Refactor according to DDD specs

[louisinger]

This PR refactor the feeder code to follow DDD architecture, it keeps the base implementation but adds a layer of abstraction and changes the structure of the code.

Domain
Basically there is three interfaces to understand:

• a Feed is a source of market prices information such as Kraken API for instance.
• a Target represents the thing that will change the market price.
• a TdexFeeder gets a slice of Feed and a slice of Target, it listens for feeds and then replicate data to targets.

See the scheme in README for a global overview

Ports
The ports package implements external interfaces. For now there is krakenWebSocket.go that implements a kraken WS feed and tdexDaemonPriceUpdater.go that implements the GRPC call of UpdateMarketPrice.

Application
Application package implements services used by the UI.

• The FeedService handles kraken web socket feed.
• The UpdaterService implements the domain.Target interface for the TDexDaemon.
• The FeederService takes a FeedService, creates a Feeder and target an UpdaterService --> this is the feederd implementation.

Adapters
The adapters pacakge only handle the configService that manage serialization and deserialization of Config JSON file and create a feederService depending of data inside it.

The PR also adds some unit testing + an integration test for feederd

The problem of Kraken web socket

To be clear: the feeder seems to work but I've some problem with socket reading.
I have taken over the method of the current version : the ReadMessages method of websocket package. This method has one drawback: it does not sort the messages received by Kraken. However, KrakenWS sends several types of messages (subscribe, heartbeat, prices etc...) --> so here, It seems that I receive only one "price" message from Kraken, and then I only receive "Heartbeat". I'm not aware off web sockets so I probably miss something.

what I would do: Use go-kraken instead of websocket package. This is a go lib that manages all the Kraken web sockets stuffs. What's your opinion about it ?

Questions / TO DO

Interval: @francismars you have implemented an interval for each Market --> I do not replicate that because I don't understand why we need an interval for each market ? And why the user should modify it ? Please enlighten me on this.

Daemon macaroon: this was not used. I confess that I haven't done much research on this point but it seems to me that Macaroon is not implemented yet?

Global project structure: I'm note sure of what I did with project structure (all in internal because there is not "exported" packages for me)

DDD: First time that I try DDD alone so be indulgent and do not hesitate to criticize the architecture of what I did --> I would like progress on this.

@sekulicd @tiero @francismars @altafan please review

it closes #10

[tiero]

I would Log the price and the kraken ticker everytime we push an update into the daemon

[tiero]

I tested the feeder against a local tdex-daemon

config.json

{
    "daemon_endpoint": "127.0.0.1:9000",
    "kraken_ws_endpoint": "ws.kraken.com",
    "markets": [
        {
            "base_asset": "5ac9f65c0efcc4775e0baec4ec03abdde22473cd3cf33c0419ca290e0751b225",
            "quote_asset": "6be29b1596fd3c0424f4b6eadb09d01ffdc1757ff15ea12a48a1535a01906978",
            "kraken_ticker": "XBT/USDT",
            "interval": 1000
        }
    ]
}

My MarketPrice RPC request/response

{
"market": {
        "base_asset": "5ac9f65c0efcc4775e0baec4ec03abdde22473cd3cf33c0419ca290e0751b225",
        "quote_asset": "6be29b1596fd3c0424f4b6eadb09d01ffdc1757ff15ea12a48a1535a01906978"
      },
  "type": 0,
  "amount": 100,
  "asset": "5ac9f65c0efcc4775e0baec4ec03abdde22473cd3cf33c0419ca290e0751b225"
}
{
  "prices": [
    {
      "price": {
        "base_price": 0.0000545214643352665,
        "quote_price": 0.0000545214643352665
      },
      "fee": {
        "basis_point": "25"
      },
      "amount": "0",
      "asset": "6be29b1596fd3c0424f4b6eadb09d01ffdc1757ff15ea12a48a1535a01906978"
    }
  ]
}

[tiero]

Gracefully handle the shutdown

2020/12/09 19:55:20 waiting 1s until reconnect...
2020/12/09 19:55:21 reconnect attempt 1/5
2020/12/09 19:55:21 connecting ws to wss://ws.kraken.com
2020/12/09 19:55:21 socket disconnect
2020/12/09 19:55:21 waiting 1s until reconnect...
2020/12/09 19:55:22 reconnect attempt 1/5
2020/12/09 19:55:22 socket disconnect
2020/12/09 19:55:22 waiting 1s until reconnect...
2020/12/09 19:55:22 websocket connection closed
2020/12/09 19:55:22 reconnect failed: websocket connection closed
2020/12/09 19:55:22 socket disconnect: websocket connection closed
2020/12/09 19:55:22 Shutdown listen upstream
2020/12/09 19:55:22 connecting ws to wss://ws.kraken.com
2020/12/09 19:55:22 Shutdown listen upstream
2020/12/09 19:55:22 Shutdown listen upstream
2020/12/09 19:55:23 Shutdown control heartbeat
2020/12/09 19:55:23 Shutdown control heartbeat
2020/12/09 19:55:23 reconnect attempt 1/5
2020/12/09 19:55:23 Shutdown listen disconnect
2020/12/09 19:55:23 Shutdown listen upstream
2020/12/09 19:55:23 websocket connection closed
2020/12/09 19:55:23 reconnect failed: websocket connection closed
2020/12/09 19:55:23 Shutdown control heartbeat
panic: send on closed channel

goroutine 71 [running]:
github.com/aopoltorzhicky/go_kraken/websocket.(*Client).close(...)
	/home/tiero/go/pkg/mod/github.com/aopoltorzhicky/go_kraken/[email protected]/client.go:283
github.com/aopoltorzhicky/go_kraken/websocket.(*Client).exit(...)
	/home/tiero/go/pkg/mod/github.com/aopoltorzhicky/go_kraken/[email protected]/client.go:258
github.com/aopoltorzhicky/go_kraken/websocket.(*Client).reconnect(0xc0001d4140, 0x0, 0x0, 0x0, 0x0)
	/home/tiero/go/pkg/mod/github.com/aopoltorzhicky/go_kraken/[email protected]/client.go:245 +0x389
github.com/aopoltorzhicky/go_kraken/websocket.(*Client).listenDisconnect(0xc0001d4140)
	/home/tiero/go/pkg/mod/github.com/aopoltorzhicky/go_kraken/[email protected]/client.go:149 +0x345
created by github.com/aopoltorzhicky/go_kraken/websocket.(*Client).reset
	/home/tiero/go/pkg/mod/github.com/aopoltorzhicky/go_kraken/[email protected]/client.go:189 +0x58
make: *** [Makefile:44: run-linux] Error 2
tdex-feeder refactoring 🔒  ✏️ 1