Ticker de Criptomoedas

Ticker de Criptomoedas

Construa um ticker de criptomoedas em tempo real com autenticação por API key e streaming WebSocket. Este tutorial demonstra segurança baseada em token, configuração de middleware e tratamento de WebSocket baseado em processos.

Visão Geral

• Troca de API key — POST de uma API key devolve um token bearer assinado com HMAC
• Middleware de token — Protege upgrades WebSocket através do token store
• Fan-out WebSocket — Um processo ticker transmite para múltiplos handlers de conexão
• Ativos estáticos — http.static serve o cliente do navegador
• SQLite — Armazena API keys; um memory store suporta o token store

Estrutura do Projeto

auth-ticker/
├── wippy.lock
└── src/
    ├── _index.yaml
    ├── auth_token.lua
    ├── ws_ticker.lua
    ├── ws_handler.lua
    ├── ticker.lua
    ├── migrate.lua
    └── public/
        └── index.html

Arquitetura

flowchart TB
    subgraph Clients
        Browser[Browser Client]
        API[API Client]
    end

    subgraph "HTTP Layer"
        Server[http.server<br/>gateway :8081]
        Static[http.static<br/>public/]

        subgraph "Public Router"
            CORS1[cors middleware]
            AuthEndpoint[auth_token<br/>POST /auth/token]
        end

        subgraph "WS Router /ws"
            CORS2[cors middleware]
            TokenAuth[token_auth middleware]
            WSEndpoint[ws_ticker<br/>GET /ws/ticker]
            WSRelay[websocket_relay]
        end
    end

    subgraph "Security Layer"
        TokenStore[security.token_store<br/>tokens]
        Policy[security.policy<br/>user_policy]
        MemStore[store.memory<br/>token_data]
    end

    subgraph "Storage"
        DB[db.sql.sqlite<br/>auth.db]
    end

    subgraph "Process Layer"
        Supervisor[process.supervisor<br/>processes]
        WSHandler[ws_handler<br/>per-connection]
        Ticker[ticker<br/>singleton]
    end

    subgraph "External"
        CryptoAPI[Crypto Price API]
    end

    %% Client connections
    Browser -->|"GET /"| Static
    API -->|"POST /auth/token"| CORS1
    Browser -->|"WS /ws/ticker"| CORS2

    %% API flow
    CORS1 --> AuthEndpoint
    AuthEndpoint -->|validate| TokenStore
    AuthEndpoint -->|"issue token"| API

    %% WS flow
    CORS2 --> TokenAuth
    TokenAuth -->|validate| TokenStore
    TokenAuth --> WSEndpoint
    WSEndpoint -->|spawn| Supervisor
    Supervisor --> WSHandler
    WSEndpoint --> WSRelay
    WSRelay <-->|"messages"| WSHandler

    %% Token store deps
    MemStore --> TokenStore
    Policy -->|attached to token| TokenStore

    %% Auth uses DB for API keys
    AuthEndpoint -->|lookup API key| DB

    %% Process communication
    WSHandler -->|subscribe| Ticker
    Ticker -->|broadcast| WSHandler
    WSRelay <-->|"ws frames"| Browser

    %% External
    Ticker -->|fetch prices| CryptoAPI

Fluxo de Segurança

1. Troca de API Key: Cliente faz POST da API key para /auth/token. Handler valida contra banco de dados, cria um ator com a user_policy e emite um token assinado com HMAC.

2. Autenticação por Token: Conexões WebSocket passam pelo middleware token_auth que valida o Bearer token e restaura o contexto de segurança (ator + políticas).

3. Criação de Processo: O endpoint WebSocket cria um processo handler. Como o token inclui a user_policy, o spawn é autorizado.

