opentofu/terraform/eval_context.go
Martin Atkins 73053eb5ef core: Context.Eval method
Some of the objects that are referencable from expressions are transient
values computed only during a graph walk, and not persisted in state. In
order to support arbitrary evaluation of expressions, such as in the
"terraform console" CLI command, it's necessary to be able to evaluate
these values before we start evaluating.

This new Eval method achieves this by performing a special graph walk that
ignores resources (except for dependency resolution) and just focuses on
evaluating all of these transient values, before returning an evaluation
scope that can then resolve expressions in terms of that result.

This replaces the Context.Interpolator method, which was fraught with
various issues due to it not properly priming the state before evaluating.
2018-10-16 18:46:46 -07:00

132 lines
5.6 KiB
Go

package terraform
import (
"sync"
"github.com/hashicorp/hcl2/hcl"
"github.com/hashicorp/terraform/addrs"
"github.com/hashicorp/terraform/config/configschema"
"github.com/hashicorp/terraform/lang"
"github.com/hashicorp/terraform/tfdiags"
"github.com/zclconf/go-cty/cty"
)
// EvalContext is the interface that is given to eval nodes to execute.
type EvalContext interface {
// Stopped returns a channel that is closed when evaluation is stopped
// via Terraform.Context.Stop()
Stopped() <-chan struct{}
// Path is the current module path.
Path() addrs.ModuleInstance
// Hook is used to call hook methods. The callback is called for each
// hook and should return the hook action to take and the error.
Hook(func(Hook) (HookAction, error)) error
// Input is the UIInput object for interacting with the UI.
Input() UIInput
// InitProvider initializes the provider with the given type and address, and
// returns the implementation of the resource provider or an error.
//
// It is an error to initialize the same provider more than once.
InitProvider(typ string, addr addrs.ProviderConfig) (ResourceProvider, error)
// Provider gets the provider instance with the given address (already
// initialized) or returns nil if the provider isn't initialized.
//
// This method expects an _absolute_ provider configuration address, since
// resources in one module are able to use providers from other modules.
// InitProvider must've been called on the EvalContext of the module
// that owns the given provider before calling this method.
Provider(addrs.AbsProviderConfig) ResourceProvider
// ProviderSchema retrieves the schema for a particular provider, which
// must have already been initialized with InitProvider.
//
// This method expects an _absolute_ provider configuration address, since
// resources in one module are able to use providers from other modules.
ProviderSchema(addrs.AbsProviderConfig) *ProviderSchema
// CloseProvider closes provider connections that aren't needed anymore.
CloseProvider(addrs.ProviderConfig) error
// ConfigureProvider configures the provider with the given
// configuration. This is a separate context call because this call
// is used to store the provider configuration for inheritance lookups
// with ParentProviderConfig().
ConfigureProvider(addrs.ProviderConfig, cty.Value) tfdiags.Diagnostics
// ProviderInput and SetProviderInput are used to configure providers
// from user input.
ProviderInput(addrs.ProviderConfig) map[string]cty.Value
SetProviderInput(addrs.ProviderConfig, map[string]cty.Value)
// InitProvisioner initializes the provisioner with the given name and
// returns the implementation of the resource provisioner or an error.
//
// It is an error to initialize the same provisioner more than once.
InitProvisioner(string) (ResourceProvisioner, error)
// Provisioner gets the provisioner instance with the given name (already
// initialized) or returns nil if the provisioner isn't initialized.
Provisioner(string) ResourceProvisioner
// ProvisionerSchema retrieves the main configuration schema for a
// particular provisioner, which must have already been initialized with
// InitProvisioner.
ProvisionerSchema(string) *configschema.Block
// CloseProvisioner closes provisioner connections that aren't needed
// anymore.
CloseProvisioner(string) error
// EvaluateBlock takes the given raw configuration block and associated
// schema and evaluates it to produce a value of an object type that
// conforms to the implied type of the schema.
//
// The "self" argument is optional. If given, it is the referenceable
// address that the name "self" should behave as an alias for when
// evaluating. Set this to nil if the "self" object should not be available.
//
// The "key" argument is also optional. If given, it is the instance key
// of the current object within the multi-instance container it belongs
// to. For example, on a resource block with "count" set this should be
// set to a different addrs.IntKey for each instance created from that
// block. Set this to addrs.NoKey if not appropriate.
//
// The returned body is an expanded version of the given body, with any
// "dynamic" blocks replaced with zero or more static blocks. This can be
// used to extract correct source location information about attributes of
// the returned object value.
EvaluateBlock(body hcl.Body, schema *configschema.Block, self addrs.Referenceable, key addrs.InstanceKey) (cty.Value, hcl.Body, tfdiags.Diagnostics)
// EvaluateExpr takes the given HCL expression and evaluates it to produce
// a value.
//
// The "self" argument is optional. If given, it is the referenceable
// address that the name "self" should behave as an alias for when
// evaluating. Set this to nil if the "self" object should not be available.
EvaluateExpr(expr hcl.Expression, wantType cty.Type, self addrs.Referenceable) (cty.Value, tfdiags.Diagnostics)
// EvaluationScope returns a scope that can be used to evaluate reference
// addresses in this context.
EvaluationScope(self addrs.Referenceable, key addrs.InstanceKey) *lang.Scope
// SetModuleCallArguments defines values for the variables of a particular
// child module call.
//
// Calling this function multiple times has merging behavior, keeping any
// previously-set keys that are not present in the new map.
SetModuleCallArguments(addrs.ModuleCallInstance, map[string]cty.Value)
// Diff returns the global diff as well as the lock that should
// be used to modify that diff.
Diff() (*Diff, *sync.RWMutex)
// State returns the global state as well as the lock that should
// be used to modify that state.
State() (*State, *sync.RWMutex)
}