terraform/terraform/transform_provider.go

package terraform

import (
	"fmt"
	"log"
	"strings"

	"github.com/hashicorp/go-multierror"
	"github.com/hashicorp/terraform/dag"
)

// GraphNodeProvider is an interface that nodes that can be a provider
// must implement.
// ProviderName returns the name of the provider this satisfies.
// Name returns the full name of the provider in the config.
type GraphNodeProvider interface {
	ProviderName() string
	Name() string
}

// GraphNodeCloseProvider is an interface that nodes that can be a close
// provider must implement. The CloseProviderName returned is the name of
// the provider they satisfy.
type GraphNodeCloseProvider interface {
	CloseProviderName() string
}

// GraphNodeProviderConsumer is an interface that nodes that require
// a provider must implement. ProvidedBy must return the name of the provider
// to use.
type GraphNodeProviderConsumer interface {
	// TODO: make this return s string instead of a []string
	ProvidedBy() []string
	// Set the resolved provider address for this resource.
	SetProvider(string)
}

// ProviderTransformer is a GraphTransformer that maps resources to
// providers within the graph. This will error if there are any resources
// that don't map to proper resources.
type ProviderTransformer struct{}

func (t *ProviderTransformer) Transform(g *Graph) error {
	// Go through the other nodes and match them to providers they need
	var err error
	m := providerVertexMap(g)
	for _, v := range g.Vertices() {
		if pv, ok := v.(GraphNodeProviderConsumer); ok {
			p := pv.ProvidedBy()[0]

			key := providerMapKey(p, pv)
			target := m[key]

			sp, ok := pv.(GraphNodeSubPath)
			if !ok && target == nil {
				// no target, and no path to walk up
				err = multierror.Append(err, fmt.Errorf(
					"%s: provider %s couldn't be found",
					dag.VertexName(v), p))
				break
			}

			// if we don't have a provider at this level, walk up the path looking for one
			for i := 1; target == nil; i++ {
				path := normalizeModulePath(sp.Path())
				if len(path) < i {
					break
				}

				key = ResolveProviderName(p, path[:len(path)-i])
				target = m[key]
				if target != nil {
					break
				}
			}

			if target == nil {
				err = multierror.Append(err, fmt.Errorf(
					"%s: provider %s couldn't be found",
					dag.VertexName(v), p))
				break
			}

			pv.SetProvider(key)
			g.Connect(dag.BasicEdge(v, target))
		}
	}

	return err
}

// CloseProviderTransformer is a GraphTransformer that adds nodes to the
// graph that will close open provider connections that aren't needed anymore.
// A provider connection is not needed anymore once all depended resources
// in the graph are evaluated.
type CloseProviderTransformer struct{}

func (t *CloseProviderTransformer) Transform(g *Graph) error {
	pm := providerVertexMap(g)
	cpm := make(map[string]*graphNodeCloseProvider)
	var err error

	for _, v := range pm {
		p := v.(GraphNodeProvider)

		// get the close provider of this type if we alread created it
		closer := cpm[p.ProviderName()]

		if closer == nil {
			// create a closer for this provider type
			closer = &graphNodeCloseProvider{ProviderNameValue: p.ProviderName()}
			g.Add(closer)
			cpm[p.ProviderName()] = closer
		}

		// Close node depends on the provider itself
		// this is added unconditionally, so it will connect to all instances
		// of the provider. Extra edges will be removed by transitive
		// reduction.
		g.Connect(dag.BasicEdge(closer, p))

		// connect all the provider's resources to the close node
		for _, s := range g.UpEdges(p).List() {
			if _, ok := s.(GraphNodeResource); ok {
				g.Connect(dag.BasicEdge(closer, s))
			}
		}
	}

	return err
}

// MissingProviderTransformer is a GraphTransformer that adds nodes for all
// required providers into the graph. Specifically, it creates provider
// configuration nodes for all the providers that we support. These are pruned
// later during an optimization pass.
type MissingProviderTransformer struct {
	// Providers is the list of providers we support.
	Providers []string

