terraform/scripts/generate-plugins.go

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// Generate Plugins is a small program that updates the lists of plugins in
// command/internal_plugin_list.go so they will be compiled into the main
// terraform binary.
package main
import (
"fmt"
"go/ast"
"go/parser"
"go/token"
"io/ioutil"
"log"
"os"
"path/filepath"
"sort"
"strings"
)
const target = "command/internal_plugin_list.go"
func main() {
wd, _ := os.Getwd()
if filepath.Base(wd) != "terraform" {
log.Fatalf("This program must be invoked in the terraform project root; in %s", wd)
}
//// Collect all of the data we need about plugins we have in the project
//providers, err := discoverProviders()
//if err != nil {
// log.Fatalf("Failed to discover providers: %s", err)
//}
provisioners, err := discoverProvisioners()
if err != nil {
log.Fatalf("Failed to discover provisioners: %s", err)
}
// Do some simple code generation and templating
output := source
output = strings.Replace(output, "IMPORTS", makeImports(nil, provisioners), 1)
//output = strings.Replace(output, "PROVIDERS", makeProviderMap(providers), 1)
output = strings.Replace(output, "PROVISIONERS", makeProvisionerMap(provisioners), 1)
// TODO sort the lists of plugins so we are not subjected to random OS ordering of the plugin lists
// Write our generated code to the command/plugin.go file
file, err := os.Create(target)
defer file.Close()
if err != nil {
log.Fatalf("Failed to open %s for writing: %s", target, err)
}
_, err = file.WriteString(output)
if err != nil {
log.Fatalf("Failed writing to %s: %s", target, err)
}
log.Printf("Generated %s", target)
}
type plugin struct {
Package string // Package name from ast remoteexec
PluginName string // Path via deriveName() remote-exec
TypeName string // Type of plugin provisioner
Path string // Relative import path builtin/provisioners/remote-exec
ImportName string // See deriveImport() remoteexecprovisioner
}
// makeProviderMap creates a map of providers like this:
//
// var InternalProviders = map[string]plugin.ProviderFunc{
// "aws": aws.Provider,
// "azurerm": azurerm.Provider,
// "cloudflare": cloudflare.Provider,
func makeProviderMap(items []plugin) string {
output := ""
for _, item := range items {
output += fmt.Sprintf("\t\"%s\": %s.%s,\n", item.PluginName, item.ImportName, item.TypeName)
}
return output
}
// makeProvisionerMap creates a map of provisioners like this:
//
2017-05-21 17:01:53 +02:00
// "chef": chefprovisioner.Provisioner,
// "salt-masterless": saltmasterlessprovisioner.Provisioner,
// "file": fileprovisioner.Provisioner,
// "local-exec": localexecprovisioner.Provisioner,
// "remote-exec": remoteexecprovisioner.Provisioner,
//
func makeProvisionerMap(items []plugin) string {
output := ""
for _, item := range items {
output += fmt.Sprintf("\t\"%s\": %s.%s,\n", item.PluginName, item.ImportName, item.TypeName)
}
return output
}
func makeImports(providers, provisioners []plugin) string {
plugins := []string{}
for _, provider := range providers {
plugins = append(plugins, fmt.Sprintf("\t%s \"github.com/hashicorp/terraform/%s\"\n", provider.ImportName, filepath.ToSlash(provider.Path)))
}
for _, provisioner := range provisioners {
plugins = append(plugins, fmt.Sprintf("\t%s \"github.com/hashicorp/terraform/%s\"\n", provisioner.ImportName, filepath.ToSlash(provisioner.Path)))
}
// Make things pretty
sort.Strings(plugins)
return strings.Join(plugins, "")
}
// listDirectories recursively lists directories under the specified path
func listDirectories(path string) ([]string, error) {
names := []string{}
items, err := ioutil.ReadDir(path)
if err != nil {
return names, err
}
for _, item := range items {
// We only want directories
if item.IsDir() {
if item.Name() == "testdata" {
continue
}
currentDir := filepath.Join(path, item.Name())
names = append(names, currentDir)
// Do some recursion
subNames, err := listDirectories(currentDir)
if err == nil {
names = append(names, subNames...)
