package schema import ( "context" "github.com/hashicorp/terraform/terraform" ) // Backend represents a partial backend.Backend implementation and simplifies // the creation of configuration loading and validation. // // Unlike other schema structs such as Provider, this struct is meant to be // embedded within your actual implementation. It provides implementations // only for Input and Configure and gives you a method for accessing the // configuration in the form of a ResourceData that you're expected to call // from the other implementation funcs. type Backend struct { // Schema is the schema for the configuration of this backend. If this // Backend has no configuration this can be omitted. Schema map[string]*Schema // ConfigureFunc is called to configure the backend. Use the // FromContext* methods to extract information from the context. // This can be nil, in which case nothing will be called but the // config will still be stored. ConfigureFunc func(context.Context) error config *ResourceData } var ( backendConfigKey = contextKey("backend config") ) // FromContextBackendConfig extracts a ResourceData with the configuration // from the context. This should only be called by Backend functions. func FromContextBackendConfig(ctx context.Context) *ResourceData { return ctx.Value(backendConfigKey).(*ResourceData) } func (b *Backend) Input( input terraform.UIInput, c *terraform.ResourceConfig) (*terraform.ResourceConfig, error) { if b == nil { return c, nil } return schemaMap(b.Schema).Input(input, c) } func (b *Backend) Validate(c *terraform.ResourceConfig) ([]string, []error) { if b == nil { return nil, nil } return schemaMap(b.Schema).Validate(c) } func (b *Backend) Configure(c *terraform.ResourceConfig) error { if b == nil { return nil } sm := schemaMap(b.Schema) // Get a ResourceData for this configuration. To do this, we actually // generate an intermediary "diff" although that is never exposed. diff, err := sm.Diff(nil, c, nil, nil) if err != nil { return err } data, err := sm.Data(nil, diff) if err != nil { return err } b.config = data if b.ConfigureFunc != nil { err = b.ConfigureFunc(context.WithValue( context.Background(), backendConfigKey, data)) if err != nil { return err } } return nil } // Config returns the configuration. This is available after Configure is // called. func (b *Backend) Config() *ResourceData { return b.config }