147 lines
3.3 KiB
Go
147 lines
3.3 KiB
Go
package packer
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import (
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"fmt"
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"sync"
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"time"
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)
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// A provisioner is responsible for installing and configuring software
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// on a machine prior to building the actual image.
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type Provisioner interface {
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// Prepare is called with a set of configurations to setup the
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// internal state of the provisioner. The multiple configurations
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// should be merged in some sane way.
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Prepare(...interface{}) error
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// Provision is called to actually provision the machine. A UI is
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// given to communicate with the user, and a communicator is given that
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// is guaranteed to be connected to some machine so that provisioning
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// can be done.
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Provision(Ui, Communicator) error
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// Cancel is called to cancel the provisioning. This is usually called
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// while Provision is still being called. The Provisioner should act
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// to stop its execution as quickly as possible in a race-free way.
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Cancel()
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}
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// A Hook implementation that runs the given provisioners.
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type ProvisionHook struct {
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// The provisioners to run as part of the hook. These should already
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// be prepared (by calling Prepare) at some earlier stage.
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Provisioners []Provisioner
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lock sync.Mutex
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runningProvisioner Provisioner
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}
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// Runs the provisioners in order.
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func (h *ProvisionHook) Run(name string, ui Ui, comm Communicator, data interface{}) error {
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defer func() {
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h.lock.Lock()
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defer h.lock.Unlock()
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h.runningProvisioner = nil
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}()
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for _, p := range h.Provisioners {
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h.lock.Lock()
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h.runningProvisioner = p
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h.lock.Unlock()
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if err := p.Provision(ui, comm); err != nil {
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return err
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}
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}
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return nil
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}
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// Cancels the privisioners that are still running.
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func (h *ProvisionHook) Cancel() {
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h.lock.Lock()
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defer h.lock.Unlock()
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if h.runningProvisioner != nil {
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h.runningProvisioner.Cancel()
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}
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}
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// PausedProvisioner is a Provisioner implementation that pauses before
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// the provisioner is actually run.
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type PausedProvisioner struct {
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PauseBefore time.Duration
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Provisioner Provisioner
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cancelCh chan struct{}
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doneCh chan struct{}
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lock sync.Mutex
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}
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func (p *PausedProvisioner) Prepare(raws ...interface{}) error {
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return p.Provisioner.Prepare(raws...)
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}
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func (p *PausedProvisioner) Provision(ui Ui, comm Communicator) error {
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p.lock.Lock()
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cancelCh := make(chan struct{})
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p.cancelCh = cancelCh
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// Setup the done channel, which is trigger when we're done
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doneCh := make(chan struct{})
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defer close(doneCh)
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p.doneCh = doneCh
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p.lock.Unlock()
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defer func() {
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p.lock.Lock()
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defer p.lock.Unlock()
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if p.cancelCh == cancelCh {
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p.cancelCh = nil
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}
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if p.doneCh == doneCh {
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p.doneCh = nil
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}
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}()
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// Use a select to determine if we get cancelled during the wait
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ui.Say(fmt.Sprintf("Pausing %s before the next provisioner...", p.PauseBefore))
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select {
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case <-time.After(p.PauseBefore):
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case <-cancelCh:
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return nil
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}
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provDoneCh := make(chan error, 1)
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go p.provision(provDoneCh, ui, comm)
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select {
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case err := <-provDoneCh:
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return err
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case <-cancelCh:
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p.Provisioner.Cancel()
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return <-provDoneCh
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}
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}
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func (p *PausedProvisioner) Cancel() {
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var doneCh chan struct{}
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p.lock.Lock()
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if p.cancelCh != nil {
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close(p.cancelCh)
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p.cancelCh = nil
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}
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if p.doneCh != nil {
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doneCh = p.doneCh
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}
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p.lock.Unlock()
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<-doneCh
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}
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func (p *PausedProvisioner) provision(result chan<- error, ui Ui, comm Communicator) {
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result <- p.Provisioner.Provision(ui, comm)
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}
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