[github/fretlink/terraform-provider-statuscake.git] / vendor / github.com / hashicorp / terraform / helper / schema / resource.go

package schema

import (
        "errors"
        "fmt"
        "log"
        "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

        // 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)

// 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 {
                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 and is API compatible with the
// ResourceProvider interface.
func (r *Resource) Diff(
        s *terraform.InstanceState,
        c *terraform.ResourceConfig) (*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)
        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")
                }
        }

        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
                        }
                }
        }

        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]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
}

// 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
}