terraform/config/module/tree.go

292 lines
7.2 KiB
Go

package module
import (
"bufio"
"bytes"
"fmt"
"strings"
"sync"
"github.com/hashicorp/terraform/config"
)
// 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
lock sync.RWMutex
}
// 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
)
// NewTree returns a new Tree for the given config structure.
func NewTree(c *config.Config) *Tree {
return &Tree{config: c}
}
// 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
}
// Flatten takes the entire module tree and flattens it into a single
// namespace in *config.Config with no module imports.
//
// Validate is called here implicitly, since it is important that semantic
// checks pass before flattening the configuration. Otherwise, encapsulation
// breaks in horrible ways and the errors that come out the other side
// will be surprising.
func (t *Tree) Flatten() (*config.Config, error) {
return nil, nil
}
// 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 "<root>"
}
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 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.
update := mode == GetModeUpdate
for _, m := range modules {
if _, ok := children[m.Name]; ok {
return fmt.Errorf(
"module %s: duplicated. module names must be unique", m.Name)
}
source, err := Detect(m.Source, t.config.Dir)
if err != nil {
return fmt.Errorf("module %s: %s", m.Name, err)
}
if mode > GetModeNone {
// Get the module since we specified we should
if err := s.Get(source, update); err != nil {
return err
}
}
// Get the directory where this module is so we can load it
dir, ok, err := s.Dir(source)
if err != nil {
return err
}
if !ok {
return fmt.Errorf(
"module %s: not found, may need to be downloaded", m.Name)
}
// Load the configuration
c, err := config.LoadDir(dir)
if err != nil {
return fmt.Errorf(
"module %s: %s", m.Name, err)
}
children[m.Name] = NewTree(c)
children[m.Name].name = m.Name
}
// 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
}
// String gives a nice output to describe the tree.
func (t *Tree) String() string {
var result bytes.Buffer
result.WriteString(t.Name() + "\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 := &ValidateError{Name: []string{t.Name()}}
// Validate our configuration first.
if err := t.config.Validate(); err != nil {
newErr.Err = err
return newErr
}
// 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.(*ValidateError)
if !ok {
// Unknown error, just return...
return err
}
// Append ourselves to the error and then return
verr.Name = append(verr.Name, t.Name())
return 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
varMap := make(map[string]struct{})
for _, v := range tree.config.Variables {
varMap[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.Err = fmt.Errorf(
"module %s: %s is not a valid parameter",
m.Name, k)
return newErr
}
}
}
return nil
}
// ValidateError is an error returned by Tree.Validate if an error occurs
// with validation.
type ValidateError struct {
Name []string
Err error
}
func (e *ValidateError) Error() string {
// Build up the name
var buf bytes.Buffer
for _, n := range e.Name {
buf.WriteString(n)
buf.WriteString(".")
}
buf.Truncate(buf.Len() - 1)
// Format the value
return fmt.Sprintf("module %s: %s", buf.String(), e.Err)
}