Merge pull request #30151 from hashicorp/f-non-existing-module-instance-crash

core: Fix crash with orphaned module instance
This commit is contained in:
Alisdair McDiarmid 2021-12-14 09:10:41 -05:00 committed by GitHub
commit aa59eb427a
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5 changed files with 251 additions and 8 deletions

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@ -107,6 +107,11 @@ func ResourceChange(
case plans.ResourceInstanceDeleteBecauseNoResourceConfig:
buf.WriteString(fmt.Sprintf("\n # (because %s is not in configuration)", addr.Resource.Resource))
case plans.ResourceInstanceDeleteBecauseNoModule:
// FIXME: Ideally we'd truncate addr.Module to reflect the earliest
// step that doesn't exist, so it's clearer which call this refers
// to, but we don't have enough information out here in the UI layer
// to decide that; only the "expander" in Terraform Core knows
// which module instance keys are actually declared.
buf.WriteString(fmt.Sprintf("\n # (because %s is not in configuration)", addr.Module))
case plans.ResourceInstanceDeleteBecauseWrongRepetition:
// We have some different variations of this one

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@ -120,6 +120,41 @@ func (e *Expander) ExpandModule(addr addrs.Module) []addrs.ModuleInstance {
return ret
}
// GetDeepestExistingModuleInstance is a funny specialized function for
// determining how many steps we can traverse through the given module instance
// address before encountering an undeclared instance of a declared module.
//
// The result is the longest prefix of the given address which steps only
// through module instances that exist.
//
// All of the modules on the given path must already have had their
// expansion registered using one of the SetModule* methods before calling,
// or this method will panic.
func (e *Expander) GetDeepestExistingModuleInstance(given addrs.ModuleInstance) addrs.ModuleInstance {
exps := e.exps // start with the root module expansions
for i := 0; i < len(given); i++ {
step := given[i]
callName := step.Name
if _, ok := exps.moduleCalls[addrs.ModuleCall{Name: callName}]; !ok {
// This is a bug in the caller, because it should always register
// expansions for an object and all of its ancestors before requesting
// expansion of it.
panic(fmt.Sprintf("no expansion has been registered for %s", given[:i].Child(callName, addrs.NoKey)))
}
var ok bool
exps, ok = exps.childInstances[step]
if !ok {
// We've found a non-existing instance, so we're done.
return given[:i]
}
}
// If we complete the loop above without returning early then the entire
// given address refers to a declared module instance.
return given
}
// ExpandModuleResource finds the exhaustive set of resource instances resulting from
// the expansion of the given resource and all of its containing modules.
//
@ -149,6 +184,14 @@ func (e *Expander) ExpandModuleResource(moduleAddr addrs.Module, resourceAddr ad
// All of the modules on the path to the identified resource and the resource
// itself must already have had their expansion registered using one of the
// SetModule*/SetResource* methods before calling, or this method will panic.
//
// ExpandModuleResource returns all instances of a resource across all
// instances of its containing module, whereas this ExpandResource function
// is more specific and only expands within a single module instance. If
// any of the module instances selected in the module path of the given address
// aren't valid for that module's expansion then ExpandResource returns an
// empty result, reflecting that a non-existing module instance can never
// contain any existing resource instances.
func (e *Expander) ExpandResource(resourceAddr addrs.AbsResource) []addrs.AbsResourceInstance {
e.mu.RLock()
defer e.mu.RUnlock()
@ -380,9 +423,23 @@ func (m *expanderModule) resourceInstances(moduleAddr addrs.ModuleInstance, reso
panic(fmt.Sprintf("no expansion has been registered for %s", parentAddr.Child(callName, addrs.NoKey)))
}
inst := m.childInstances[step]
moduleInstAddr := append(parentAddr, step)
return inst.resourceInstances(moduleAddr[1:], resourceAddr, moduleInstAddr)
if inst, ok := m.childInstances[step]; ok {
moduleInstAddr := append(parentAddr, step)
return inst.resourceInstances(moduleAddr[1:], resourceAddr, moduleInstAddr)
} else {
// If we have the module _call_ registered (as we checked above)
// but we don't have the given module _instance_ registered, that
// suggests that the module instance key in "step" is not declared
// by the current definition of this module call. That means the
// module instance doesn't exist at all, and therefore it can't
// possibly declare any resource instances either.
//
// For example, if we were asked about module.foo[0].aws_instance.bar
// but module.foo doesn't currently have count set, then there is no
// module.foo[0] at all, and therefore no aws_instance.bar
// instances inside it.
return nil
}
}
return m.onlyResourceInstances(resourceAddr, parentAddr)
}

