Ports Packer code to load CLI configuration and external plugins

cliconfig.go

@@ -0,0 +1,9 @@
+package main
+
+// ConfigFile returns the default path to the configuration file. On
+// Unix-like systems this is the ".terraformrc" file in the home directory.
+// On Windows, this is the "terraform.rc" file in the application data
+// directory.
+func ConfigFile() (string, error) {
+    return configFile()
+}

cliconfig_unix.go

@@ -0,0 +1,45 @@
+// +build darwin freebsd linux netbsd openbsd
+
+package main
+
+import (
+	"bytes"
+	"errors"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+)
+
+func configFile() (string, error) {
+	dir, err := configDir()
+	if err != nil {
+		return "", err
+	}
+
+	return filepath.Join(dir, ".terraformrc"), nil
+}
+
+func configDir() (string, error) {
+	// First prefer the HOME environmental variable
+	if home := os.Getenv("HOME"); home != "" {
+		log.Printf("Detected home directory from env var: %s", home)
+		return home, nil
+	}
+
+	// If that fails, try the shell
+	var stdout bytes.Buffer
+	cmd := exec.Command("sh", "-c", "eval echo ~$USER")
+	cmd.Stdout = &stdout
+	if err := cmd.Run(); err != nil {
+		return "", err
+	}
+
+	result := strings.TrimSpace(stdout.String())
+	if result == "" {
+		return "", errors.New("blank output")
+	}
+
+	return result, nil
+}

cliconfig_windows.go

@@ -0,0 +1,37 @@
+// +build windows
+
+package main
+
+import (
+	"path/filepath"
+	"syscall"
+	"unsafe"
+)
+
+var (
+	shell         = syscall.MustLoadDLL("Shell32.dll")
+	getFolderPath = shell.MustFindProc("SHGetFolderPathW")
+)
+
+const CSIDL_APPDATA = 26
+
+func configFile() (string, error) {
+	dir, err := configDir()
+	if err != nil {
+		return "", err
+	}
+
+	return filepath.Join(dir, "terraform.rc"), nil
+}
+
+func configDir() (string, error) {
+	b := make([]uint16, syscall.MAX_PATH)
+
+	// See: http://msdn.microsoft.com/en-us/library/windows/desktop/bb762181(v=vs.85).aspx
+	r, _, err := getFolderPath.Call(0, CSIDL_APPDATA, 0, 0, uintptr(unsafe.Pointer(&b[0])))
+	if uint32(r) != 0 {
+		return "", err
+	}
+
+	return syscall.UTF16ToString(b), nil
+}

main.go

@@ -107,6 +107,24 @@ func wrappedMain() int {
 		HelpWriter: os.Stdout,
 	}
 
+	clicfgFile, err := cliConfigFile()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error loading user configuration: \n\n%s\n", err)
+		return 1
+	}
+
+	usrcfg, err := LoadConfig(clicfgFile)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error loading user configuration: \n\n%s\n", err)
+		return 1
+	}
+
+	config = *config.Merge(usrcfg)
+
+	// Initialize the TFConfig settings for the commands...
+	ContextOpts.Providers = config.ProviderFactories()
+	ContextOpts.Provisioners = config.ProvisionerFactories()
+
 	exitCode, err := cli.Run()
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "Error executing CLI: %s\n", err.Error())
@@ -116,6 +134,38 @@ func wrappedMain() int {
 	return exitCode
 }
 
+func cliConfigFile() (string, error) {
+	mustExist := true
+	configFilePath := os.Getenv("TERRAFORM_CONFIG")
+	if configFilePath == "" {
+		var err error
+		configFilePath, err = configFile()
+		mustExist = false
+
+		if err != nil {
+			log.Printf("Error detecting default CLI config file path: %s", err)
+		}
+	}
+
+	log.Printf("Attempting to open CLI config file: %s", configFilePath)
+	f, err := os.Open(configFilePath)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			return "", err
+		}
+
+		if mustExist {
+			return "", err
+		}
+
+		log.Println("File doesn't exist, but doesn't need to. Ignoring.")
+		return "", nil
+	}
+	defer f.Close()
+
+	return configFilePath, nil
+}
+
 // copyOutput uses output prefixes to determine whether data on stdout
 // should go to stdout or stderr. This is due to panicwrap using stderr
 // as the log and error channel.