terraform/internal/repl/session.go

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package repl
import (
"strings"
"github.com/zclconf/go-cty/cty"
"github.com/hashicorp/hcl/v2"
"github.com/hashicorp/hcl/v2/hclsyntax"
"github.com/hashicorp/terraform/lang"
"github.com/hashicorp/terraform/tfdiags"
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)
// 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
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}
// 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) {
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switch {
case strings.TrimSpace(line) == "":
return "", false, nil
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case strings.TrimSpace(line) == "exit":
return "", true, nil
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case strings.TrimSpace(line) == "help":
ret, diags := s.handleHelp()
return ret, false, diags
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default:
ret, diags := s.handleEval(line)
return ret, false, diags
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}
}
func (s *Session) handleEval(line string) (string, tfdiags.Diagnostics) {
var diags tfdiags.Diagnostics
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// 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
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}
val, valDiags := s.Scope.EvalExpr(expr, cty.DynamicPseudoType)
diags = diags.Append(valDiags)
if valDiags.HasErrors() {
return "", diags
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}
return FormatValue(val, 0), diags
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}
func (s *Session) handleHelp() (string, tfdiags.Diagnostics) {
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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
}