	// AllowAny will not check that a provider is supported before adding
	// it to the graph.
	AllowAny bool

	// Concrete, if set, overrides how the providers are made.
	Concrete ConcreteProviderNodeFunc
}

func (t *MissingProviderTransformer) Transform(g *Graph) error {
	// Initialize factory
	if t.Concrete == nil {
		t.Concrete = func(a *NodeAbstractProvider) dag.Vertex {
			return a
		}
	}

	// Create a set of our supported providers
	supported := make(map[string]struct{}, len(t.Providers))
	for _, v := range t.Providers {
		supported[v] = struct{}{}
	}

	// Get the map of providers we already have in our graph
	m := providerVertexMap(g)

	// Go through all the provider consumers and make sure we add
	// that provider if it is missing. We use a for loop here instead
	// of "range" since we'll modify check as we go to add more to check.
	check := g.Vertices()
	for i := 0; i < len(check); i++ {
		v := check[i]

		pv, ok := v.(GraphNodeProviderConsumer)
		if !ok {
			continue
		}

		// If this node has a subpath, then we use that as a prefix
		// into our map to check for an existing provider.
		var path []string
		if sp, ok := pv.(GraphNodeSubPath); ok {
			raw := normalizeModulePath(sp.Path())
			if len(raw) > len(rootModulePath) {
				path = raw
			}
		}

		p := pv.ProvidedBy()[0]
		// always add the parent nodes to check, since configured providers
		// may have already been added for modules.
		if len(path) > 0 {
			// We'll need the parent provider as well, so let's
			// add a dummy node to check to make sure that we add
			// that parent provider.
			check = append(check, &graphNodeProviderConsumerDummy{
				ProviderValue: p,
				PathValue:     path[:len(path)-1],
			})
		}

		key := providerMapKey(p, pv)
		if _, ok := m[key]; ok {
			// This provider already exists as a configure node
			continue
		}

		// If the provider has an alias in it, we just want the type
		// TODO: jbardin -- stop adding aliased providers altogether
		ptype := p
		if idx := strings.IndexRune(p, '.'); idx != -1 {
			ptype = p[:idx]
		}

		if !t.AllowAny {
			if _, ok := supported[ptype]; !ok {
				// If we don't support the provider type, skip it.
				// Validation later will catch this as an error.
				continue
			}
		}

		// Add the missing provider node to the graph
		provider := t.Concrete(&NodeAbstractProvider{
			NameValue: p,
			PathValue: path,
		}).(dag.Vertex)

		m[key] = g.Add(provider)
	}

	return nil
}

// ParentProviderTransformer connects provider nodes to their parents.
//
// This works by finding nodes that are both GraphNodeProviders and
// GraphNodeSubPath. It then connects the providers to their parent
// path.
type ParentProviderTransformer struct{}

func (t *ParentProviderTransformer) Transform(g *Graph) error {
	// Make a mapping of path to dag.Vertex, where path is: "path.name"
	m := make(map[string]dag.Vertex)

	// Also create a map that maps a provider to its parent
	parentMap := make(map[dag.Vertex]string)
	for _, raw := range g.Vertices() {
		// If it is the flat version, then make it the non-flat version.
		// We eventually want to get rid of the flat version entirely so
		// this is a stop-gap while it still exists.
		var v dag.Vertex = raw

		// Only care about providers
		pn, ok := v.(GraphNodeProvider)
		if !ok || pn.ProviderName() == "" {
			continue
		}

		// Also require a subpath, if there is no subpath then we
		// just totally ignore it. The expectation of this transform is
		// that it is used with a graph builder that is already flattened.
		var path []string
		if pn, ok := raw.(GraphNodeSubPath); ok {
			path = pn.Path()
		}
		path = normalizeModulePath(path)

		key := ResolveProviderName(pn.ProviderName(), path)
		m[key] = raw

		// Determine the parent if we're non-root. This is length 1 since
		// the 0 index should be "root" since we normalize above.
		if len(path) > 1 {
			path = path[:len(path)-1]
			key := ResolveProviderName(pn.ProviderName(), path)
			parentMap[raw] = key
		}
	}

