opentofu/repl/session.go
2019-08-06 19:58:58 -04:00

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/configs/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
}