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.

pwd/storage_mock_test.go

@@ -1,19 +1,63 @@
 package pwd
 
+import "github.com/play-with-docker/play-with-docker/pwd/types"
+
 type mockStorage struct {
-	save func() error
-	load func() error
+	sessionGet          func(sessionId string) (*types.Session, error)
+	sessionPut          func(s *types.Session) error
+	sessionCount        func() (int, error)
+	sessionDelete       func(sessionId string) error
+	instanceFindByAlias func(sessionPrefix, alias string) (*types.Instance, error)
+	instanceFindByIP    func(ip string) (*types.Instance, error)
+	instanceCount       func() (int, error)
+	clientCount         func() (int, error)
 }
 
-func (m *mockStorage) Save() error {
-	if m.save != nil {
-		return m.save()
+func (m *mockStorage) SessionGet(sessionId string) (*types.Session, error) {
+	if m.sessionGet != nil {
+		return m.sessionGet(sessionId)
+	}
+	return nil, nil
+}
+func (m *mockStorage) SessionPut(s *types.Session) error {
+	if m.sessionPut != nil {
+		return m.sessionPut(s)
 	}
 	return nil
 }
-func (m *mockStorage) Load() error {
-	if m.load != nil {
-		return m.load()
+func (m *mockStorage) SessionCount() (int, error) {
+	if m.sessionCount != nil {
+		return m.sessionCount()
+	}
+	return 0, nil
+}
+func (m *mockStorage) SessionDelete(sessionId string) error {
+	if m.sessionDelete != nil {
+		return m.sessionDelete(sessionId)
 	}
 	return nil
 }
+func (m *mockStorage) InstanceFindByAlias(sessionPrefix, alias string) (*types.Instance, error) {
+	if m.instanceFindByAlias != nil {
+		return m.instanceFindByAlias(sessionPrefix, alias)
+	}
+	return nil, nil
+}
+func (m *mockStorage) InstanceFindByIP(ip string) (*types.Instance, error) {
+	if m.instanceFindByIP != nil {
+		return m.instanceFindByIP(ip)
+	}
+	return nil, nil
+}
+func (m *mockStorage) InstanceCount() (int, error) {
+	if m.instanceCount != nil {
+		return m.instanceCount()
+	}
+	return 0, nil
+}
+func (m *mockStorage) ClientCount() (int, error) {
+	if m.clientCount != nil {
+		return m.clientCount()
+	}
+	return 0, nil
+}