add db replication support in backend and load-balancing in backend

backend-fcgiwrap/cgi-bin/add-client.py

@@ -1,11 +1,12 @@
 #!/usr/bin/python3
 import tarantool
 import cgi
+from connect_to_db import tarantool_connect
+
+s = tarantool_connect()
 
 form = cgi.FieldStorage()
 
-connection = tarantool.connect("db-tarantool", 3301)
-s = connection.space('maindb')
 
 
 print("Content-Type: text/html; charset=utf-8")    # HTML is following

backend-fcgiwrap/cgi-bin/change-client-money.py

@@ -1,11 +1,11 @@
 #!/usr/bin/python3
 import tarantool
 import cgi
+from connect_to_db import tarantool_connect
 
-form = cgi.FieldStorage()
+s = tarantool_connect()
 
-connection = tarantool.connect("db-tarantool", 3301)
-s = connection.space('maindb')
+form = cgi.FieldStorage()
 
 
 print("Content-Type: text/html; charset=utf-8")    # HTML is following

backend-fcgiwrap/cgi-bin/connect_to_db.py

@@ -0,0 +1,16 @@
+#!/usr/bin/python3
+import tarantool
+import random
+
+def tarantool_connect():
+    availble_db = ["db-tarantool", "db-tarantool2"]
+    random.shuffle(availble_db)  # for load balancing
+    try:
+        connection = tarantool.connect(availble_db[0], 3301)
+        return connection.space('maindb')
+    except:
+        connection = tarantool.connect(availble_db[1], 3301)
+        return connection.space('maindb')
+
+
+

backend-fcgiwrap/cgi-bin/delete-client.py

@@ -1,11 +1,12 @@
 #!/usr/bin/python3
 import tarantool
 import cgi
+from connect_to_db import tarantool_connect
+
+s = tarantool_connect()
 
 form = cgi.FieldStorage()
 
-connection = tarantool.connect("db-tarantool", 3301)
-s = connection.space('maindb')
 
 
 print("Content-Type: text/html; charset=utf-8")    # HTML is following

backend-fcgiwrap/cgi-bin/show-all.py

@@ -1,8 +1,8 @@
 #!/usr/bin/python3
 import tarantool
+from connect_to_db import tarantool_connect
 
-connection = tarantool.connect("db-tarantool", 3301)
-s = connection.space('maindb')
+s = tarantool_connect()
 
 
 print("Content-Type: text/html; charset=utf-8")    # HTML is following