}
}
}
return names, nil
}
// deriveName determines the name of the plugin relative to the specified root
// path.
func deriveName(root, full string) string {
short, _ := filepath.Rel(root, full)
bits := strings.Split(short, string(os.PathSeparator))
return strings.Join(bits, "-")
}
// deriveImport will build a unique import identifier based on packageName and
// the result of deriveName(). This is important for disambigutating between
// providers and provisioners that have the same name. This will be something
// like:
//
// remote-exec -> remoteexecprovisioner
//
// which is long, but is deterministic and unique.
func deriveImport(typeName, derivedName string) string {
return strings.Replace(derivedName, "-", "", -1) + strings.ToLower(typeName)
}
// discoverTypesInPath searches for types of typeID in path using go's ast and
// returns a list of plugins it finds.
func discoverTypesInPath(path, typeID, typeName string) ([]plugin, error) {
pluginTypes := []plugin{}
dirs, err := listDirectories(path)
if err != nil {
return pluginTypes, err
}
for _, dir := range dirs {
fset := token.NewFileSet()
goPackages, err := parser.ParseDir(fset, dir, nil, parser.AllErrors)
if err != nil {
return pluginTypes, fmt.Errorf("Failed parsing directory %s: %s", dir, err)
}
for _, goPackage := range goPackages {
ast.PackageExports(goPackage)
ast.Inspect(goPackage, func(n ast.Node) bool {
switch x := n.(type) {
case *ast.FuncDecl:
// If we get a function then we will check the function name
// against typeName and the function return type (Results)
// against typeID.
//
// There may be more than one return type but in the target
// case there should only be one. Also the return type is a
// ast.SelectorExpr which means we have multiple nodes.
// We'll read all of them as ast.Ident (identifier), join
// them via . to get a string like terraform.ResourceProvider
// and see if it matches our expected typeID
//
// This is somewhat verbose but prevents us from identifying
// the wrong types if the function name is amiguous or if
// there are other subfolders added later.
if x.Name.Name == typeName && len(x.Type.Results.List) == 1 {
node := x.Type.Results.List[0].Type
typeIdentifiers := []string{}
ast.Inspect(node, func(m ast.Node) bool {
switch y := m.(type) {
case *ast.Ident:
typeIdentifiers = append(typeIdentifiers, y.Name)
}
// We need all of the identifiers to join so we
// can't break early here.
return true
})
if strings.Join(typeIdentifiers, ".") == typeID {
derivedName := deriveName(path, dir)
pluginTypes = append(pluginTypes, plugin{
Package: goPackage.Name,
PluginName: derivedName,
ImportName: deriveImport(x.Name.Name, derivedName),
TypeName: x.Name.Name,
Path: dir,
})
}
}
case *ast.TypeSpec:
// In the simpler case we will simply check whether the type
// declaration has the name we were looking for.
if x.Name.Name == typeID {
derivedName := deriveName(path, dir)
pluginTypes = append(pluginTypes, plugin{
Package: goPackage.Name,
PluginName: derivedName,
ImportName: deriveImport(x.Name.Name, derivedName),
TypeName: x.Name.Name,
Path: dir,
})
// The AST stops parsing when we return false. Once we
// find the symbol we want we can stop parsing.
return false
}
}
return true
})
}
}
return pluginTypes, nil
}
func discoverProviders() ([]plugin, error) {
path := "./builtin/providers"
typeID := "terraform.ResourceProvider"
typeName := "Provider"
return discoverTypesInPath(path, typeID, typeName)
}
func discoverProvisioners() ([]plugin, error) {
path := "./builtin/provisioners"
typeID := "terraform.ResourceProvisioner"
typeName := "Provisioner"
return discoverTypesInPath(path, typeID, typeName)
}
const source = `//
// This file is automatically generated by scripts/generate-plugins.go -- Do not edit!
//
package command
import (
IMPORTS
"github.com/hashicorp/terraform/plugin"
)
var InternalProviders = map[string]plugin.ProviderFunc{}
var InternalProvisioners = map[string]plugin.ProvisionerFunc{
PROVISIONERS
}
`