make ephemeral calls cancellable

internal/resources/ephemeral/ephemeral_resources.go

@@ -140,8 +140,11 @@ func (r *Resources) Close(ctx context.Context) tfdiags.Diagnostics {
 	r.mu.Lock()
 	defer r.mu.Unlock()
 
-	// We might be closing due to a context cancellation, but we still need
-	// to be able to make non-canceled Close requests.
+	// We might be closing due to a context cancellation, but we still need to
+	// be able to make non-canceled Close requests.
+	//
+	// TODO: if we're going to ignore the cancellation to ensure that Close is
+	// always called, should we add some sort of timeout?
 	ctx = context.WithoutCancel(ctx)
 
 	var diags tfdiags.Diagnostics

internal/terraform/eval_context_mock.go

@@ -168,7 +168,10 @@ var _ EvalContext = (*MockEvalContext)(nil)
 
 func (c *MockEvalContext) StopCtx() context.Context {
 	c.StopCtxCalled = true
-	return c.StopCtxValue
+	if c.StopCtxValue != nil {
+		return c.StopCtxValue
+	}
+	return context.TODO()
 }
 
 func (c *MockEvalContext) Hook(fn func(Hook) (HookAction, error)) error {

internal/terraform/node_module_expand.go

@@ -4,7 +4,6 @@
 package terraform
 
 import (
-	"context"
 	"log"
 
 	"github.com/hashicorp/terraform/internal/addrs"
@@ -215,7 +214,7 @@ func (n *nodeCloseModule) Execute(ctx EvalContext, op walkOperation) (diags tfdi
 	diags = diags.Append(ctx.ClosePlugins())
 
 	// We also close up the ephemeral resource manager
-	diags = diags.Append(ctx.EphemeralResources().Close(context.TODO()))
+	diags = diags.Append(ctx.EphemeralResources().Close(ctx.StopCtx()))
 
 	switch op {
 	case walkApply, walkDestroy:

internal/terraform/node_resource_ephemeral.go

@@ -124,12 +124,8 @@ func ephemeralResourceOpen(ctx EvalContext, inp ephemeralResourceInput) tfdiags.
 		provider: provider,
 		internal: resp.InternalContext,
 	}
-	// TODO: What can we use as a signal to cancel the context we're passing in
-	// here, so that the object will stop renewing things when we start shutting
-	// down?
-	// TODO: The context Stopped channel should probably be updated
-	// finally to a Context
-	ephemerals.RegisterInstance(context.TODO(), inp.addr, ephemeral.ResourceInstanceRegistration{
+
+	ephemerals.RegisterInstance(ctx.StopCtx(), inp.addr, ephemeral.ResourceInstanceRegistration{
 		Value:        resultVal,
 		ConfigBody:   config.Config,
 		Impl:         impl,
@@ -172,7 +168,7 @@ func (n *nodeEphemeralResourceClose) ModulePath() addrs.Module {
 func (n *nodeEphemeralResourceClose) Execute(ctx EvalContext, op walkOperation) tfdiags.Diagnostics {
 	log.Printf("[TRACE] nodeEphemeralResourceClose: closing all instances of %s", n.addr)
 	resources := ctx.EphemeralResources()
-	return resources.CloseInstances(context.TODO(), n.addr)
+	return resources.CloseInstances(ctx.StopCtx(), n.addr)
 }
 
 // ephemeralResourceInstImpl implements ephemeral.ResourceInstance as an