Req Token bucket

Mix.install([
  {:req, "~> 0.4.9"},
  {:nimble_parsec, "~> 1.4"},
  # {:dummy_graph_server, path: "C:\\github\\chgeuer\\_resiliency\\ex_simulated_graph_server"}
  {:dummy_graph_server, github: "chgeuer/ex_simulated_graph_server"}
])

Section

Trying to inject a plugin into Req, that waits with making a request until a token is available, and updates the token bucket after the request with the remaining tokens.

• https://learn.microsoft.com/en-us/azure/governance/resource-graph/concepts/guidance-for-throttled-requests

defmodule InfiniteLoop do
  def loop(req) do
    %Req.Response{status: 200, body: body} = req |> Req.get!()
    IO.puts(body)
    loop(req)
  end
end

When this Livebook loads, there’s a Bandit server listening on port 4000, which has a rate limiter. By clicking “Re-evaluate” on the cell below, you can issue multiple requests…

Req.get!(url: "http://127.0.0.1:4000/")

However, this cell issues requests in an endless loop (and uses a client-side rate limiter, which respects the server’s limits).

Req.new(url: "http://127.0.0.1:4000/")
|> ReqTokenBarrier.attach_now_token_barrier()
|> InfiniteLoop.loop()