terraform/communicator/communicator.go

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package communicator
import (
"context"
"fmt"
"io"
"log"
"sync/atomic"
"time"
"github.com/hashicorp/terraform/communicator/remote"
"github.com/hashicorp/terraform/communicator/ssh"
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"github.com/hashicorp/terraform/communicator/winrm"
"github.com/hashicorp/terraform/terraform"
)
// Communicator is an interface that must be implemented by all communicators
// used for any of the provisioners
type Communicator interface {
// Connect is used to setup the connection
Connect(terraform.UIOutput) error
// Disconnect is used to terminate the connection
Disconnect() error
// Timeout returns the configured connection timeout
Timeout() time.Duration
// ScriptPath returns the configured script path
ScriptPath() string
// Start executes a remote command in a new session
Start(*remote.Cmd) error
// Upload is used to upload a single file
Upload(string, io.Reader) error
// UploadScript is used to upload a file as a executable script
UploadScript(string, io.Reader) error
// UploadDir is used to upload a directory
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UploadDir(string, string) error
}
// New returns a configured Communicator or an error if the connection type is not supported
func New(s *terraform.InstanceState) (Communicator, error) {
connType := s.Ephemeral.ConnInfo["type"]
switch connType {
case "ssh", "": // The default connection type is ssh, so if connType is empty use ssh
return ssh.New(s)
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case "winrm":
return winrm.New(s)
default:
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return nil, fmt.Errorf("connection type '%s' not supported", connType)
}
}
// maxBackoffDelay is the maximum delay between retry attempts
var maxBackoffDelay = 20 * time.Second
var initialBackoffDelay = time.Second
// Fatal is an interface that error values can return to halt Retry
type Fatal interface {
FatalError() error
}
// Retry retries the function f until it returns a nil error, a Fatal error, or
// the context expires.
func Retry(ctx context.Context, f func() error) error {
// container for atomic error value
type errWrap struct {
E error
}
// Try the function in a goroutine
var errVal atomic.Value
doneCh := make(chan struct{})
go func() {
defer close(doneCh)
delay := time.Duration(0)
for {
// If our context ended, we want to exit right away.
select {
case <-ctx.Done():
return
case <-time.After(delay):
}
// Try the function call
err := f()
// return if we have no error, or a FatalError
done := false
switch e := err.(type) {
case nil:
done = true
case Fatal:
err = e.FatalError()
done = true
}
errVal.Store(errWrap{err})
if done {
return
}
log.Printf("[WARN] retryable error: %v", err)
delay *= 2
if delay == 0 {
delay = initialBackoffDelay
}
if delay > maxBackoffDelay {
delay = maxBackoffDelay
}
log.Printf("[INFO] sleeping for %s", delay)
}
}()
// Wait for completion
select {
case <-ctx.Done():
case <-doneCh:
}
var lastErr error
// Check if we got an error executing
if ev, ok := errVal.Load().(errWrap); ok {
lastErr = ev.E
}
// Check if we have a context error to check if we're interrupted or timeout
switch ctx.Err() {
case context.Canceled:
return fmt.Errorf("interrupted - last error: %v", lastErr)
case context.DeadlineExceeded:
return fmt.Errorf("timeout - last error: %v", lastErr)
}
if lastErr != nil {
return lastErr
}
return nil
}