4. Roteamento de Mensagens: O middleware websocket_relay roteia frames WebSocket para o processo handler como mensagens.

Configuração

_index.yaml completo:

version: "1.0"
namespace: app

entries:
  # Banco de dados para API keys
  - name: db
    kind: db.sql.sqlite
    file: "./data/auth.db"
    lifecycle:
      auto_start: true

  # Store de backing para tokens
  - name: token_data
    kind: store.memory
    lifecycle:
      auto_start: true

  # Token store com assinatura HMAC
  - name: tokens
    kind: security.token_store
    store: app:token_data
    token_length: 32
    default_expiration: "1h"
    token_key: "demo-secret-key-change-in-production"

  # Política de segurança para usuários autenticados
  - name: user_policy
    kind: security.policy
    policy:
      actions: "*"
      resources: "*"
      effect: allow
    groups:
      - user

  # Host de processos
  - name: processes
    kind: process.host
    lifecycle:
      auto_start: true

  # Migração do banco de dados
  - name: migrate
    kind: process.lua
    source: file://migrate.lua
    method: main
    modules: [sql, logger, crypto]

  - name: migrate-service
    kind: process.service
    process: app:migrate
    host: app:processes
    lifecycle:
      auto_start: true

  # Broadcaster do ticker
  - name: ticker
    kind: process.lua
    source: file://ticker.lua
    method: main
    modules: [logger, time, json, crypto]

  - name: ticker-service
    kind: process.service
    process: app:ticker
    host: app:processes
    lifecycle:
      auto_start: true

  # Handler WebSocket (criado por conexão)
  - name: ws_handler
    kind: process.lua
    source: file://ws_handler.lua
    method: main
    modules: [logger, json]

  # Servidor HTTP
  - name: gateway
    kind: http.service
    addr: ":8081"
    lifecycle:
      auto_start: true

  # Router público (sem auth)
  - name: public_router
    kind: http.router
    meta:
      server: app:gateway
    middleware:
      - cors
    options:
      cors.allow.origins: "*"

  # Router WebSocket (com auth)
  - name: ws_router
    kind: http.router
    meta:
      server: app:gateway
    prefix: /ws
    middleware:
      - cors
      - token_auth
    options:
      cors.allow.origins: "*"
      token_auth.store: "app:tokens"
    post_middleware:
      - websocket_relay
    post_options:
      wsrelay.allowed.origins: "*"

  # Arquivos estáticos
  - name: public_fs
    kind: fs.directory
    directory: ./public

  - name: static
    kind: http.static
    meta:
      server: app:gateway
    path: /
    fs: app:public_fs
    static_options:
      spa: true
      index: index.html

  # Troca de token de auth
  - name: auth_token
    kind: function.lua
    source: file://auth_token.lua
    method: handler
    modules: [http, sql, crypto, security, json]

  - name: auth_token.endpoint
    kind: http.endpoint
    meta:
      router: app:public_router
    method: POST
    path: /auth/token
    func: app:auth_token

  # Endpoint do ticker WebSocket
  - name: ws_ticker
    kind: function.lua
    source: file://ws_ticker.lua
    method: handler
    modules: [http, json, security, logger]

  - name: ws_ticker.endpoint
    kind: http.endpoint
    meta:
      router: app:ws_router
    method: GET
    path: /ticker
    func: app:ws_ticker

Para produção, use token_key_env para ler a chave HMAC de uma variável de ambiente em vez de codificá-la. Veja Environment System.

Troca de Token

auth_token.lua - valida API keys e emite tokens assinados com HMAC:

local http = require("http")
local sql = require("sql")
local security = require("security")

local function handler()
    local req = http.request()
    local res = http.response()

    local body, parse_err = req:body_json()
    if parse_err then
        res:set_status(http.STATUS.BAD_REQUEST)
        res:write_json({error = "invalid JSON"})
        return
    end

    local api_key = body.api_key
    if not api_key or #api_key == 0 then
        res:set_status(http.STATUS.BAD_REQUEST)
        res:write_json({error = "api_key required"})
        return
    end

    local db, db_err = sql.get("app:db")
    if db_err then
        res:set_status(http.STATUS.INTERNAL_ERROR)
        res:write_json({error = "database unavailable"})
        return
    end

    local rows, query_err = db:query(
        "SELECT user_id, role FROM api_keys WHERE api_key = ?",
        {api_key}
    )
    db:release()

    if query_err then
        res:set_status(http.STATUS.INTERNAL_ERROR)
        res:write_json({error = "lookup failed"})
        return
    end
    if #rows == 0 then
        res:set_status(http.STATUS.UNAUTHORIZED)
        res:write_json({error = "invalid API key"})
        return
    end

    local user = rows[1]

    -- Criar ator com identidade do usuário
    local actor = security.new_actor("user:" .. user.user_id, {
        role = user.role,
        user_id = user.user_id
    })

