Class: LiveKit::RegionFailoverMiddleware

Inherits:
Faraday::Middleware
  • Object
show all
Defined in:
lib/livekit/failover.rb

Overview

Faraday middleware that fails over to alternative LiveKit Cloud regions on a retryable error: any transport error or HTTP 5xx. A 4xx is returned immediately. The request body and headers are replayed intact against the next untried region, with exponential backoff.

Instance Method Summary collapse

Constructor Details

#initialize(app, options = {}) ⇒ RegionFailoverMiddleware

Returns a new instance of RegionFailoverMiddleware.



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# File 'lib/livekit/failover.rb', line 147

def initialize(app, options = {})
  super(app)
  @failover = options.fetch(:failover, true)
  # +force+ / +backoff_base+ are internal test-only knobs.
  @force = options.fetch(:force, false)
  @backoff_base = options.fetch(:backoff_base, Failover::BACKOFF_BASE)
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/livekit/failover.rb', line 155

def call(env)
  original_url = env.url.dup
  request_body = env.body

  # A per-request timeout override (e.g. for SIP dialing) travels as an
  # internal header; consume it so it isn't sent to the server. Otherwise
  # use the connection's configured timeout.
  timeout = env.request_headers.delete(Failover::TIMEOUT_HEADER)&.to_f
  timeout ||= env.request.timeout
  env.request.timeout = timeout if timeout

  request_headers = env.request_headers.dup
  max_attempts = Failover.attempts(@failover, original_url.host, @force, timeout)

  attempted = [Failover.host_key(original_url)]
  regions = nil
  current_url = original_url
  attempt = 0

  loop do
    is_last = attempt + 1 >= max_attempts
    env.url = current_url
    env.body = request_body

    response = nil
    error = nil
    begin
      response = @app.call(env)
    rescue Faraday::Error => e
      error = e
    end

    # Success or a non-retryable 4xx is terminal.
    return response if response && response.status < 500

    nxt = nil
    unless is_last
      regions ||= Failover.region_uris(original_url, request_headers)
      nxt = Failover.pick_next(regions, attempted)
    end

    if nxt.nil?
      return response if response
      raise error
    end

    reason = response ? "status #{response.status}" : (error&.message || 'error')
    warn("livekit API request to #{current_url.host} failed (#{reason}), " \
         "retrying with fallback url #{nxt}")
    sleep(@backoff_base * (2**attempt))
    attempted << Failover.host_key(nxt)
    # Swap only the region's scheme/host/port, preserving the request path.
    current_url = original_url.dup
    current_url.scheme = nxt.scheme
    current_url.host = nxt.host
    current_url.port = nxt.port
    attempt += 1
  end
end