terraform/state/local.go

314 lines
7.2 KiB
Go

package state
import (
"bytes"
"encoding/json"
"fmt"
"io"
"io/ioutil"
"os"
"path/filepath"
"sync"
"time"
multierror "github.com/hashicorp/go-multierror"
"github.com/hashicorp/terraform/terraform"
)
// LocalState manages a state storage that is local to the filesystem.
type LocalState struct {
mu sync.Mutex
// Path is the path to read the state from. PathOut is the path to
// write the state to. If PathOut is not specified, Path will be used.
// If PathOut already exists, it will be overwritten.
Path string
PathOut string
// the file handle corresponding to PathOut
stateFileOut *os.File
// While the stateFileOut will correspond to the lock directly,
// store and check the lock ID to maintain a strict state.Locker
// implementation.
lockID string
// created is set to true if stateFileOut didn't exist before we created it.
// This is mostly so we can clean up empty files during tests, but doesn't
// hurt to remove file we never wrote to.
created bool
state *terraform.State
readState *terraform.State
written bool
}
// SetState will force a specific state in-memory for this local state.
func (s *LocalState) SetState(state *terraform.State) {
s.mu.Lock()
defer s.mu.Unlock()
s.state = state.DeepCopy()
s.readState = state.DeepCopy()
}
// StateReader impl.
func (s *LocalState) State() *terraform.State {
return s.state.DeepCopy()
}
// WriteState for LocalState always persists the state as well.
// TODO: this should use a more robust method of writing state, by first
// writing to a temp file on the same filesystem, and renaming the file over
// the original.
//
// StateWriter impl.
func (s *LocalState) WriteState(state *terraform.State) error {
s.mu.Lock()
defer s.mu.Unlock()
if s.stateFileOut == nil {
if err := s.createStateFiles(); err != nil {
return nil
}
}
defer s.stateFileOut.Sync()
s.state = state.DeepCopy() // don't want mutations before we actually get this written to disk
if s.readState != nil && s.state != nil {
// We don't trust callers to properly manage serials. Instead, we assume
// that a WriteState is always for the next version after what was
// most recently read.
s.state.Serial = s.readState.Serial
}
if _, err := s.stateFileOut.Seek(0, io.SeekStart); err != nil {
return err
}
if err := s.stateFileOut.Truncate(0); err != nil {
return err
}
if state == nil {
// if we have no state, don't write anything else.
return nil
}
if !s.state.MarshalEqual(s.readState) {
s.state.Serial++
}
if err := terraform.WriteState(s.state, s.stateFileOut); err != nil {
return err
}
s.written = true
return nil
}
// PersistState for LocalState is a no-op since WriteState always persists.
//
// StatePersister impl.
func (s *LocalState) PersistState() error {
return nil
}
// StateRefresher impl.
func (s *LocalState) RefreshState() error {
s.mu.Lock()
defer s.mu.Unlock()
if s.PathOut == "" {
s.PathOut = s.Path
}
var reader io.Reader
// The s.Path file is only OK to read if we have not written any state out
// (in which case the same state needs to be read in), and no state output file
// has been opened (possibly via a lock) or the input path is different
// than the output path.
// This is important for Windows, as if the input file is the same as the
// output file, and the output file has been locked already, we can't open
// the file again.
if !s.written && (s.stateFileOut == nil || s.Path != s.PathOut) {
// we haven't written a state file yet, so load from Path
f, err := os.Open(s.Path)
if err != nil {
// It is okay if the file doesn't exist, we treat that as a nil state
if !os.IsNotExist(err) {
return err
}
// we need a non-nil reader for ReadState and an empty buffer works
// to return EOF immediately
reader = bytes.NewBuffer(nil)
} else {
defer f.Close()
reader = f
}
} else {
// no state to refresh
if s.stateFileOut == nil {
return nil
}
// we have a state file, make sure we're at the start
s.stateFileOut.Seek(0, io.SeekStart)
reader = s.stateFileOut
}
state, err := terraform.ReadState(reader)
// if there's no state we just assign the nil return value
if err != nil && err != terraform.ErrNoState {
return err
}
s.state = state
s.readState = s.state.DeepCopy()
return nil
}
// Lock implements a local filesystem state.Locker.
func (s *LocalState) Lock(info *LockInfo) (string, error) {
s.mu.Lock()
defer s.mu.Unlock()
if s.stateFileOut == nil {
if err := s.createStateFiles(); err != nil {
return "", err
}
}
if s.lockID != "" {
return "", fmt.Errorf("state %q already locked", s.stateFileOut.Name())
}
if err := s.lock(); err != nil {
info, infoErr := s.lockInfo()
if infoErr != nil {
err = multierror.Append(err, infoErr)
}
lockErr := &LockError{
Info: info,
Err: err,
}
return "", lockErr
}
s.lockID = info.ID
return s.lockID, s.writeLockInfo(info)
}
func (s *LocalState) Unlock(id string) error {
s.mu.Lock()
defer s.mu.Unlock()
if s.lockID == "" {
return fmt.Errorf("LocalState not locked")
}
if id != s.lockID {
idErr := fmt.Errorf("invalid lock id: %q. current id: %q", id, s.lockID)
info, err := s.lockInfo()
if err != nil {
idErr = multierror.Append(idErr, err)
}
return &LockError{
Err: idErr,
Info: info,
}
}
os.Remove(s.lockInfoPath())
fileName := s.stateFileOut.Name()
unlockErr := s.unlock()
s.stateFileOut.Close()
s.stateFileOut = nil
s.lockID = ""
// clean up the state file if we created it an never wrote to it
stat, err := os.Stat(fileName)
if err == nil && stat.Size() == 0 && s.created {
os.Remove(fileName)
}
return unlockErr
}
// Open the state file, creating the directories and file as needed.
func (s *LocalState) createStateFiles() error {
if s.PathOut == "" {
s.PathOut = s.Path
}
// yes this could race, but we only use it to clean up empty files
if _, err := os.Stat(s.PathOut); os.IsNotExist(err) {
s.created = true
}
// Create all the directories
if err := os.MkdirAll(filepath.Dir(s.PathOut), 0755); err != nil {
return err
}
f, err := os.OpenFile(s.PathOut, os.O_RDWR|os.O_CREATE, 0666)
if err != nil {
return err
}
s.stateFileOut = f
return nil
}
// return the path for the lockInfo metadata.
func (s *LocalState) lockInfoPath() string {
stateDir, stateName := filepath.Split(s.Path)
if stateName == "" {
panic("empty state file path")
}
if stateName[0] == '.' {
stateName = stateName[1:]
}
return filepath.Join(stateDir, fmt.Sprintf(".%s.lock.info", stateName))
}
// lockInfo returns the data in a lock info file
func (s *LocalState) lockInfo() (*LockInfo, error) {
path := s.lockInfoPath()
infoData, err := ioutil.ReadFile(path)
if err != nil {
return nil, err
}
info := LockInfo{}
err = json.Unmarshal(infoData, &info)
if err != nil {
return nil, fmt.Errorf("state file %q locked, but could not unmarshal lock info: %s", s.Path, err)
}
return &info, nil
}
// write a new lock info file
func (s *LocalState) writeLockInfo(info *LockInfo) error {
path := s.lockInfoPath()
info.Path = s.Path
info.Created = time.Now().UTC()
err := ioutil.WriteFile(path, info.Marshal(), 0600)
if err != nil {
return fmt.Errorf("could not write lock info for %q: %s", s.Path, err)
}
return nil
}