Initial transfer of provider code

10 files changed, 883 insertions, 0 deletions

diff --git a/vendor/github.com/hashicorp/terraform/config/module/copy_dir.go b/vendor/github.com/hashicorp/terraform/config/module/copy_dir.go
new file mode 100644
index 0000000..095f61d
--- /dev/null
+++ b/vendor/github.com/hashicorp/terraform/config/module/copy_dir.go
@@ -0,0 +1,114 @@
+package module
+
+import (
+        "io"
+        "os"
+        "path/filepath"
+        "strings"
+)
+
+// copyDir copies the src directory contents into dst. Both directories
+// should already exist.
+func copyDir(dst, src string) error {
+        src, err := filepath.EvalSymlinks(src)
+        if err != nil {
+                return err
+        }
+
+        walkFn := func(path string, info os.FileInfo, err error) error {
+                if err != nil {
+                        return err
+                }
+
+                if path == src {
+                        return nil
+                }
+
+                if strings.HasPrefix(filepath.Base(path), ".") {
+                        // Skip any dot files
+                        if info.IsDir() {
+                                return filepath.SkipDir
+                        } else {
+                                return nil
+                        }
+                }
+
+                // The "path" has the src prefixed to it. We need to join our
+                // destination with the path without the src on it.
+                dstPath := filepath.Join(dst, path[len(src):])
+
+                // we don't want to try and copy the same file over itself.
+                if eq, err := sameFile(path, dstPath); eq {
+                        return nil
+                } else if err != nil {
+                        return err
+                }
+
+                // If we have a directory, make that subdirectory, then continue
+                // the walk.
+                if info.IsDir() {
+                        if path == filepath.Join(src, dst) {
+                                // dst is in src; don't walk it.
+                                return nil
+                        }
+
+                        if err := os.MkdirAll(dstPath, 0755); err != nil {
+                                return err
+                        }
+
+                        return nil
+                }
+
+                // If we have a file, copy the contents.
+                srcF, err := os.Open(path)
+                if err != nil {
+                        return err
+                }
+                defer srcF.Close()
+
+                dstF, err := os.Create(dstPath)
+                if err != nil {
+                        return err
+                }
+                defer dstF.Close()
+
+                if _, err := io.Copy(dstF, srcF); err != nil {
+                        return err
+                }
+
+                // Chmod it
+                return os.Chmod(dstPath, info.Mode())
+        }
+
+        return filepath.Walk(src, walkFn)
+}
+
+// sameFile tried to determine if to paths are the same file.
+// If the paths don't match, we lookup the inode on supported systems.
+func sameFile(a, b string) (bool, error) {
+        if a == b {
+                return true, nil
+        }
+
+        aIno, err := inode(a)
+        if err != nil {
+                if os.IsNotExist(err) {
+                        return false, nil
+                }
+                return false, err
+        }
+
+        bIno, err := inode(b)
+        if err != nil {
+                if os.IsNotExist(err) {
+                        return false, nil
+                }
+                return false, err
+        }
+
+        if aIno > 0 && aIno == bIno {
+                return true, nil
+        }
+
+        return false, nil
+}
diff --git a/vendor/github.com/hashicorp/terraform/config/module/get.go b/vendor/github.com/hashicorp/terraform/config/module/get.go
new file mode 100644
index 0000000..96b4a63
--- /dev/null
+++ b/vendor/github.com/hashicorp/terraform/config/module/get.go
@@ -0,0 +1,71 @@
+package module
+
+import (
+        "io/ioutil"
+        "os"
+
+        "github.com/hashicorp/go-getter"
+)
+
+// GetMode is an enum that describes how modules are loaded.
+//
+// GetModeLoad says that modules will not be downloaded or updated, they will
+// only be loaded from the storage.
+//
+// GetModeGet says that modules can be initially downloaded if they don't
+// exist, but otherwise to just load from the current version in storage.
+//
+// GetModeUpdate says that modules should be checked for updates and
+// downloaded prior to loading. If there are no updates, we load the version
+// from disk, otherwise we download first and then load.
