Add ACME store

Signed-off-by: Emile Vauge <emile@vauge.com>

acme/localStore.go

@@ -0,0 +1,97 @@
+package acme
+
+import (
+	"encoding/json"
+	"fmt"
+	"github.com/containous/traefik/cluster"
+	"github.com/containous/traefik/log"
+	"io/ioutil"
+	"sync"
+)
+
+var _ cluster.Store = (*LocalStore)(nil)
+
+// LocalStore is a store using a file as storage
+type LocalStore struct {
+	file        string
+	storageLock sync.RWMutex
+	account     *Account
+}
+
+// NewLocalStore create a LocalStore
+func NewLocalStore(file string) *LocalStore {
+	return &LocalStore{
+		file:        file,
+		storageLock: sync.RWMutex{},
+	}
+}
+
+// Get atomically a struct from the file storage
+func (s *LocalStore) Get() cluster.Object {
+	s.storageLock.RLock()
+	defer s.storageLock.RUnlock()
+	return s.account
+}
+
+// Load loads file into store
+func (s *LocalStore) Load() (cluster.Object, error) {
+	s.storageLock.Lock()
+	defer s.storageLock.Unlock()
+	account := &Account{}
+	file, err := ioutil.ReadFile(s.file)
+	if err != nil {
+		return nil, err
+	}
+	if err := json.Unmarshal(file, &account); err != nil {
+		return nil, err
+	}
+	account.Init()
+	s.account = account
+	log.Infof("Loaded ACME config from store %s", s.file)
+	return account, nil
+}
+
+// func (s *LocalStore) saveAccount(account *Account) error {
+// 	s.storageLock.Lock()
+// 	defer s.storageLock.Unlock()
+// 	// write account to file
+// 	data, err := json.MarshalIndent(account, "", "  ")
+// 	if err != nil {
+// 		return err
+// 	}
+// 	return ioutil.WriteFile(s.file, data, 0644)
+// }
+
+// Begin creates a transaction with the KV store.
+func (s *LocalStore) Begin() (cluster.Transaction, cluster.Object, error) {
+	s.storageLock.Lock()
+	return &localTransaction{LocalStore: s}, s.account, nil
+}
+
+var _ cluster.Transaction = (*localTransaction)(nil)
+
+type localTransaction struct {
+	*LocalStore
+	dirty bool
+}
+
+// Commit allows to set an object in the file storage
+func (t *localTransaction) Commit(object cluster.Object) error {
+	t.LocalStore.account = object.(*Account)
+	defer t.storageLock.Unlock()
+	if t.dirty {
+		return fmt.Errorf("Transaction already used. Please begin a new one.")
+	}
+
+	// write account to file
+	data, err := json.MarshalIndent(object, "", "  ")
+	if err != nil {
+		return err
+	}
+	return ioutil.WriteFile(t.file, data, 0644)
+	if err != nil {
+		return err
+	}
+	t.dirty = true
+	return nil
+}