144 lines
3.6 KiB
Go
144 lines
3.6 KiB
Go
// The packer package contains the core components of Packer.
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package packer
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import (
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"fmt"
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"os"
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"sort"
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"strings"
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)
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// A command is a runnable sub-command of the `packer` application.
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// When `packer` is called with the proper subcommand, this will be
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// called.
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//
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// The mapping of command names to command interfaces is in the
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// Environment struct.
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//
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// Run should run the actual command with the given environmet and
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// command-line arguments. It should return the exit status when it is
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// finished.
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//
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// Synopsis should return a one-line, short synopsis of the command.
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// This should be less than 50 characters ideally.
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type Command interface {
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Run(env *Environment, args []string) int
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Synopsis() string
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}
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// The environment struct contains all the state necessary for a single
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// instance of Packer.
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//
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// It is *not* a singleton, but generally a single environment is created
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// when Packer starts running to represent that Packer run. Technically,
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// if you're building a custom Packer binary, you could instantiate multiple
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// environments and run them in parallel.
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type Environment struct {
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builderFactory BuilderFactory
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command map[string]Command
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ui Ui
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}
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// This struct configures new environments.
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type EnvironmentConfig struct {
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BuilderFactory BuilderFactory
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Command map[string]Command
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Ui Ui
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}
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// This creates a new environment
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func NewEnvironment(config *EnvironmentConfig) *Environment {
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env := &Environment{}
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env.command = make(map[string]Command)
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if config != nil {
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for k, v := range config.Command {
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env.command[k] = v
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}
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env.builderFactory = config.BuilderFactory
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env.ui = config.Ui
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}
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if _, ok := env.command["build"]; !ok {
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env.command["build"] = new(buildCommand)
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}
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if _, ok := env.command["version"]; !ok {
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env.command["version"] = new(versionCommand)
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}
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if env.ui == nil {
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env.ui = &ReaderWriterUi{os.Stdin, os.Stdout}
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}
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return env
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}
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// Executes a command as if it was typed on the command-line interface.
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// The return value is the exit code of the command.
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func (e *Environment) Cli(args []string) int {
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if len(args) == 0 || args[0] == "--help" || args[0] == "-h" {
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e.PrintHelp()
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return 1
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}
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command, ok := e.command[args[0]]
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if !ok {
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// The command was not found. In this case, let's go through
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// the arguments and see if the user is requesting the version.
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for _, arg := range args {
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if arg == "--version" || arg == "-v" {
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command = e.command["version"]
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break
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}
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}
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// If we still don't have a command, show the help.
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if command == nil {
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e.PrintHelp()
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return 1
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}
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}
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return command.Run(e, args[1:])
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}
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// Prints the CLI help to the UI.
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func (e *Environment) PrintHelp() {
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// Created a sorted slice of the map keys and record the longest
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// command name so we can better format the output later.
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commandKeys := make([]string, len(e.command))
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i := 0
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maxKeyLen := 0
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for key, _ := range e.command {
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commandKeys[i] = key
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if len(key) > maxKeyLen {
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maxKeyLen = len(key)
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}
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i++
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}
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// Sort the keys
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sort.Strings(commandKeys)
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e.ui.Say("usage: packer [--version] [--help] <command> [<args>]\n\n")
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e.ui.Say("Available commands are:\n")
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for _, key := range commandKeys {
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command := e.command[key]
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// Pad the key with spaces so that they're all the same width
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key = fmt.Sprintf("%v%v", key, strings.Repeat(" ", maxKeyLen-len(key)))
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// Output the command and the synopsis
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e.ui.Say(" %v %v\n", key, command.Synopsis())
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}
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}
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// Returns the UI for the environment. The UI is the interface that should
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// be used for all communication with the outside world.
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func (e *Environment) Ui() Ui {
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return e.ui
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}
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