+type GetMode byte
+
+const (
+        GetModeNone GetMode = iota
+        GetModeGet
+        GetModeUpdate
+)
+
+// GetCopy is the same as Get except that it downloads a copy of the
+// module represented by source.
+//
+// This copy will omit and dot-prefixed files (such as .git/, .hg/) and
+// can't be updated on its own.
+func GetCopy(dst, src string) error {
+        // Create the temporary directory to do the real Get to
+        tmpDir, err := ioutil.TempDir("", "tf")
+        if err != nil {
+                return err
+        }
+        // FIXME: This isn't completely safe. Creating and removing our temp path
+        //        exposes where to race to inject files.
+        if err := os.RemoveAll(tmpDir); err != nil {
+                return err
+        }
+        defer os.RemoveAll(tmpDir)
+
+        // Get to that temporary dir
+        if err := getter.Get(tmpDir, src); err != nil {
+                return err
+        }
+
+        // Make sure the destination exists
+        if err := os.MkdirAll(dst, 0755); err != nil {
+                return err
+        }
+
+        // Copy to the final location
+        return copyDir(dst, tmpDir)
+}
+
+func getStorage(s getter.Storage, key string, src string, mode GetMode) (string, bool, error) {
+        // Get the module with the level specified if we were told to.
+        if mode > GetModeNone {
+                if err := s.Get(key, src, mode == GetModeUpdate); err != nil {
+                        return "", false, err
+                }
+        }
+
+        // Get the directory where the module is.
+        return s.Dir(key)
+}
diff --git a/vendor/github.com/hashicorp/terraform/config/module/inode.go b/vendor/github.com/hashicorp/terraform/config/module/inode.go
new file mode 100644
index 0000000..8603ee2
--- /dev/null
+++ b/vendor/github.com/hashicorp/terraform/config/module/inode.go
@@ -0,0 +1,21 @@
+// +build linux darwin openbsd netbsd solaris
+
+package module
+
+import (
+        "fmt"
+        "os"
+        "syscall"
+)
+
+// lookup the inode of a file on posix systems
+func inode(path string) (uint64, error) {
+        stat, err := os.Stat(path)
+        if err != nil {
+                return 0, err
+        }
+        if st, ok := stat.Sys().(*syscall.Stat_t); ok {
+                return st.Ino, nil
+        }
+        return 0, fmt.Errorf("could not determine file inode")
+}
diff --git a/vendor/github.com/hashicorp/terraform/config/module/inode_freebsd.go b/vendor/github.com/hashicorp/terraform/config/module/inode_freebsd.go
new file mode 100644
index 0000000..0d95730
--- /dev/null
+++ b/vendor/github.com/hashicorp/terraform/config/module/inode_freebsd.go
@@ -0,0 +1,21 @@
+// +build freebsd
+
+package module
+
+import (
+        "fmt"
+        "os"
+        "syscall"
+)
+
+// lookup the inode of a file on posix systems
+func inode(path string) (uint64, error) {
+        stat, err := os.Stat(path)
+        if err != nil {
+                return 0, err
+        }
+        if st, ok := stat.Sys().(*syscall.Stat_t); ok {
+                return uint64(st.Ino), nil
+        }
+        return 0, fmt.Errorf("could not determine file inode")
+}
diff --git a/vendor/github.com/hashicorp/terraform/config/module/inode_windows.go b/vendor/github.com/hashicorp/terraform/config/module/inode_windows.go
new file mode 100644
index 0000000..c0cf455
--- /dev/null
+++ b/vendor/github.com/hashicorp/terraform/config/module/inode_windows.go
@@ -0,0 +1,8 @@
+// +build windows
+
+package module
+
+// no syscall.Stat_t on windows, return 0 for inodes
+func inode(path string) (uint64, error) {
+        return 0, nil
+}
diff --git a/vendor/github.com/hashicorp/terraform/config/module/module.go b/vendor/github.com/hashicorp/terraform/config/module/module.go
new file mode 100644
index 0000000..f8649f6
--- /dev/null
+++ b/vendor/github.com/hashicorp/terraform/config/module/module.go
@@ -0,0 +1,7 @@
+package module
+
+// Module represents the metadata for a single module.
