Game servers pool

September 26, 2019 · View on GitHub

Why

Necessary to track which game servers are available for new games
Different game servers can have different ways to authenticate (tokens, passwords, etc.)
Game servers can be served in different clouds (Amazon Web Services, Google Cloud, Microsoft Azure, etc.)

Benefits of using

All inner logic around instantiating new game servers for endusers is hidden
Game server only registers or updates the existing information about itself
Can be scaled up independently

Dependencies

Authorization / Authentication microservice

Entity relationship diagram

Server table

Field name	Field type	Constraints	Description
id	UUID	PK	A database unique object identifier
host	VARCHAR	NOT NULL	IP address of the server
port	Integer	NOT NULL	The listened port by the server
available_slots	Integer	NOT NULL	Number of available slots for players
credentials	JSON (dict)	NOT NULL	The data used for connecting to the server
game_mode	VARCHAR	NOT NULL	Type of served games

API Endpoints

Method	Endpoint	Usage	Returns
GET	/game-servers-pool/api/health-check	Health check endpoint for API Gateways	"OK"

RabbitMQ exchanges and queues

Queues

Queue name	Queue options	Exchange name	Usage	Returns
game-servers-pool.server.register	durable=True, passive=False, exclusive=False, auto_delete=False	open-matchmaking.game-server-pool.server.register.direct	Registers a new game server or updates all information about it	A unique server ID or a validation error
game-servers-pool.server.retrieve	durable=True, passive=False, exclusive=False, auto_delete=False	open-matchmaking.game-server-pool.server.retrieve.direct	Gets a server with credentials to connect	Server with credentials
game-servers-pool.server.update	durable=True, passive=False, exclusive=False, auto_delete=False	open-matchmaking.game-server-pool.server.update.direct	Updates an infomation about available slots for games	The updated information about the server

For registering a new game server a developer should send a message to the game-servers-pool.server.register queue with content inside in JSON format and content_type=application/json in headers. The content contains the following fields:

Field name	Description	Type
id	Stores a unique identifier of the registered microservice. Not required by default.	UUID as string
host	IP address of the server.	String
port	The listened port by the server.	Integer
available-slots	Number of available slots for players.	Integer
credentials	The data used for connecting to the server.	Object
game-mode	Stores an information about the served type of games.	String

An example of a request for registering a new server (after processing by API gateway / reverse proxy):

{
  "host": "127.0.0.1",
  "port": "5000",
  "available-slots": 100,
  "credentials": {
      "token": "secret_token"
  },
  "game-mode": "team-deathmatch"
}

A request for updating an information about the server (when the server knows his the unique ID after registering) look almost the same, except the specified id field in the request:

{
  "id": "b188eb61-d19b-4c6b-b73b-ee744fda61c6",
  "host": "127.0.0.1",
  "port": "5000",
  "available-slots": 150,
  "credentials": {
      "token": "secret_token"
  },
  "game-mode": "team-deathmatch"
}

An example of the response for the valid request:

{
  "content": {
      "id": "b188eb61-d19b-4c6b-b73b-ee744fda61c6"
  },
  "event-name": "register-new-server"
}

An example of the response with the validation error:

{
  "error": {
      "type": "ValidationError",
      "details": {
          "host": ["Field can't be empty."]
      }
  },
  "event-name": "register-new-server"
}

Receiving a server with credentials

For registering a new game server a developer should send a message to the game-servers-pool.server.retrieve queue with content inside in JSON format and content_type=application/json in headers. The content contains the following fields:

Field name	Parent	Description	Type
required-slots		Requested an amount of slots for the new game session.	Integer
game-mode		Supported game type by a server that we're searching for.	String

Request:

By a client to API gateway / reverse proxy

{
  "url": "api/v1/game-servers-pool/retrieve",
  "content": {
    "required-slots": 10,
    "game-mode": "team-deathmatch"
  },
  "token": "a unique token",
  "event-name": "get-server"
}

Between microservices

{
  "required-slots": 10,
  "game-mode": "team-deathmatch"
}

An example of the response (success):

{
  "content": {
      "host": "127.0.0.1",
      "port": 5000,
      "credentials": {
          "token": "secret_token"
      }
  },
  "event-name": "get-server"
}