    -- Anexar user_policy ao escopo
    local policy, _ = security.policy("app:user_policy")
    local scope = policy and security.new_scope({policy}) or security.new_scope()

    -- Emitir token assinado com HMAC
    local store, store_err = security.token_store("app:tokens")
    if store_err then
        res:set_status(http.STATUS.INTERNAL_ERROR)
        res:write_json({error = "token store unavailable"})
        return
    end

    local token, token_err = store:create(actor, scope, {
        expiration = "1h",
        meta = {ip = req:remote_addr()}
    })
    store:close()

    if token_err then
        res:set_status(http.STATUS.INTERNAL_ERROR)
        res:write_json({error = "token creation failed"})
        return
    end

    res:write_json({
        token = token,
        user_id = user.user_id,
        role = user.role,
        expires_in = 3600
    })
end

return { handler = handler }

Endpoint WebSocket

ws_ticker.lua - cria um processo handler para cada conexão autenticada:

local http = require("http")
local json = require("json")
local security = require("security")
local logger = require("logger")

local function handler()
    local req = http.request()
    local res = http.response()

    if req:method() ~= http.METHOD.GET then
        res:set_status(http.STATUS.METHOD_NOT_ALLOWED)
        res:write_json({error = "method not allowed"})
        return
    end

    -- Ator é definido pelo middleware token_auth
    local actor = security.actor()
    if not actor then
        res:set_status(http.STATUS.UNAUTHORIZED)
        res:write_json({error = "authentication required"})
        return
    end

    local user_id = actor:id()

    -- Criar processo handler (autorizado pela user_policy no token)
    local pid, err = process.spawn("app:ws_handler", "app:processes", user_id)
    if err then
        logger:error("spawn failed", {error = tostring(err)})
        res:set_status(http.STATUS.INTERNAL_ERROR)
        res:write_json({error = "failed to create handler"})
        return
    end

    -- Configurar websocket_relay para rotear mensagens para o handler
    res:set_header("X-WS-Relay", json.encode({
        target_pid = tostring(pid),
        metadata = {user_id = user_id, auth_time = os.time()}
    }))
end

return { handler = handler }

Handler de Conexão

O middleware websocket_relay automaticamente envia mensagens de ciclo de vida para o processo handler:

• ws.join - Conexão estabelecida, inclui client_pid para enviar respostas
• ws.message - Cliente enviou uma mensagem
• ws.leave - Conexão fechada (enviado automaticamente na desconexão)

ws_handler.lua - trata essas mensagens de ciclo de vida:

local logger = require("logger")
local json = require("json")

local function main(user_id)
    local inbox = process.inbox()
    local client_pid = nil
    local subscribed = false

    logger:info("handler started", {user_id = user_id})

    while true do
        local msg, ok = inbox:receive()
        if not ok then break end

        local topic = msg:topic()
        local data = msg:payload():data()

        if topic == "ws.join" then
            client_pid = data.client_pid

            -- Inscrever com nosso PID para monitoramento de crash
            process.send("ticker", "subscribe", {
                client_pid = client_pid,
                handler_pid = process.pid()
            })
            subscribed = true

            -- Enviar boas-vindas
            process.send(client_pid, "ws.send", {
                type = "text",
                data = json.encode({type = "welcome", user_id = user_id})
            })

            logger:info("client joined", {user_id = user_id, client_pid = client_pid})

        elseif topic == "ws.message" then
            local content = json.decode(data.data)
            if content and content.type == "ping" then
                process.send(client_pid, "ws.send", {
                    type = "text",
                    data = json.encode({type = "pong"})
                })
            end

        elseif topic == "ws.leave" then
            -- Relay envia isso automaticamente na desconexão
            logger:info("client left", {user_id = user_id, reason = data.reason})
            if subscribed then
                process.send("ticker", "unsubscribe", {handler_pid = process.pid()})
            end
            break
        end
    end

    return 0
end

return { main = main }

Broadcasting

ticker.lua - mantém inscrições e faz broadcast de atualizações de preço:

local logger = require("logger")
local time = require("time")
local json = require("json")
local crypto = require("crypto")