+type Module struct {
+        Name   string
+        Source string
+}
diff --git a/vendor/github.com/hashicorp/terraform/config/module/testing.go b/vendor/github.com/hashicorp/terraform/config/module/testing.go
new file mode 100644
index 0000000..fc9e733
--- /dev/null
+++ b/vendor/github.com/hashicorp/terraform/config/module/testing.go
@@ -0,0 +1,38 @@
+package module
+
+import (
+        "io/ioutil"
+        "os"
+        "testing"
+
+        "github.com/hashicorp/go-getter"
+)
+
+// TestTree loads a module at the given path and returns the tree as well
+// as a function that should be deferred to clean up resources.
+func TestTree(t *testing.T, path string) (*Tree, func()) {
+        // Create a temporary directory for module storage
+        dir, err := ioutil.TempDir("", "tf")
+        if err != nil {
+                t.Fatalf("err: %s", err)
+                return nil, nil
+        }
+
+        // Load the module
+        mod, err := NewTreeModule("", path)
+        if err != nil {
+                t.Fatalf("err: %s", err)
+                return nil, nil
+        }
+
+        // Get the child modules
+        s := &getter.FolderStorage{StorageDir: dir}
+        if err := mod.Load(s, GetModeGet); err != nil {
+                t.Fatalf("err: %s", err)
+                return nil, nil
+        }
+
+        return mod, func() {
+                os.RemoveAll(dir)
+        }
+}
diff --git a/vendor/github.com/hashicorp/terraform/config/module/tree.go b/vendor/github.com/hashicorp/terraform/config/module/tree.go
new file mode 100644
index 0000000..b6f90fd
--- /dev/null
+++ b/vendor/github.com/hashicorp/terraform/config/module/tree.go
@@ -0,0 +1,428 @@
+package module
+
+import (
+        "bufio"
+        "bytes"
+        "fmt"
+        "path/filepath"
+        "strings"
+        "sync"
+
+        "github.com/hashicorp/go-getter"
+        "github.com/hashicorp/terraform/config"
+)
+
+// RootName is the name of the root tree.
+const RootName = "root"
+
+// Tree represents the module import tree of configurations.
+//
+// This Tree structure can be used to get (download) new modules, load
+// all the modules without getting, flatten the tree into something
+// Terraform can use, etc.
+type Tree struct {
+        name     string
+        config   *config.Config
+        children map[string]*Tree
+        path     []string
+        lock     sync.RWMutex
+}
+
+// NewTree returns a new Tree for the given config structure.
+func NewTree(name string, c *config.Config) *Tree {
+        return &Tree{config: c, name: name}
+}
+
+// NewEmptyTree returns a new tree that is empty (contains no configuration).
+func NewEmptyTree() *Tree {
+        t := &Tree{config: &config.Config{}}
+
+        // We do this dummy load so that the tree is marked as "loaded". It
+        // should never fail because this is just about a no-op. If it does fail
+        // we panic so we can know its a bug.
+        if err := t.Load(nil, GetModeGet); err != nil {
+                panic(err)
+        }
+
+        return t
+}
+
+// NewTreeModule is like NewTree except it parses the configuration in
+// the directory and gives it a specific name. Use a blank name "" to specify
+// the root module.
+func NewTreeModule(name, dir string) (*Tree, error) {
+        c, err := config.LoadDir(dir)
+        if err != nil {
+                return nil, err
+        }
+
+        return NewTree(name, c), nil
+}
+
+// Config returns the configuration for this module.
+func (t *Tree) Config() *config.Config {
+        return t.config
+}
+
+// Child returns the child with the given path (by name).
