terraform/terraform/transform_reference.go

496 lines
15 KiB
Go

package terraform
import (
"fmt"
"log"
"github.com/hashicorp/hcl2/hcl"
"github.com/hashicorp/terraform/configs/configschema"
"github.com/hashicorp/terraform/lang"
"github.com/hashicorp/terraform/addrs"
"github.com/hashicorp/terraform/config"
"github.com/hashicorp/terraform/dag"
)
// GraphNodeReferenceable must be implemented by any node that represents
// a Terraform thing that can be referenced (resource, module, etc.).
//
// Even if the thing has no name, this should return an empty list. By
// implementing this and returning a non-nil result, you say that this CAN
// be referenced and other methods of referencing may still be possible (such
// as by path!)
type GraphNodeReferenceable interface {
GraphNodeSubPath
// ReferenceableAddrs returns a list of addresses through which this can be
// referenced.
ReferenceableAddrs() []addrs.Referenceable
}
// GraphNodeReferencer must be implemented by nodes that reference other
// Terraform items and therefore depend on them.
type GraphNodeReferencer interface {
GraphNodeSubPath
// References returns a list of references made by this node, which
// include both a referenced address and source location information for
// the reference.
References() []*addrs.Reference
}
// GraphNodeReferenceOutside is an interface that can optionally be implemented.
// A node that implements it can specify that its own referenceable addresses
// and/or the addresses it references are in a different module than the
// node itself.
//
// Any referenceable addresses returned by ReferenceableAddrs are interpreted
// relative to the returned selfPath.
//
// Any references returned by References are interpreted relative to the
// returned referencePath.
//
// It is valid but not required for either of these paths to match what is
// returned by method Path, though if both match the main Path then there
// is no reason to implement this method.
//
// The primary use-case for this is the nodes representing module input
// variables, since their expressions are resolved in terms of their calling
// module, but they are still referenced from their own module.
type GraphNodeReferenceOutside interface {
// ReferenceOutside returns a path in which any references from this node
// are resolved.
ReferenceOutside() (selfPath, referencePath addrs.ModuleInstance)
}
// ReferenceTransformer is a GraphTransformer that connects all the
// nodes that reference each other in order to form the proper ordering.
type ReferenceTransformer struct{}
func (t *ReferenceTransformer) Transform(g *Graph) error {
// Build a reference map so we can efficiently look up the references
vs := g.Vertices()
m := NewReferenceMap(vs)
// Find the things that reference things and connect them
for _, v := range vs {
parents, _ := m.References(v)
parentsDbg := make([]string, len(parents))
for i, v := range parents {
parentsDbg[i] = dag.VertexName(v)
}
log.Printf(
"[DEBUG] ReferenceTransformer: %q references: %v",
dag.VertexName(v), parentsDbg)
for _, parent := range parents {
g.Connect(dag.BasicEdge(v, parent))
}
}
return nil
}
// DestroyReferenceTransformer is a GraphTransformer that reverses the edges
// for locals and outputs that depend on other nodes which will be
// removed during destroy. If a destroy node is evaluated before the local or
// output value, it will be removed from the state, and the later interpolation
// will fail.
type DestroyValueReferenceTransformer struct{}
func (t *DestroyValueReferenceTransformer) Transform(g *Graph) error {
vs := g.Vertices()
for _, v := range vs {
switch v.(type) {
case *NodeApplyableOutput, *NodeLocal:
// OK
default:
continue
}
// reverse any outgoing edges so that the value is evaluated first.
for _, e := range g.EdgesFrom(v) {
target := e.Target()
// only destroy nodes will be evaluated in reverse
if _, ok := target.(GraphNodeDestroyer); !ok {
continue
}
log.Printf("[TRACE] output dep: %s", dag.VertexName(target))
g.RemoveEdge(e)
g.Connect(&DestroyEdge{S: target, T: v})
}
}
return nil
}
// PruneUnusedValuesTransformer is s GraphTransformer that removes local and
// output values which are not referenced in the graph. Since outputs and
// locals always need to be evaluated, if they reference a resource that is not
// available in the state the interpolation could fail.
type PruneUnusedValuesTransformer struct{}
func (t *PruneUnusedValuesTransformer) Transform(g *Graph) error {
// this might need multiple runs in order to ensure that pruning a value
// doesn't effect a previously checked value.
for removed := 0; ; removed = 0 {
for _, v := range g.Vertices() {
switch v.(type) {
case *NodeApplyableOutput, *NodeLocal:
// OK
default:
continue
}
dependants := g.UpEdges(v)
switch dependants.Len() {
case 0:
// nothing at all depends on this
g.Remove(v)
removed++
case 1:
// because an output's destroy node always depends on the output,
// we need to check for the case of a single destroy node.
d := dependants.List()[0]
if _, ok := d.(*NodeDestroyableOutput); ok {
g.Remove(v)
removed++
}
}
}
if removed == 0 {
break
}
}
return nil
}
// ReferenceMap is a structure that can be used to efficiently check
// for references on a graph.
type ReferenceMap struct {
// vertices is a map from internal reference keys (as produced by the
// mapKey method) to one or more vertices that are identified by each key.
