command: move inspect to schedulers

command/inspect.go

@@ -7,7 +7,6 @@ import (
 	"context"
 	"strings"
 
-	"github.com/hashicorp/packer/packer"
 	"github.com/posener/complete"
 )
 
@@ -48,12 +47,7 @@ func (c *InspectCommand) RunContext(ctx context.Context, cla *InspectArgs) int {
 		return ret
 	}
 
-	// here we ignore init diags to allow unknown variables to be used
-	_ = packerStarter.Initialize(packer.InitializeOptions{})
-
-	return packerStarter.InspectConfig(packer.InspectConfigOptions{
-		Ui: c.Ui,
-	})
+	return NewScheduler(packerStarter, c.Ui, ctx).Inspect(cla)
 }
 
 func (*InspectCommand) Help() string {

command/scheduler.go

@@ -10,6 +10,7 @@ import (
 type Scheduler interface {
 	Build(*BuildArgs) int
 	Validate(*ValidateArgs) int
+	Inspect(*InspectArgs) int
 }
 
 // NewScheduler returns a new scheduler for running commands with.

command/sequential_scheduler.go

@@ -77,7 +77,13 @@ func (s *SequentialScheduler) prepare(skipDatasourcesExecution bool) hcl.Diagnos
 	diags = diags.Extend(s.scheduler.PrepareBuilds())
 
 	return diags
+}
 
+func (s *SequentialScheduler) Inspect(args *InspectArgs) int {
+	s.prepare(false)
+	return s.handler.InspectConfig(packer.InspectConfigOptions{
+		Ui: s.ui,
+	})
 }
 
 func (s *SequentialScheduler) Validate(args *ValidateArgs) int {