terraform/backend/remote-state/gcs/client.go

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package gcs
import (
"encoding/json"
"fmt"
"io/ioutil"
"strconv"
"cloud.google.com/go/storage"
multierror "github.com/hashicorp/go-multierror"
"github.com/hashicorp/terraform/states/remote"
"github.com/hashicorp/terraform/states/statemgr"
"golang.org/x/net/context"
)
// remoteClient is used by "state/remote".State to read and write
// blobs representing state.
// Implements "state/remote".ClientLocker
type remoteClient struct {
storageContext context.Context
storageClient *storage.Client
bucketName string
stateFilePath string
lockFilePath string
encryptionKey []byte
}
func (c *remoteClient) Get() (payload *remote.Payload, err error) {
stateFileReader, err := c.stateFile().NewReader(c.storageContext)
if err != nil {
if err == storage.ErrObjectNotExist {
return nil, nil
} else {
return nil, fmt.Errorf("Failed to open state file at %v: %v", c.stateFileURL(), err)
}
}
defer stateFileReader.Close()
stateFileContents, err := ioutil.ReadAll(stateFileReader)
if err != nil {
return nil, fmt.Errorf("Failed to read state file from %v: %v", c.stateFileURL(), err)
}
stateFileAttrs, err := c.stateFile().Attrs(c.storageContext)
if err != nil {
return nil, fmt.Errorf("Failed to read state file attrs from %v: %v", c.stateFileURL(), err)
}
result := &remote.Payload{
Data: stateFileContents,
MD5: stateFileAttrs.MD5,
}
return result, nil
}
func (c *remoteClient) Put(data []byte) error {
err := func() error {
stateFileWriter := c.stateFile().NewWriter(c.storageContext)
if _, err := stateFileWriter.Write(data); err != nil {
return err
}
return stateFileWriter.Close()
}()
if err != nil {
return fmt.Errorf("Failed to upload state to %v: %v", c.stateFileURL(), err)
}
return nil
}
func (c *remoteClient) Delete() error {
if err := c.stateFile().Delete(c.storageContext); err != nil {
return fmt.Errorf("Failed to delete state file %v: %v", c.stateFileURL(), err)
}
return nil
}
// Lock writes to a lock file, ensuring file creation. Returns the generation
// number, which must be passed to Unlock().
func (c *remoteClient) Lock(info *statemgr.LockInfo) (string, error) {
// update the path we're using
// we can't set the ID until the info is written
info.Path = c.lockFileURL()
infoJson, err := json.Marshal(info)
if err != nil {
return "", err
}
lockFile := c.lockFile()
w := lockFile.If(storage.Conditions{DoesNotExist: true}).NewWriter(c.storageContext)
err = func() error {
if _, err := w.Write(infoJson); err != nil {
return err
}
return w.Close()
}()
if err != nil {
return "", c.lockError(fmt.Errorf("writing %q failed: %v", c.lockFileURL(), err))
}
info.ID = strconv.FormatInt(w.Attrs().Generation, 10)
return info.ID, nil
}
func (c *remoteClient) Unlock(id string) error {
gen, err := strconv.ParseInt(id, 10, 64)
if err != nil {
return fmt.Errorf("Lock ID should be numerical value, got '%s'", id)
}
if err := c.lockFile().If(storage.Conditions{GenerationMatch: gen}).Delete(c.storageContext); err != nil {
return c.lockError(err)
}
return nil
}
func (c *remoteClient) lockError(err error) *statemgr.LockError {
lockErr := &statemgr.LockError{
Err: err,
}
info, infoErr := c.lockInfo()
if infoErr != nil {
lockErr.Err = multierror.Append(lockErr.Err, infoErr)
} else {
lockErr.Info = info
}
return lockErr
}
// lockInfo reads the lock file, parses its contents and returns the parsed
// LockInfo struct.
func (c *remoteClient) lockInfo() (*statemgr.LockInfo, error) {
r, err := c.lockFile().NewReader(c.storageContext)
if err != nil {
return nil, err
}
defer r.Close()
rawData, err := ioutil.ReadAll(r)
if err != nil {
return nil, err
}
info := &statemgr.LockInfo{}
if err := json.Unmarshal(rawData, info); err != nil {
return nil, err
}
// We use the Generation as the ID, so overwrite the ID in the json.
// This can't be written into the Info, since the generation isn't known
// until it's written.
attrs, err := c.lockFile().Attrs(c.storageContext)
if err != nil {
return nil, err
}
info.ID = strconv.FormatInt(attrs.Generation, 10)
return info, nil
}
func (c *remoteClient) stateFile() *storage.ObjectHandle {
h := c.storageClient.Bucket(c.bucketName).Object(c.stateFilePath)
if len(c.encryptionKey) > 0 {
return h.Key(c.encryptionKey)
}
return h
}
func (c *remoteClient) stateFileURL() string {
return fmt.Sprintf("gs://%v/%v", c.bucketName, c.stateFilePath)
}
func (c *remoteClient) lockFile() *storage.ObjectHandle {
return c.storageClient.Bucket(c.bucketName).Object(c.lockFilePath)
}
func (c *remoteClient) lockFileURL() string {
return fmt.Sprintf("gs://%v/%v", c.bucketName, c.lockFilePath)
}