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Copy pathclient.go
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179 lines (147 loc) · 3.41 KB
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package consul
import (
"crypto/md5"
"encoding/json"
"errors"
"fmt"
"time"
consulapi "github.com/hashicorp/consul/api"
multierror "github.com/hashicorp/go-multierror"
"github.com/hashicorp/terraform/state"
"github.com/hashicorp/terraform/state/remote"
)
const (
lockSuffix = "/.lock"
lockInfoSuffix = "/.lockinfo"
)
// RemoteClient is a remote client that stores data in Consul.
type RemoteClient struct {
Client *consulapi.Client
Path string
consulLock *consulapi.Lock
lockCh <-chan struct{}
}
func (c *RemoteClient) Get() (*remote.Payload, error) {
pair, _, err := c.Client.KV().Get(c.Path, nil)
if err != nil {
return nil, err
}
if pair == nil {
return nil, nil
}
md5 := md5.Sum(pair.Value)
return &remote.Payload{
Data: pair.Value,
MD5: md5[:],
}, nil
}
func (c *RemoteClient) Put(data []byte) error {
kv := c.Client.KV()
_, err := kv.Put(&consulapi.KVPair{
Key: c.Path,
Value: data,
}, nil)
return err
}
func (c *RemoteClient) Delete() error {
kv := c.Client.KV()
_, err := kv.Delete(c.Path, nil)
return err
}
func (c *RemoteClient) putLockInfo(info *state.LockInfo) error {
info.Path = c.Path
info.Created = time.Now().UTC()
kv := c.Client.KV()
_, err := kv.Put(&consulapi.KVPair{
Key: c.Path + lockInfoSuffix,
Value: info.Marshal(),
}, nil)
return err
}
func (c *RemoteClient) getLockInfo() (*state.LockInfo, error) {
path := c.Path + lockInfoSuffix
pair, _, err := c.Client.KV().Get(path, nil)
if err != nil {
return nil, err
}
if pair == nil {
return nil, nil
}
li := &state.LockInfo{}
err = json.Unmarshal(pair.Value, li)
if err != nil {
return nil, fmt.Errorf("error unmarshaling lock info: %s", err)
}
return li, nil
}
func (c *RemoteClient) Lock(info *state.LockInfo) (string, error) {
select {
case <-c.lockCh:
// We had a lock, but lost it.
// Since we typically only call lock once, we shouldn't ever see this.
return "", errors.New("lost consul lock")
default:
if c.lockCh != nil {
// we have an active lock already
return "", nil
}
}
if c.consulLock == nil {
opts := &consulapi.LockOptions{
Key: c.Path + lockSuffix,
// We currently don't procide any options to block terraform and
// retry lock acquisition, but we can wait briefly in case the
// lock is about to be freed.
LockWaitTime: time.Second,
LockTryOnce: true,
}
lock, err := c.Client.LockOpts(opts)
if err != nil {
return "", err
}
c.consulLock = lock
}
lockErr := &state.LockError{}
lockCh, err := c.consulLock.Lock(make(chan struct{}))
if err != nil {
lockErr.Err = err
return "", lockErr
}
if lockCh == nil {
lockInfo, e := c.getLockInfo()
if e != nil {
lockErr.Err = e
return "", lockErr
}
lockErr.Info = lockInfo
return "", lockErr
}
c.lockCh = lockCh
err = c.putLockInfo(info)
if err != nil {
if unlockErr := c.Unlock(info.ID); unlockErr != nil {
err = multierror.Append(err, unlockErr)
}
return "", err
}
return info.ID, nil
}
func (c *RemoteClient) Unlock(id string) error {
// this doesn't use the lock id, because the lock is tied to the consul client.
if c.consulLock == nil || c.lockCh == nil {
return nil
}
select {
case <-c.lockCh:
return errors.New("consul lock was lost")
default:
}
err := c.consulLock.Unlock()
c.lockCh = nil
kv := c.Client.KV()
_, delErr := kv.Delete(c.Path+lockInfoSuffix, nil)
if delErr != nil {
err = multierror.Append(err, delErr)
}
return err
}