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@ -199,14 +199,47 @@ func TestExpander(t *testing.T) {
}
})
t.Run("module single resource count2", func(t *testing.T) {
got := ex.ExpandModuleResource(
// Two different ways of asking the same question, which should
// both produce the same result.
// First: nested expansion of all instances of the resource across
// all instances of the module, but it's a single-instance module
// so the first level is a singleton.
got1 := ex.ExpandModuleResource(
mustModuleAddr(`single`),
count2ResourceAddr,
)
// Second: expansion of only instances belonging to a specific
// instance of the module, but again it's a single-instance module
// so there's only one to ask about.
got2 := ex.ExpandResource(
count2ResourceAddr.Absolute(
addrs.RootModuleInstance.Child("single", addrs.NoKey),
),
)
want := []addrs.AbsResourceInstance{
mustAbsResourceInstanceAddr(`module.single.test.count2[0]`),
mustAbsResourceInstanceAddr(`module.single.test.count2[1]`),
}
if diff := cmp.Diff(want, got1); diff != "" {
t.Errorf("wrong ExpandModuleResource result\n%s", diff)
}
if diff := cmp.Diff(want, got2); diff != "" {
t.Errorf("wrong ExpandResource result\n%s", diff)
}
})
t.Run("module single resource count2 with non-existing module instance", func(t *testing.T) {
got := ex.ExpandResource(
count2ResourceAddr.Absolute(
// Note: This is intentionally an invalid instance key,
// so we're asking about module.single[1].test.count2
// even though module.single doesn't have count set and
// therefore there is no module.single[1].
addrs.RootModuleInstance.Child("single", addrs.IntKey(1)),
),
)
// If the containing module instance doesn't exist then it can't
// possibly have any resource instances inside it.
want := ([]addrs.AbsResourceInstance)(nil)
if diff := cmp.Diff(want, got); diff != "" {
t.Errorf("wrong result\n%s", diff)
}
@ -261,6 +294,36 @@ func TestExpander(t *testing.T) {
t.Errorf("wrong result\n%s", diff)
}
})
t.Run("module count2 module count2 GetDeepestExistingModuleInstance", func(t *testing.T) {
t.Run("first step invalid", func(t *testing.T) {
got := ex.GetDeepestExistingModuleInstance(mustModuleInstanceAddr(`module.count2["nope"].module.count2[0]`))
want := addrs.RootModuleInstance
if !want.Equal(got) {
t.Errorf("wrong result\ngot: %s\nwant: %s", got, want)
}
})
t.Run("second step invalid", func(t *testing.T) {
got := ex.GetDeepestExistingModuleInstance(mustModuleInstanceAddr(`module.count2[1].module.count2`))
want := mustModuleInstanceAddr(`module.count2[1]`)
if !want.Equal(got) {
t.Errorf("wrong result\ngot: %s\nwant: %s", got, want)
}
})
t.Run("neither step valid", func(t *testing.T) {
got := ex.GetDeepestExistingModuleInstance(mustModuleInstanceAddr(`module.count2.module.count2["nope"]`))
want := addrs.RootModuleInstance
if !want.Equal(got) {
t.Errorf("wrong result\ngot: %s\nwant: %s", got, want)
}
})
t.Run("both steps valid", func(t *testing.T) {
got := ex.GetDeepestExistingModuleInstance(mustModuleInstanceAddr(`module.count2[1].module.count2[0]`))
want := mustModuleInstanceAddr(`module.count2[1].module.count2[0]`)
if !want.Equal(got) {
t.Errorf("wrong result\ngot: %s\nwant: %s", got, want)
}
})
})
t.Run("module count2 resource count2 resource count2", func(t *testing.T) {
got := ex.ExpandModuleResource(
mustModuleAddr(`count2.count2`),

