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"
"os"
)
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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 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
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
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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components ComponentFinder
ui Ui
}
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// This struct configures new environments.
type EnvironmentConfig struct {
Cache Cache
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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{}
config.Ui = &BasicUi{
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Reader: os.Stdin,
Writer: os.Stdout,
ErrorWriter: 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
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.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
}
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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
}