//
// A particular reference key might actually identify multiple vertices,
// e.g. in situations where one object is contained inside another.
vertices map[string][]dag.Vertex
// edges is a map whose keys are a subset of the internal reference keys
// from "vertices", and whose values are the nodes that refer to each
// key. The values in this map are the referrers, while values in
// "verticies" are the referents. The keys in both cases are referents.
edges map[string][]dag.Vertex
}
// References returns the set of vertices that the given vertex refers to,
// and any referenced addresses that do not have corresponding vertices.
func (m *ReferenceMap) References(v dag.Vertex) ([]dag.Vertex, []addrs.Referenceable) {
rn, ok := v.(GraphNodeReferencer)
if !ok {
return nil, nil
}
if _, ok := v.(GraphNodeSubPath); !ok {
return nil, nil
}
var matches []dag.Vertex
var missing []addrs.Referenceable
for _, ref := range rn.References() {
subject := ref.Subject
key := m.referenceMapKey(v, subject)
if _, exists := m.vertices[key]; !exists {
// If what we were looking for was a ResourceInstance then we
// might be in a resource-oriented graph rather than an
// instance-oriented graph, and so we'll see if we have the
// resource itself instead.
switch ri := subject.(type) {
case addrs.ResourceInstance:
subject = ri.ContainingResource()
case addrs.ResourceInstancePhase:
subject = ri.ContainingResource()
}
key = m.referenceMapKey(v, subject)
}
vertices := m.vertices[key]
for _, rv := range vertices {
// don't include self-references
if rv == v {
continue
}
matches = append(matches, rv)
}
if len(vertices) == 0 {
missing = append(missing, ref.Subject)
}
}
return matches, missing
}
// Referrers returns the set of vertices that refer to the given vertex.
func (m *ReferenceMap) Referrers(v dag.Vertex) []dag.Vertex {
rn, ok := v.(GraphNodeReferenceable)
if !ok {
return nil
}
sp, ok := v.(GraphNodeSubPath)
if !ok {
return nil
}
var matches []dag.Vertex
for _, addr := range rn.ReferenceableAddrs() {
key := m.mapKey(sp.Path(), addr)
referrers, ok := m.edges[key]
if !ok {
continue
}
// If the referrer set includes our own given vertex then we skip,
// since we don't want to return self-references.
selfRef := false
for _, p := range referrers {
if p == v {
selfRef = true
break
}
}
if selfRef {
continue
}
matches = append(matches, referrers...)
}
return matches
}
func (m *ReferenceMap) mapKey(path addrs.ModuleInstance, addr addrs.Referenceable) string {
return fmt.Sprintf("%s|%s", path.String(), addr.String())
}
// vertexReferenceablePath returns the path in which the given vertex can be
// referenced. This is the path that its results from ReferenceableAddrs
// are considered to be relative to.
//
// Only GraphNodeSubPath implementations can be referenced, so this method will
// panic if the given vertex does not implement that interface.
func (m *ReferenceMap) vertexReferenceablePath(v dag.Vertex) addrs.ModuleInstance {
sp, ok := v.(GraphNodeSubPath)
if !ok {
// Only nodes with paths can participate in a reference map.
panic(fmt.Errorf("vertexMapKey on vertex type %T which doesn't implement GraphNodeSubPath", sp))
}
if outside, ok := v.(GraphNodeReferenceOutside); ok {
// Vertex is referenced from a different module than where it was
// declared.
path, _ := outside.ReferenceOutside()
return path
}
// Vertex is referenced from the same module as where it was declared.
return sp.Path()
}
// vertexReferencePath returns the path in which references _from_ the given
// vertex must be interpreted.
//
// Only GraphNodeSubPath implementations can have references, so this method
// will panic if the given vertex does not implement that interface.
func vertexReferencePath(referrer dag.Vertex) addrs.ModuleInstance {
sp, ok := referrer.(GraphNodeSubPath)
if !ok {
// Only nodes with paths can participate in a reference map.
panic(fmt.Errorf("vertexReferencePath on vertex type %T which doesn't implement GraphNodeSubPath", sp))
}
var path addrs.ModuleInstance
if outside, ok := referrer.(GraphNodeReferenceOutside); ok {
// Vertex makes references to objects in a different module than where
// it was declared.
_, path = outside.ReferenceOutside()
return path
}
// Vertex makes references to objects in the same module as where it
// was declared.
return sp.Path()
}
// referenceMapKey produces keys for the "edges" map. "referrer" is the vertex
// that the reference is from, and "addr" is the address of the object being
// referenced.
//
// The result is an opaque string that includes both the address of the given
// object and the address of the module instance that object belongs to.