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@ -2076,3 +2076,105 @@ output "output" {
}
}
}
func TestContext2Plan_moduleExpandOrphansResourceInstance(t *testing.T) {
// This test deals with the situation where a user has changed the
// repetition/expansion mode for a module call while there are already
// resource instances from the previous declaration in the state.
//
// This is conceptually just the same as removing the resources
// from the module configuration only for that instance, but the
// implementation of it ends up a little different because it's
// an entry in the resource address's _module path_ that we'll find
// missing, rather than the resource's own instance key, and so
// our analyses need to handle that situation by indicating that all
// of the resources under the missing module instance have zero
// instances, regardless of which resource in that module we might
// be asking about, and do so without tripping over any missing
// registrations in the instance expander that might lead to panics
// if we aren't careful.
//
// (For some history here, see https://github.com/hashicorp/terraform/issues/30110 )
addrNoKey := mustResourceInstanceAddr("module.child.test_object.a[0]")
addrZeroKey := mustResourceInstanceAddr("module.child[0].test_object.a[0]")
m := testModuleInline(t, map[string]string{
"main.tf": `
module "child" {
source = "./child"
count = 1
}
`,
"child/main.tf": `
resource "test_object" "a" {
count = 1
}
`,
})
state := states.BuildState(func(s *states.SyncState) {
// Notice that addrNoKey is the address which lacks any instance key
// for module.child, and so that module instance doesn't match the
// call declared above with count = 1, and therefore the resource
// inside is "orphaned" even though the resource block actually
// still exists there.
s.SetResourceInstanceCurrent(addrNoKey, &states.ResourceInstanceObjectSrc{
AttrsJSON: []byte(`{}`),
Status: states.ObjectReady,
}, mustProviderConfig(`provider["registry.terraform.io/hashicorp/test"]`))
})
p := simpleMockProvider()
ctx := testContext2(t, &ContextOpts{
Providers: map[addrs.Provider]providers.Factory{
addrs.NewDefaultProvider("test"): testProviderFuncFixed(p),
},
})
plan, diags := ctx.Plan(m, state, &PlanOpts{
Mode: plans.NormalMode,
})
if diags.HasErrors() {
t.Fatalf("unexpected errors\n%s", diags.Err().Error())
}
t.Run(addrNoKey.String(), func(t *testing.T) {
instPlan := plan.Changes.ResourceInstance(addrNoKey)
if instPlan == nil {
t.Fatalf("no plan for %s at all", addrNoKey)
}
if got, want := instPlan.Addr, addrNoKey; !got.Equal(want) {
t.Errorf("wrong current address\ngot: %s\nwant: %s", got, want)
}
if got, want := instPlan.PrevRunAddr, addrNoKey; !got.Equal(want) {
t.Errorf("wrong previous run address\ngot: %s\nwant: %s", got, want)
}
if got, want := instPlan.Action, plans.Delete; got != want {
t.Errorf("wrong planned action\ngot: %s\nwant: %s", got, want)
}
if got, want := instPlan.ActionReason, plans.ResourceInstanceDeleteBecauseNoModule; got != want {
t.Errorf("wrong action reason\ngot: %s\nwant: %s", got, want)
}
})
t.Run(addrZeroKey.String(), func(t *testing.T) {
instPlan := plan.Changes.ResourceInstance(addrZeroKey)
if instPlan == nil {
t.Fatalf("no plan for %s at all", addrZeroKey)
}
if got, want := instPlan.Addr, addrZeroKey; !got.Equal(want) {
t.Errorf("wrong current address\ngot: %s\nwant: %s", got, want)
}
if got, want := instPlan.PrevRunAddr, addrZeroKey; !got.Equal(want) {
t.Errorf("wrong previous run address\ngot: %s\nwant: %s", got, want)
}
if got, want := instPlan.Action, plans.Create; got != want {
t.Errorf("wrong planned action\ngot: %s\nwant: %s", got, want)
}
if got, want := instPlan.ActionReason, plans.ResourceInstanceChangeNoReason; got != want {
t.Errorf("wrong action reason\ngot: %s\nwant: %s", got, want)
}
})
}

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@ -157,13 +157,29 @@ func (n *NodePlannableResourceInstanceOrphan) managedResourceExecute(ctx EvalCon
func (n *NodePlannableResourceInstanceOrphan) deleteActionReason(ctx EvalContext) plans.ResourceInstanceChangeActionReason {
cfg := n.Config
if cfg == nil {
// NOTE: We'd ideally detect if the containing module is what's missing
// and then use ResourceInstanceDeleteBecauseNoModule for that case,
// but we don't currently have access to the full configuration here,
// so we need to be less specific.
return plans.ResourceInstanceDeleteBecauseNoResourceConfig
}
// If this is a resource instance inside a module instance that's no
// longer declared then we will have a config (because config isn't
// instance-specific) but the expander will know that our resource
// address's module path refers to an undeclared module instance.
if expander := ctx.InstanceExpander(); expander != nil { // (sometimes nil in MockEvalContext in tests)
validModuleAddr := expander.GetDeepestExistingModuleInstance(n.Addr.Module)
if len(validModuleAddr) != len(n.Addr.Module) {
// If we get here then at least one step in the resource's module
// path is to a module instance that doesn't exist at all, and
// so a missing module instance is the delete reason regardless
// of whether there might _also_ be a change to the resource
// configuration inside the module. (Conceptually the configurations
// inside the non-existing module instance don't exist at all,
// but they end up existing just as an artifact of the
// implementation detail that we detect module instance orphans
// only dynamically.)
return plans.ResourceInstanceDeleteBecauseNoModule
}
}
switch n.Addr.Resource.Key.(type) {
case nil: // no instance key at all
if cfg.Count != nil || cfg.ForEach != nil {