+func (t *Tree) Child(path []string) *Tree {
+        if t == nil {
+                return nil
+        }
+
+        if len(path) == 0 {
+                return t
+        }
+
+        c := t.Children()[path[0]]
+        if c == nil {
+                return nil
+        }
+
+        return c.Child(path[1:])
+}
+
+// Children returns the children of this tree (the modules that are
+// imported by this root).
+//
+// This will only return a non-nil value after Load is called.
+func (t *Tree) Children() map[string]*Tree {
+        t.lock.RLock()
+        defer t.lock.RUnlock()
+        return t.children
+}
+
+// Loaded says whether or not this tree has been loaded or not yet.
+func (t *Tree) Loaded() bool {
+        t.lock.RLock()
+        defer t.lock.RUnlock()
+        return t.children != nil
+}
+
+// Modules returns the list of modules that this tree imports.
+//
+// This is only the imports of _this_ level of the tree. To retrieve the
+// full nested imports, you'll have to traverse the tree.
+func (t *Tree) Modules() []*Module {
+        result := make([]*Module, len(t.config.Modules))
+        for i, m := range t.config.Modules {
+                result[i] = &Module{
+                        Name:   m.Name,
+                        Source: m.Source,
+                }
+        }
+
+        return result
+}
+
+// Name returns the name of the tree. This will be "<root>" for the root
+// tree and then the module name given for any children.
+func (t *Tree) Name() string {
+        if t.name == "" {
+                return RootName
+        }
+
+        return t.name
+}
+
+// Load loads the configuration of the entire tree.
+//
+// The parameters are used to tell the tree where to find modules and
+// whether it can download/update modules along the way.
+//
+// Calling this multiple times will reload the tree.
+//
+// Various semantic-like checks are made along the way of loading since
+// module trees inherently require the configuration to be in a reasonably
+// sane state: no circular dependencies, proper module sources, etc. A full
+// suite of validations can be done by running Validate (after loading).
+func (t *Tree) Load(s getter.Storage, mode GetMode) error {
+        t.lock.Lock()
+        defer t.lock.Unlock()
+
+        // Reset the children if we have any
+        t.children = nil
+
+        modules := t.Modules()
+        children := make(map[string]*Tree)
+
+        // Go through all the modules and get the directory for them.
+        for _, m := range modules {
+                if _, ok := children[m.Name]; ok {
+                        return fmt.Errorf(
+                                "module %s: duplicated. module names must be unique", m.Name)
+                }
+
+                // Determine the path to this child
+                path := make([]string, len(t.path), len(t.path)+1)
+                copy(path, t.path)
+                path = append(path, m.Name)
+
+                // Split out the subdir if we have one
+                source, subDir := getter.SourceDirSubdir(m.Source)
+
+                source, err := getter.Detect(source, t.config.Dir, getter.Detectors)
+                if err != nil {
+                        return fmt.Errorf("module %s: %s", m.Name, err)
+                }
+
+                // Check if the detector introduced something new.
+                source, subDir2 := getter.SourceDirSubdir(source)
+                if subDir2 != "" {
+                        subDir = filepath.Join(subDir2, subDir)
+                }
+
+                // Get the directory where this module is so we can load it
+                key := strings.Join(path, ".")
+                key = fmt.Sprintf("root.%s-%s", key, m.Source)
+                dir, ok, err := getStorage(s, key, source, mode)
+                if err != nil {
+                        return err
+                }
+                if !ok {
+                        return fmt.Errorf(
+                                "module %s: not found, may need to be downloaded using 'terraform get'", m.Name)
+                }
+
+                // If we have a subdirectory, then merge that in
+                if subDir != "" {
+                        dir = filepath.Join(dir, subDir)
+                }
+
+                // Load the configurations.Dir(source)
+                children[m.Name], err = NewTreeModule(m.Name, dir)
+                if err != nil {
+                        return fmt.Errorf(
+                                "module %s: %s", m.Name, err)
+                }
+
+                // Set the path of this child
+                children[m.Name].path = path
+        }
+
+        // Go through all the children and load them.