//
// Only GraphNodeSubPath implementations can be referrers, so this method will
// panic if the given vertex does not implement that interface.
func (m *ReferenceMap) referenceMapKey(referrer dag.Vertex, addr addrs.Referenceable) string {
path := vertexReferencePath(referrer)
return m.mapKey(path, addr)
}
// NewReferenceMap is used to create a new reference map for the
// given set of vertices.
func NewReferenceMap(vs []dag.Vertex) *ReferenceMap {
var m ReferenceMap
// Build the lookup table
vertices := make(map[string][]dag.Vertex)
for _, v := range vs {
_, ok := v.(GraphNodeSubPath)
if !ok {
// Only nodes with paths can participate in a reference map.
continue
}
// We're only looking for referenceable nodes
rn, ok := v.(GraphNodeReferenceable)
if !ok {
continue
}
path := m.vertexReferenceablePath(v)
// Go through and cache them
for _, addr := range rn.ReferenceableAddrs() {
key := m.mapKey(path, addr)
vertices[key] = append(vertices[key], v)
}
// Any node can be referenced by the address of the module it belongs
// to or any of that module's ancestors.
for _, addr := range path.Ancestors()[1:] {
// Can be referenced either as the specific call instance (with
// an instance key) or as the bare module call itself (the "module"
// block in the parent module that created the instance).
callPath, call := addr.Call()
callInstPath, callInst := addr.CallInstance()
callKey := m.mapKey(callPath, call)
callInstKey := m.mapKey(callInstPath, callInst)
vertices[callKey] = append(vertices[callKey], v)
vertices[callInstKey] = append(vertices[callInstKey], v)
}
}
// Build the lookup table for referenced by
edges := make(map[string][]dag.Vertex)
for _, v := range vs {
_, ok := v.(GraphNodeSubPath)
if !ok {
// Only nodes with paths can participate in a reference map.
continue
}
rn, ok := v.(GraphNodeReferencer)
if !ok {
// We're only looking for referenceable nodes
continue
}
// Go through and cache them
for _, ref := range rn.References() {
if ref.Subject == nil {
// Should never happen
panic(fmt.Sprintf("%T.References returned reference with nil subject", rn))
}
key := m.referenceMapKey(v, ref.Subject)
edges[key] = append(edges[key], v)
}
}
m.vertices = vertices
m.edges = edges
return &m
}
// ReferencesFromConfig returns the references that a configuration has
// based on the interpolated variables in a configuration.
func ReferencesFromConfig(body hcl.Body, schema *configschema.Block) []*addrs.Reference {
if body == nil {
return nil
}
refs, _ := lang.ReferencesInBlock(body, schema)
return refs
}
// ReferenceFromInterpolatedVar returns the reference from this variable,
// or an empty string if there is no reference.
func ReferenceFromInterpolatedVar(v config.InterpolatedVariable) []string {
switch v := v.(type) {
case *config.ModuleVariable:
return []string{fmt.Sprintf("module.%s.output.%s", v.Name, v.Field)}
case *config.ResourceVariable:
id := v.ResourceId()
// If we have a multi-reference (splat), then we depend on ALL
// resources with this type/name.
if v.Multi && v.Index == -1 {
return []string{fmt.Sprintf("%s.*", id)}
}
// Otherwise, we depend on a specific index.
idx := v.Index
if !v.Multi || v.Index == -1 {
idx = 0
}
// Depend on the index, as well as "N" which represents the
// un-expanded set of resources.
return []string{fmt.Sprintf("%s.%d/%s.N", id, idx, id)}
case *config.UserVariable:
return []string{fmt.Sprintf("var.%s", v.Name)}
case *config.LocalVariable:
return []string{fmt.Sprintf("local.%s", v.Name)}
default:
return nil
}
}
// appendResourceDestroyReferences identifies resource and resource instance
// references in the given slice and appends to it the "destroy-phase"
// equivalents of those references, returning the result.
//
// This can be used in the References implementation for a node which must also
// depend on the destruction of anything it references.
func appendResourceDestroyReferences(refs []*addrs.Reference) []*addrs.Reference {
given := refs
for _, ref := range given {
switch tr := ref.Subject.(type) {
case addrs.Resource:
newRef := *ref // shallow copy
newRef.Subject = tr.Phase(addrs.ResourceInstancePhaseDestroy)
refs = append(refs, &newRef)
case addrs.ResourceInstance:
newRef := *ref // shallow copy
newRef.Subject = tr.Phase(addrs.ResourceInstancePhaseDestroy)
refs = append(refs, &newRef)
}
}
return refs
}
func modulePrefixStr(p addrs.ModuleInstance) string {
return p.String()
}
func modulePrefixList(result []string, prefix string) []string {
if prefix != "" {
for i, v := range result {
result[i] = fmt.Sprintf("%s.%s", prefix, v)
}
}
return result
}