	// Connect!
	for v, key := range parentMap {
		if parent, ok := m[key]; ok {
			g.Connect(dag.BasicEdge(v, parent))
		}
	}

	return nil
}

// PruneProviderTransformer is a GraphTransformer that prunes all the
// providers that aren't needed from the graph. A provider is unneeded if
// no resource or module is using that provider.
type PruneProviderTransformer struct{}

func (t *PruneProviderTransformer) Transform(g *Graph) error {
	for _, v := range g.Vertices() {
		// We only care about the providers
		if pn, ok := v.(GraphNodeProvider); !ok || pn.ProviderName() == "" {
			continue
		}
		// Does anything depend on this? If not, then prune it.
		if s := g.UpEdges(v); s.Len() == 0 {
			if nv, ok := v.(dag.NamedVertex); ok {
				log.Printf("[DEBUG] Pruning provider with no dependencies: %s", nv.Name())
			}
			g.Remove(v)
		}
	}

	return nil
}

// providerMapKey is a helper that gives us the key to use for the
// maps returned by things such as providerVertexMap.
func providerMapKey(k string, v dag.Vertex) string {
	// we create a dummy provider to
	var path []string
	if sp, ok := v.(GraphNodeSubPath); ok {
		path = normalizeModulePath(sp.Path())
	}
	return ResolveProviderName(k, path)
}

func providerVertexMap(g *Graph) map[string]dag.Vertex {
	m := make(map[string]dag.Vertex)
	for _, v := range g.Vertices() {
		if pv, ok := v.(GraphNodeProvider); ok {
			m[pv.Name()] = v
		}
	}

	return m
}

func closeProviderVertexMap(g *Graph) map[string]dag.Vertex {
	m := make(map[string]dag.Vertex)
	for _, v := range g.Vertices() {
		if pv, ok := v.(GraphNodeCloseProvider); ok {
			m[pv.CloseProviderName()] = v
		}
	}

	return m
}

type graphNodeCloseProvider struct {
	ProviderNameValue string
}

func (n *graphNodeCloseProvider) Name() string {
	return fmt.Sprintf("provider.%s (close)", n.ProviderNameValue)
}

// GraphNodeEvalable impl.
func (n *graphNodeCloseProvider) EvalTree() EvalNode {
	return CloseProviderEvalTree(n.ProviderNameValue)
}

// GraphNodeDependable impl.
func (n *graphNodeCloseProvider) DependableName() []string {
	return []string{n.Name()}
}

func (n *graphNodeCloseProvider) CloseProviderName() string {
	return n.ProviderNameValue
}

// GraphNodeDotter impl.
func (n *graphNodeCloseProvider) DotNode(name string, opts *dag.DotOpts) *dag.DotNode {
	if !opts.Verbose {
		return nil
	}
	return &dag.DotNode{
		Name: name,
		Attrs: map[string]string{
			"label": n.Name(),
			"shape": "diamond",
		},
	}
}

// RemovableIfNotTargeted
func (n *graphNodeCloseProvider) RemoveIfNotTargeted() bool {
	// We need to add this so that this node will be removed if
	// it isn't targeted or a dependency of a target.
	return true
}

// graphNodeProviderConsumerDummy is a struct that never enters the real
// graph (though it could to no ill effect). It implements
// GraphNodeProviderConsumer and GraphNodeSubpath as a way to force
// certain transformations.
type graphNodeProviderConsumerDummy struct {
	ProviderValue string
	PathValue     []string
}

func (n *graphNodeProviderConsumerDummy) Path() []string {
	return n.PathValue
}

func (n *graphNodeProviderConsumerDummy) ProvidedBy() []string {
	return []string{n.ProviderValue}
}

func (n *graphNodeProviderConsumerDummy) SetProvider(string) {}