opentofu/repl/session.go
Alisdair McDiarmid 8b2b569d6e repl: Improved value renderer for console outputs
Use a slightly modified value renderer from terraform-provider-testing
to display values in the console REPL, as well as outputs from the apply
and outputs subcommands.

Derived from code in this repository, MIT licensed:

https://github.com/apparentlymart/terraform-provider-testing

Note that this is technically a breaking change for the console
subcommand, which would previously error if the user attempted to render
an unknown value (such as an unset variable). This was marked as an
unintentional side effect, with the goal being the new behaviour of
rendering "(unknown)", which is why I changed the behaviour in this
commit.
2020-09-14 09:47:12 -04:00

80 lines
2.2 KiB
Go

package repl
import (
"errors"
"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"
)
// 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
}
return FormatValue(val, 0), 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
}