+        for _, c := range children {
+                if err := c.Load(s, mode); err != nil {
+                        return err
+                }
+        }
+
+        // Set our tree up
+        t.children = children
+
+        return nil
+}
+
+// Path is the full path to this tree.
+func (t *Tree) Path() []string {
+        return t.path
+}
+
+// String gives a nice output to describe the tree.
+func (t *Tree) String() string {
+        var result bytes.Buffer
+        path := strings.Join(t.path, ", ")
+        if path != "" {
+                path = fmt.Sprintf(" (path: %s)", path)
+        }
+        result.WriteString(t.Name() + path + "\n")
+
+        cs := t.Children()
+        if cs == nil {
+                result.WriteString("  not loaded")
+        } else {
+                // Go through each child and get its string value, then indent it
+                // by two.
+                for _, c := range cs {
+                        r := strings.NewReader(c.String())
+                        scanner := bufio.NewScanner(r)
+                        for scanner.Scan() {
+                                result.WriteString("  ")
+                                result.WriteString(scanner.Text())
+                                result.WriteString("\n")
+                        }
+                }
+        }
+
+        return result.String()
+}
+
+// Validate does semantic checks on the entire tree of configurations.
+//
+// This will call the respective config.Config.Validate() functions as well
+// as verifying things such as parameters/outputs between the various modules.
+//
+// Load must be called prior to calling Validate or an error will be returned.
+func (t *Tree) Validate() error {
+        if !t.Loaded() {
+                return fmt.Errorf("tree must be loaded before calling Validate")
+        }
+
+        // If something goes wrong, here is our error template
+        newErr := &treeError{Name: []string{t.Name()}}
+
+        // Terraform core does not handle root module children named "root".
+        // We plan to fix this in the future but this bug was brought up in
+        // the middle of a release and we don't want to introduce wide-sweeping
+        // changes at that time.
+        if len(t.path) == 1 && t.name == "root" {
+                return fmt.Errorf("root module cannot contain module named 'root'")
+        }
+
+        // Validate our configuration first.
+        if err := t.config.Validate(); err != nil {
+                newErr.Add(err)
+        }
+
+        // If we're the root, we do extra validation. This validation usually
+        // requires the entire tree (since children don't have parent pointers).
+        if len(t.path) == 0 {
+                if err := t.validateProviderAlias(); err != nil {
+                        newErr.Add(err)
+                }
+        }
+
+        // Get the child trees
+        children := t.Children()
+
+        // Validate all our children
+        for _, c := range children {
+                err := c.Validate()
+                if err == nil {
+                        continue
+                }
+
+                verr, ok := err.(*treeError)
+                if !ok {
+                        // Unknown error, just return...
+                        return err
+                }
+
+                // Append ourselves to the error and then return
+                verr.Name = append(verr.Name, t.Name())
+                newErr.AddChild(verr)
+        }
+
+        // Go over all the modules and verify that any parameters are valid
+        // variables into the module in question.
+        for _, m := range t.config.Modules {
+                tree, ok := children[m.Name]
+                if !ok {
+                        // This should never happen because Load watches us
+                        panic("module not found in children: " + m.Name)
+                }
+
+                // Build the variables that the module defines
+                requiredMap := make(map[string]struct{})
+                varMap := make(map[string]struct{})
+                for _, v := range tree.config.Variables {
+                        varMap[v.Name] = struct{}{}
+
+                        if v.Required() {
+                                requiredMap[v.Name] = struct{}{}
+                        }
+                }
+
+                // Compare to the keys in our raw config for the module
+                for k, _ := range m.RawConfig.Raw {
+                        if _, ok := varMap[k]; !ok {
+                                newErr.Add(fmt.Errorf(
+                                        "module %s: %s is not a valid parameter",
+                                        m.Name, k))
+                        }
+
+                        // Remove the required
+                        delete(requiredMap, k)
+                }
+
+                // If we have any required left over, they aren't set.
