core: fix deadlock when dependable node replaced with non-dependable one

In #2884, Terraform would hang on graphs with an orphaned resource
depended on an orphaned module.

This is because orphan module nodes (which are dependable) were getting
expanded (replaced) with GraphNodeBasicSubgraph nodes (which are _not_
dependable).

The old `graph.Replace()` code resulted in GraphNodeBasicSubgraph being
entered into the lookaside table, even though it is not dependable.

This resulted in an untraversable edge in the graph, so the graph would
hang and wait forever.

Now, we remove entries from the lookaside table when a dependable node
is being replaced with a non-dependable node. This means we lose an
edge, but we can move forward. It's ~probably~ never correct to be
replacing depenable nodes with non-dependable ones, but this tweak
seemed preferable to tossing a panic in there.
This commit is contained in:
Paul Hinze 2015-08-10 15:04:48 -05:00
parent 7a464b1156
commit 52c4bfbe98
6 changed files with 157 additions and 4 deletions

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@ -4,6 +4,7 @@ import (
"reflect" "reflect"
"sort" "sort"
"strings" "strings"
"sync"
"testing" "testing"
) )
@ -685,6 +686,100 @@ func TestContext2Refresh_vars(t *testing.T) {
} }
} }
func TestContext2Refresh_orphanModule(t *testing.T) {
p := testProvider("aws")
m := testModule(t, "refresh-module-orphan")
// Create a custom refresh function to track the order they were visited
var order []string
var orderLock sync.Mutex
p.RefreshFn = func(
info *InstanceInfo,
is *InstanceState) (*InstanceState, error) {
orderLock.Lock()
defer orderLock.Unlock()
order = append(order, is.ID)
return is, nil
}
state := &State{
Modules: []*ModuleState{
&ModuleState{
Path: rootModulePath,
Resources: map[string]*ResourceState{
"aws_instance.foo": &ResourceState{
Primary: &InstanceState{
ID: "i-abc123",
Attributes: map[string]string{
"childid": "i-bcd234",
"grandchildid": "i-cde345",
},
},
Dependencies: []string{
"module.child",
"module.child",
},
},
},
},
&ModuleState{
Path: append(rootModulePath, "child"),
Resources: map[string]*ResourceState{
"aws_instance.bar": &ResourceState{
Primary: &InstanceState{
ID: "i-bcd234",
Attributes: map[string]string{
"grandchildid": "i-cde345",
},
},
Dependencies: []string{
"module.grandchild",
},
},
},
Outputs: map[string]string{
"id": "i-bcd234",
"grandchild_id": "i-cde345",
},
},
&ModuleState{
Path: append(rootModulePath, "child", "grandchild"),
Resources: map[string]*ResourceState{
"aws_instance.baz": &ResourceState{
Primary: &InstanceState{
ID: "i-cde345",
},
},
},
Outputs: map[string]string{
"id": "i-cde345",
},
},
},
}
ctx := testContext2(t, &ContextOpts{
Module: m,
Providers: map[string]ResourceProviderFactory{
"aws": testProviderFuncFixed(p),
},
State: state,
})
testCheckDeadlock(t, func() {
_, err := ctx.Refresh()
if err != nil {
t.Fatalf("err: %s", err)
}
// TODO: handle order properly for orphaned modules / resources
// expected := []string{"i-abc123", "i-bcd234", "i-cde345"}
// if !reflect.DeepEqual(order, expected) {
// t.Fatalf("expected: %#v, got: %#v", expected, order)
// }
})
}
func TestContext2Validate(t *testing.T) { func TestContext2Validate(t *testing.T) {
p := testProvider("aws") p := testProvider("aws")
m := testModule(t, "validate-good") m := testModule(t, "validate-good")

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@ -74,7 +74,11 @@ func (g *Graph) Replace(o, n dag.Vertex) bool {
// Go through and update our lookaside to point to the new vertex // Go through and update our lookaside to point to the new vertex
for k, v := range g.dependableMap { for k, v := range g.dependableMap {
if v == o { if v == o {
g.dependableMap[k] = n if _, ok := n.(GraphNodeDependable); ok {
g.dependableMap[k] = n
} else {
delete(g.dependableMap, k)
}
} }
} }

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@ -1,6 +1,7 @@
package terraform package terraform
import ( import (
"reflect"
"strings" "strings"
"testing" "testing"
) )
@ -20,7 +21,7 @@ func TestGraphAdd(t *testing.T) {
func TestGraphConnectDependent(t *testing.T) { func TestGraphConnectDependent(t *testing.T) {
var g Graph var g Graph
g.Add(&testGraphDependable{VertexName: "a", Mock: []string{"a"}}) g.Add(&testGraphDependable{VertexName: "a"})
b := g.Add(&testGraphDependable{ b := g.Add(&testGraphDependable{
VertexName: "b", VertexName: "b",
DependentOnMock: []string{"a"}, DependentOnMock: []string{"a"},
@ -37,10 +38,40 @@ func TestGraphConnectDependent(t *testing.T) {
} }
} }
func TestGraphReplace_DependableWithNonDependable(t *testing.T) {
var g Graph
a := g.Add(&testGraphDependable{VertexName: "a"})
b := g.Add(&testGraphDependable{
VertexName: "b",
DependentOnMock: []string{"a"},
})
newA := "non-dependable-a"
if missing := g.ConnectDependent(b); len(missing) > 0 {
t.Fatalf("bad: %#v", missing)
}
if !g.Replace(a, newA) {
t.Fatalf("failed to replace")
}
c := g.Add(&testGraphDependable{
VertexName: "c",
DependentOnMock: []string{"a"},
})
// This should fail by reporting missing, since a node with dependable
// name "a" is no longer in the graph.
missing := g.ConnectDependent(c)
expected := []string{"a"}
if !reflect.DeepEqual(expected, missing) {
t.Fatalf("expected: %#v, got: %#v", expected, missing)
}
}
type testGraphDependable struct { type testGraphDependable struct {
VertexName string VertexName string
DependentOnMock []string DependentOnMock []string
Mock []string
} }
func (v *testGraphDependable) Name() string { func (v *testGraphDependable) Name() string {
@ -48,7 +79,7 @@ func (v *testGraphDependable) Name() string {
} }
func (v *testGraphDependable) DependableName() []string { func (v *testGraphDependable) DependableName() []string {
return v.Mock return []string{v.VertexName}
} }
func (v *testGraphDependable) DependentOn() []string { func (v *testGraphDependable) DependentOn() []string {

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@ -0,0 +1,3 @@
resource "aws_instance" "baz" {}
output "id" { value = "${aws_instance.baz.id}" }

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@ -0,0 +1,10 @@
module "grandchild" {
source = "./grandchild"
}
resource "aws_instance" "bar" {
grandchildid = "${module.grandchild.id}"
}
output "id" { value = "${aws_instance.bar.id}" }
output "grandchild_id" { value = "${module.grandchild.id}" }

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@ -0,0 +1,10 @@
/*
module "child" {
source = "./child"
}
resource "aws_instance" "bar" {
childid = "${module.child.id}"
grandchildid = "${module.child.grandchild_id}"
}
*/