-- Mapeamento handler_pid -> client_pid
local subscriptions = {}

local prices = {
    ["BTC-USD"] = 42000.00,
    ["ETH-USD"] = 2500.00,
    ["SOL-USD"] = 95.00
}

local function broadcast(message)
    local data = json.encode(message)
    for _, client_pid in pairs(subscriptions) do
        process.send(client_pid, "ws.send", {type = "text", data = data})
    end
end

local function update_prices()
    for symbol, price in pairs(prices) do
        local bytes = crypto.random.bytes(2)
        local rand = (bytes:byte(1) * 256 + bytes:byte(2)) / 65535.0
        local factor = (rand - 0.5) * 0.002
        prices[symbol] = price * (1 + factor)
        prices[symbol] = tonumber(string.format("%.2f", prices[symbol]))
    end
end

local function get_updates()
    local updates = {}
    for symbol, price in pairs(prices) do
        table.insert(updates, {symbol = symbol, price = price, timestamp = os.time()})
    end
    return updates
end

local function main()
    local inbox = process.inbox()
    local events = process.events()

    local ticker, ticker_err = time.ticker("1s")
    if ticker_err then
        logger:error("failed to create ticker", {error = tostring(ticker_err)})
        return 1
    end
    local tick_ch = ticker:response()

    process.registry.register("ticker")
    logger:info("ticker started", {pid = process.pid()})

    while true do
        local r = channel.select {
            inbox:case_receive(),
            events:case_receive(),
            tick_ch:case_receive()
        }

        if r.channel == tick_ch then
            update_prices()
            if next(subscriptions) then
                broadcast({type = "ticker", data = get_updates()})
            end

        elseif r.channel == events then
            local event = r.value
            if event.kind == process.event.EXIT then
                -- Handler saiu, remover inscrição
                if subscriptions[event.from] then
                    logger:info("handler exited", {handler_pid = event.from})
                    subscriptions[event.from] = nil
                end
            end

        else
            local msg = r.value
            local topic = msg:topic()
            local data = msg:payload():data()

            if topic == "subscribe" then
                local handler_pid = data.handler_pid
                local client_pid = data.client_pid

                subscriptions[handler_pid] = client_pid
                process.monitor(handler_pid)

                logger:info("subscribed", {handler_pid = handler_pid, client_pid = client_pid})

                process.send(client_pid, "ws.send", {
                    type = "text",
                    data = json.encode({type = "ticker", data = get_updates()})
                })

            elseif topic == "unsubscribe" then
                subscriptions[data.handler_pid] = nil
                logger:info("unsubscribed", {handler_pid = data.handler_pid})
            end
        end
    end
end

return { main = main }

Migração do Banco de Dados

migrate.lua - cria a tabela de API keys e gera uma key demo:

local sql = require("sql")
local logger = require("logger")
local crypto = require("crypto")

local function main()
    local db, err = sql.get("app:db")
    if err then
        logger:error("failed to connect", {error = tostring(err)})
        return 1
    end

    local _, exec_err = db:execute([[
        CREATE TABLE IF NOT EXISTS api_keys (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            api_key TEXT UNIQUE NOT NULL,
            user_id TEXT NOT NULL,
            role TEXT NOT NULL DEFAULT 'user',
            created_at INTEGER NOT NULL
        )
    ]])

    if exec_err then
        db:release()
        logger:error("migration failed", {error = tostring(exec_err)})
        return 1
    end

    -- Verificar se key demo existe
    local rows, _ = db:query("SELECT api_key FROM api_keys WHERE user_id = ?", {"demo"})
    if #rows == 0 then
        local demo_key, key_err = crypto.random.string(32)
        if key_err then
            db:release()
            return 1
        end

        db:execute(
            "INSERT INTO api_keys (api_key, user_id, role, created_at) VALUES (?, ?, ?, ?)",
            {demo_key, "demo", "user", os.time()}
        )
        logger:info("demo API key created", {api_key = demo_key})
    else
        logger:info("demo API key exists", {api_key = rows[1].api_key})
    end

    db:release()
    return 0
end

return { main = main }

Executando

wippy init
wippy run

Abra http://localhost:8081 e insira a API key demo mostrada nos logs.

Próximos Passos

• WebSocket Relay - Configuração de middleware
• Security Module - Atores, políticas, token stores
• Process Management - Criação e mensagens de processos