+                for k, _ := range requiredMap {
+                        newErr.Add(fmt.Errorf(
+                                "module %s: required variable %q not set",
+                                m.Name, k))
+                }
+        }
+
+        // Go over all the variables used and make sure that any module
+        // variables represent outputs properly.
+        for source, vs := range t.config.InterpolatedVariables() {
+                for _, v := range vs {
+                        mv, ok := v.(*config.ModuleVariable)
+                        if !ok {
+                                continue
+                        }
+
+                        tree, ok := children[mv.Name]
+                        if !ok {
+                                newErr.Add(fmt.Errorf(
+                                        "%s: undefined module referenced %s",
+                                        source, mv.Name))
+                                continue
+                        }
+
+                        found := false
+                        for _, o := range tree.config.Outputs {
+                                if o.Name == mv.Field {
+                                        found = true
+                                        break
+                                }
+                        }
+                        if !found {
+                                newErr.Add(fmt.Errorf(
+                                        "%s: %s is not a valid output for module %s",
+                                        source, mv.Field, mv.Name))
+                        }
+                }
+        }
+
+        return newErr.ErrOrNil()
+}
+
+// treeError is an error use by Tree.Validate to accumulates all
+// validation errors.
+type treeError struct {
+        Name     []string
+        Errs     []error
+        Children []*treeError
+}
+
+func (e *treeError) Add(err error) {
+        e.Errs = append(e.Errs, err)
+}
+
+func (e *treeError) AddChild(err *treeError) {
+        e.Children = append(e.Children, err)
+}
+
+func (e *treeError) ErrOrNil() error {
+        if len(e.Errs) > 0 || len(e.Children) > 0 {
+                return e
+        }
+        return nil
+}
+
+func (e *treeError) Error() string {
+        name := strings.Join(e.Name, ".")
+        var out bytes.Buffer
+        fmt.Fprintf(&out, "module %s: ", name)
+
+        if len(e.Errs) == 1 {
+                // single like error
+                out.WriteString(e.Errs[0].Error())
+        } else {
+                // multi-line error
+                for _, err := range e.Errs {
+                        fmt.Fprintf(&out, "\n    %s", err)
+                }
+        }
+
+        if len(e.Children) > 0 {
+                // start the next error on a new line
+                out.WriteString("\n  ")
+        }
+        for _, child := range e.Children {
+                out.WriteString(child.Error())
+        }
+
+        return out.String()
+}
diff --git a/vendor/github.com/hashicorp/terraform/config/module/tree_gob.go b/vendor/github.com/hashicorp/terraform/config/module/tree_gob.go
new file mode 100644
index 0000000..fcd37f4
--- /dev/null
+++ b/vendor/github.com/hashicorp/terraform/config/module/tree_gob.go
@@ -0,0 +1,57 @@
+package module
+
+import (
+        "bytes"
+        "encoding/gob"
+
+        "github.com/hashicorp/terraform/config"
+)
+
+func (t *Tree) GobDecode(bs []byte) error {
+        t.lock.Lock()
+        defer t.lock.Unlock()
+
+        // Decode the gob data
+        var data treeGob
+        dec := gob.NewDecoder(bytes.NewReader(bs))
+        if err := dec.Decode(&data); err != nil {
+                return err
+        }
+
+        // Set the fields
+        t.name = data.Name
+        t.config = data.Config
+        t.children = data.Children
+        t.path = data.Path
+
+        return nil
+}
+
+func (t *Tree) GobEncode() ([]byte, error) {
+        data := &treeGob{
+                Config:   t.config,
+                Children: t.children,
+                Name:     t.name,
+                Path:     t.path,
+        }
+
+        var buf bytes.Buffer
+        enc := gob.NewEncoder(&buf)
+        if err := enc.Encode(data); err != nil {
+                return nil, err
+        }
+
+        return buf.Bytes(), nil
+}
+
+// treeGob is used as a structure to Gob encode a tree.
+//
+// This structure is private so it can't be referenced but the fields are
+// public, allowing Gob to properly encode this. When we decode this, we are
+// able to turn it into a Tree.
