Storage has now it's own package.

Remove global `sessions` map and use configured storage.
Add a `types` package so both `pwd` and `storage` can access without
circular dependencies.
Now the session is prepared when requested and not on load.

storage/file.go

@@ -0,0 +1,150 @@
+package storage
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"strings"
+	"sync"
+
+	"github.com/play-with-docker/play-with-docker/pwd/types"
+)
+
+type storage struct {
+	rw   sync.Mutex
+	path string
+	db   map[string]*types.Session
+}
+
+func (store *storage) SessionGet(sessionId string) (*types.Session, error) {
+	store.rw.Lock()
+	defer store.rw.Unlock()
+
+	s, found := store.db[sessionId]
+	if !found {
+		return nil, fmt.Errorf("%s", notFound)
+	}
+
+	return s, nil
+}
+func (store *storage) SessionPut(s *types.Session) error {
+	store.rw.Lock()
+	defer store.rw.Unlock()
+
+	store.db[s.Id] = s
+
+	return store.save()
+}
+
+func (store *storage) InstanceFindByIP(ip string) (*types.Instance, error) {
+	store.rw.Lock()
+	defer store.rw.Unlock()
+
+	for _, s := range store.db {
+		for _, i := range s.Instances {
+			if i.IP == ip {
+				return i, nil
+			}
+		}
+	}
+
+	return nil, fmt.Errorf("%s", notFound)
+}
+
+func (store *storage) InstanceFindByAlias(sessionPrefix, alias string) (*types.Instance, error) {
+	store.rw.Lock()
+	defer store.rw.Unlock()
+
+	for id, s := range store.db {
+		if strings.HasPrefix(id, sessionPrefix) {
+			for _, i := range s.Instances {
+				if i.Alias == alias {
+					return i, nil
+				}
+			}
+		}
+	}
+
+	return nil, fmt.Errorf("%s", notFound)
+}
+
+func (store *storage) SessionCount() (int, error) {
+	store.rw.Lock()
+	defer store.rw.Unlock()
+
+	return len(store.db), nil
+}
+
+func (store *storage) InstanceCount() (int, error) {
+	store.rw.Lock()
+	defer store.rw.Unlock()
+
+	var ins int
+
+	for _, s := range store.db {
+		ins += len(s.Instances)
+	}
+
+	return ins, nil
+}
+
+func (store *storage) ClientCount() (int, error) {
+	store.rw.Lock()
+	defer store.rw.Unlock()
+
+	var cli int
+
+	for _, s := range store.db {
+		cli += len(s.Clients)
+	}
+
+	return cli, nil
+}
+
+func (store *storage) SessionDelete(sessionId string) error {
+	store.rw.Lock()
+	defer store.rw.Unlock()
+
+	delete(store.db, sessionId)
+	return store.save()
+}
+
+func (store *storage) load() error {
+	file, err := os.Open(store.path)
+
+	if err == nil {
+		decoder := json.NewDecoder(file)
+		err = decoder.Decode(&store.db)
+
+		if err != nil {
+			return err
+		}
+	} else {
+		store.db = map[string]*types.Session{}
+	}
+
+	file.Close()
+	return nil
+}
+
+func (store *storage) save() error {
+	file, err := os.Create(store.path)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+	encoder := json.NewEncoder(file)
+	err = encoder.Encode(&store.db)
+	return err
+}
+
+func NewFileStorage(path string) (StorageApi, error) {
+	s := &storage{path: path}
+
+	err := s.load()
+	if err != nil {
+		return nil, err
+	}
+
+	return s, nil
+}