opentofu/repl/session.go
Martin Atkins f085af4ba6 command: update "terraform console" for HCL2
This now uses the HCL2 parser and evaluator APIs and evaluates in terms
of a new-style *lang.Scope, rather than the old terraform.Interpolator
type that is no longer functional.

The Context.Eval method used here behaves differently than the
Context.Interpolater method used previously: it performs a graph walk
to populate transient values such as input variables, local values, and
output values, and produces its scope in terms of the result of that
graph walk. Because of this, it is a lot more robust than the prior method
when asked to resolve references other than those that are persisted
in the state.
2018-10-16 18:46:46 -07:00

100 lines
3.0 KiB
Go

package repl
import (
"errors"
"fmt"
"strings"
"github.com/zclconf/go-cty/cty"
"github.com/hashicorp/hcl2/hcl"
"github.com/hashicorp/hcl2/hcl/hclsyntax"
"github.com/hashicorp/terraform/config/hcl2shim"
"github.com/hashicorp/terraform/lang"
"github.com/hashicorp/terraform/tfdiags"
)
// ErrSessionExit is a special error result that should be checked for
// from Handle to signal a graceful exit.
var ErrSessionExit = errors.New("session exit")
// Session represents the state for a single REPL session.
type Session struct {
// Scope is the evaluation scope where expressions will be evaluated.
Scope *lang.Scope
}
// Handle handles a single line of input from the REPL.
//
// This is a stateful operation if a command is given (such as setting
// a variable). This function should not be called in parallel.
//
// The return value is the output and the error to show.
func (s *Session) Handle(line string) (string, bool, tfdiags.Diagnostics) {
switch {
case strings.TrimSpace(line) == "":
return "", false, nil
case strings.TrimSpace(line) == "exit":
return "", true, nil
case strings.TrimSpace(line) == "help":
ret, diags := s.handleHelp()
return ret, false, diags
default:
ret, diags := s.handleEval(line)
return ret, false, diags
}
}
func (s *Session) handleEval(line string) (string, tfdiags.Diagnostics) {
var diags tfdiags.Diagnostics
// Parse the given line as an expression
expr, parseDiags := hclsyntax.ParseExpression([]byte(line), "<console-input>", hcl.Pos{Line: 1, Column: 1})
diags = diags.Append(parseDiags)
if parseDiags.HasErrors() {
return "", diags
}
val, valDiags := s.Scope.EvalExpr(expr, cty.DynamicPseudoType)
diags = diags.Append(valDiags)
if valDiags.HasErrors() {
return "", diags
}
if !val.IsWhollyKnown() {
// FIXME: In future, once we've updated the result formatter to be
// cty-aware, we should just include unknown values as "(not yet known)"
// in the serialized result, allowing the rest (if any) to be seen.
diags = diags.Append(fmt.Errorf("Result depends on values that cannot be determined until after \"terraform apply\"."))
return "", diags
}
// Our formatter still wants an old-style raw interface{} value, so
// for now we'll just shim it.
// FIXME: Port the formatter to work with cty.Value directly.
legacyVal := hcl2shim.ConfigValueFromHCL2(val)
result, err := FormatResult(legacyVal)
if err != nil {
diags = diags.Append(err)
return "", diags
}
return result, diags
}
func (s *Session) handleHelp() (string, tfdiags.Diagnostics) {
text := `
The Terraform console allows you to experiment with Terraform interpolations.
You may access resources in the state (if you have one) just as you would
from a configuration. For example: "aws_instance.foo.id" would evaluate
to the ID of "aws_instance.foo" if it exists in your state.
Type in the interpolation to test and hit <enter> to see the result.
To exit the console, type "exit" and hit <enter>, or use Control-C or
Control-D.
`
return strings.TrimSpace(text), nil
}