r *Resource) Diff(
s *terraform.InstanceState,
c *terraform.ResourceConfig) (*terraform.InstanceDiff, error) {
return schemaMap(r.Schema).Diff(s, c)
}
// 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
}
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)
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)
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")
}
}
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)
// If we have an importer, we need to verify the importer.
if r.Importer != nil {
if err := r.Importer.InternalValidate(); err != nil {
return err
}
}
}
return schemaMap(r.Schema).InternalValidate(tsm)
}
// 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)
}
// Set the schema version to latest by default
result.meta = map[string]string{
"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
}
// 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) {
stateSchemaVersion, _ := strconv.Atoi(is.Meta["schema_version"])
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]string)
}
state.Meta["schema_version"] = strconv.Itoa(r.SchemaVersion)
}
return state
}