packer-cn/packer/environment.go

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// The packer package contains the core components of Packer.
package packer
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import (
"errors"
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"fmt"
"log"
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"os"
"sort"
"strings"
)
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// The function type used to lookup Builder implementations.
type BuilderFunc func(name string) (Builder, error)
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// The function type used to lookup Command implementations.
type CommandFunc func(name string) (Command, error)
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// The function type used to lookup Hook implementations.
type HookFunc func(name string) (Hook, error)
// The function type used to lookup PostProcessor implementations.
type PostProcessorFunc func(name string) (PostProcessor, error)
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// The function type used to lookup Provisioner implementations.
type ProvisionerFunc func(name string) (Provisioner, error)
// ComponentFinder is a struct that contains the various function
// pointers necessary to look up components of Packer such as builders,
// commands, etc.
type ComponentFinder struct {
Builder BuilderFunc
Command CommandFunc
Hook HookFunc
PostProcessor PostProcessorFunc
Provisioner ProvisionerFunc
}
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// The environment interface provides access to the configuration and
// state of a single Packer run.
//
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// It allows for things such as executing CLI commands, getting the
// list of available builders, and more.
type Environment interface {
Builder(string) (Builder, error)
Cache() Cache
Cli([]string) (int, error)
Hook(string) (Hook, error)
PostProcessor(string) (PostProcessor, error)
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Provisioner(string) (Provisioner, error)
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Ui() Ui
}
// An implementation of an Environment that represents the Packer core
// environment.
type coreEnvironment struct {
cache Cache
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commands []string
components ComponentFinder
ui Ui
}
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// This struct configures new environments.
type EnvironmentConfig struct {
Cache Cache
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Commands []string
Components ComponentFinder
Ui Ui
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}
// DefaultEnvironmentConfig returns a default EnvironmentConfig that can
// be used to create a new enviroment with NewEnvironment with sane defaults.
func DefaultEnvironmentConfig() *EnvironmentConfig {
config := &EnvironmentConfig{}
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config.Commands = make([]string, 0)
config.Ui = &ReaderWriterUi{
Reader: os.Stdin,
Writer: os.Stdout,
}
return config
}
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// This creates a new environment
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func NewEnvironment(config *EnvironmentConfig) (resultEnv Environment, err error) {
if config == nil {
err = errors.New("config must be given to initialize environment")
return
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}
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env := &coreEnvironment{}
env.cache = config.Cache
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env.commands = config.Commands
env.components = config.Components
env.ui = config.Ui
// We want to make sure the components have valid function pointers.
// If a function pointer was not given, we assume that the function
// will just return a nil component.
if env.components.Builder == nil {
env.components.Builder = func(string) (Builder, error) { return nil, nil }
}
if env.components.Command == nil {
env.components.Command = func(string) (Command, error) { return nil, nil }
}
if env.components.Hook == nil {
env.components.Hook = func(string) (Hook, error) { return nil, nil }
}
if env.components.PostProcessor == nil {
env.components.PostProcessor = func(string) (PostProcessor, error) { return nil, nil }
}
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if env.components.Provisioner == nil {
env.components.Provisioner = func(string) (Provisioner, error) { return nil, nil }
}
// The default cache is just the system temporary directory
if env.cache == nil {
env.cache = &FileCache{CacheDir: os.TempDir()}
}
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resultEnv = env
return
}
// Returns a builder of the given name that is registered with this
// environment.
func (e *coreEnvironment) Builder(name string) (b Builder, err error) {
b, err = e.components.Builder(name)
if err != nil {
return
}
if b == nil {
err = fmt.Errorf("No builder returned for name: %s", name)
}
return
}
// Returns the cache for this environment
func (e *coreEnvironment) Cache() Cache {
return e.cache
}
// Returns a hook of the given name that is registered with this
// environment.
func (e *coreEnvironment) Hook(name string) (h Hook, err error) {
h, err = e.components.Hook(name)
if err != nil {
return
}
if h == nil {
err = fmt.Errorf("No hook returned for name: %s", name)
}
return
}
// Returns a PostProcessor for the given name that is registered with this
// environment.
func (e *coreEnvironment) PostProcessor(name string) (p PostProcessor, err error) {
p, err = e.components.PostProcessor(name)
if err != nil {
return
}
if p == nil {
err = fmt.Errorf("No post processor found for name: %s", name)
}
return
}
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// Returns a provisioner for the given name that is registered with this
// environment.
func (e *coreEnvironment) Provisioner(name string) (p Provisioner, err error) {
p, err = e.components.Provisioner(name)
if err != nil {
return
}
if p == nil {
err = fmt.Errorf("No provisioner returned for name: %s", name)
}
return
}
// Executes a command as if it was typed on the command-line interface.
// The return value is the exit code of the command.
func (e *coreEnvironment) Cli(args []string) (result int, err error) {
log.Printf("Environment.Cli: %#v\n", args)
// If we have no arguments, just short-circuit here and print the help
if len(args) == 0 {
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e.printHelp()
return 1, nil
}
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// This variable will track whether or not we're supposed to print
// the help or not.
isHelp := false
for _, arg := range args {
if arg == "-h" || arg == "--help" {
isHelp = true
break
}
}
// Trim up to the command name
for i, v := range args {
if v[0] != '-' {
args = args[i:]
break
}
}
log.Printf("command + args: %#v", args)
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version := args[0] == "version"
if !version {
for _, arg := range args {
if arg == "--version" || arg == "-v" {
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version = true
break
}
}
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}
var command Command
if version {
command = new(versionCommand)
}
if command == nil {
command, err = e.components.Command(args[0])
if err != nil {
return
}
// If we still don't have a command, show the help.
if command == nil {
log.Printf("Environment.CLI: command not found: %s\n", args[0])
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e.printHelp()
return 1, nil
}
}
// If we're supposed to print help, then print the help of the
// command rather than running it.
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if isHelp {
e.ui.Say(command.Help())
return 0, nil
}
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log.Printf("Executing command: %s\n", args[0])
return command.Run(e, args[1:]), nil
}
// Prints the CLI help to the UI.
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func (e *coreEnvironment) printHelp() {
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// Created a sorted slice of the map keys and record the longest
// command name so we can better format the output later.
i := 0
maxKeyLen := 0
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for _, command := range e.commands {
if len(command) > maxKeyLen {
maxKeyLen = len(command)
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}
i++
}
// Sort the keys
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sort.Strings(e.commands)
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e.ui.Say("usage: packer [--version] [--help] <command> [<args>]\n")
e.ui.Say("Available commands are:")
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for _, key := range e.commands {
var synopsis string
command, err := e.components.Command(key)
if err != nil {
synopsis = fmt.Sprintf("Error loading command: %s", err.Error())
} else if command == nil {
continue
} else {
synopsis = command.Synopsis()
}
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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
e.ui.Say(fmt.Sprintf(" %v %v", key, synopsis))
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}
}
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// Returns the UI for the environment. The UI is the interface that should
// be used for all communication with the outside world.
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func (e *coreEnvironment) Ui() Ui {
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return e.ui
}