+type treeGob struct {
+        Config   *config.Config
+        Children map[string]*Tree
+        Name     string
+        Path     []string
+}
diff --git a/vendor/github.com/hashicorp/terraform/config/module/validate_provider_alias.go b/vendor/github.com/hashicorp/terraform/config/module/validate_provider_alias.go
new file mode 100644
index 0000000..090d4f7
--- /dev/null
+++ b/vendor/github.com/hashicorp/terraform/config/module/validate_provider_alias.go
@@ -0,0 +1,118 @@
+package module
+
+import (
+        "fmt"
+        "strings"
+
+        "github.com/hashicorp/go-multierror"
+        "github.com/hashicorp/terraform/dag"
+)
+
+// validateProviderAlias validates that all provider alias references are
+// defined at some point in the parent tree. This improves UX by catching
+// alias typos at the slight cost of requiring a declaration of usage. This
+// is usually a good tradeoff since not many aliases are used.
+func (t *Tree) validateProviderAlias() error {
+        // If we're not the root, don't perform this validation. We must be the
+        // root since we require full tree visibilty.
+        if len(t.path) != 0 {
+                return nil
+        }
+
+        // We'll use a graph to keep track of defined aliases at each level.
+        // As long as a parent defines an alias, it is okay.
+        var g dag.AcyclicGraph
+        t.buildProviderAliasGraph(&g, nil)
+
+        // Go through the graph and check that the usage is all good.
+        var err error
+        for _, v := range g.Vertices() {
+                pv, ok := v.(*providerAliasVertex)
+                if !ok {
+                        // This shouldn't happen, just ignore it.
+                        continue
+                }
+
+                // If we're not using any aliases, fast track and just continue
+                if len(pv.Used) == 0 {
+                        continue
+                }
+
+                // Grab the ancestors since we're going to have to check if our
+                // parents define any of our aliases.
+                var parents []*providerAliasVertex
+                ancestors, _ := g.Ancestors(v)
+                for _, raw := range ancestors.List() {
+                        if pv, ok := raw.(*providerAliasVertex); ok {
+                                parents = append(parents, pv)
+                        }
+                }
+                for k, _ := range pv.Used {
+                        // Check if we define this
+                        if _, ok := pv.Defined[k]; ok {
+                                continue
+                        }
+
+                        // Check for a parent
+                        found := false
+                        for _, parent := range parents {
+                                _, found = parent.Defined[k]
+                                if found {
+                                        break
+                                }
+                        }
+                        if found {
+                                continue
+                        }
+
+                        // We didn't find the alias, error!
+                        err = multierror.Append(err, fmt.Errorf(
+                                "module %s: provider alias must be defined by the module or a parent: %s",
+                                strings.Join(pv.Path, "."), k))
+                }
+        }
+
+        return err
+}
+
+func (t *Tree) buildProviderAliasGraph(g *dag.AcyclicGraph, parent dag.Vertex) {
+        // Add all our defined aliases
+        defined := make(map[string]struct{})
+        for _, p := range t.config.ProviderConfigs {
+                defined[p.FullName()] = struct{}{}
+        }
+
+        // Add all our used aliases
+        used := make(map[string]struct{})
+        for _, r := range t.config.Resources {
+                if r.Provider != "" {
+                        used[r.Provider] = struct{}{}
+                }
+        }
+
+        // Add it to the graph
+        vertex := &providerAliasVertex{
+                Path:    t.Path(),
+                Defined: defined,
+                Used:    used,
+        }
+        g.Add(vertex)
+
+        // Connect to our parent if we have one
+        if parent != nil {
+                g.Connect(dag.BasicEdge(vertex, parent))
+        }
+
+        // Build all our children
+        for _, c := range t.Children() {
+                c.buildProviderAliasGraph(g, vertex)
+        }
+}
+
+// providerAliasVertex is the vertex for the graph that keeps track of
+// defined provider aliases.
+type providerAliasVertex struct {
+        Path    []string
+        Defined map[string]struct{}
+        Used    map[string]struct{}
+}