Throttle
A general throttle utility. Mainly used to throttle inbound or outbound requests.
Installation
Add the following to your list of dependencies in mix.exs:
def deps do
[{:throttle, "~> 0.1.2"}]
endSetup
As of now, Throttle only provides a Redis-backed cache. To configure your Redis connection, please add the following to config/config.exs.
config :redis_connection_pool, [
host: "127.0.0.1",
port: 6379,
password: "",
db: 0,
reconnect: :no_reconnect,
pool_name: :"Redis.Pool",
pool_size: 10,
pool_max_overflow: 1
]Or use with the full_url option.
config :redis_connection_pool, [
full_url: "redis://127.0.0.1:6379",
reconnect: :no_reconnect,
pool_name: :"Redis.Pool",
pool_size: 10,
pool_max_overflow: 1
]You can also add throttle contexts to your config. This will allow us to access them by atom-only in the future.
config :throttle, [
contexts: [
# This would create a throttle context keyed under "example1" that allows 3 requests per second.
example1: {"example1", :rps, 3}
# This would create a throttle context keyed under "example2" that allows 30 requests per minute.
example2: {"example2", :rpm, 30}
# This would create a throttle context keyed under "example3" that allows 300 requests per hour.
example2: {"example3", :rph, 300}
# This would create a throttle context keyed under "example4" that allows 1 request every 3 seconds.
example2: {"example3", :interval, 3}
# This would create a throttle context keyed under "example5" using a leaky bucket that adds 1 token every second (rate),
# to a maximum of 40 (max), with each request costing 2 tokens (cost).
example2: {"example3", :bucket, [rate: 1, max: 40, cost: 2]}
]
]Usage
Throttle provides a number of ways in which to control requests. They are:
- Requests per second (rps)
- Requests per minute (rpm)
- Requests per hour (rph)
- Seconds Between Request (interval)
- Leaky Bucket (bucket)
Assuming we use one of our above contexts, we can now start using our throttles:
case Throttle.allow?(:example2) do
{:ok, result} -> IO.puts "OK"
{:error, result} -> IO.puts "Error"
endUsing config contexts means that each request is made under the same key. In the example above, this would be "example2".
Alternatively, we can simply pass a context directly into the allow? function.
key = "1" # This could be a user id
case Throttle.allow?({key, :rps, 3}) do
{:ok, result} -> IO.puts "OK"
{:error, result} -> IO.puts "Error"
endIn all cases, a context must be structured as follows:
{key, type, value} = {"key", :rps, 3}Using With Plug
Throttle provides a plug that can be used for API throttling. It can be used as follows:
defmodule MyRouter do
use Plug.Router
plug Throttle.Plug, {"mysite", :bucket, [rate: 1, max: 40, cost: 2]}
plug :match
plug :dispatch
match _ do
send_resp(conn, 200, "hello")
end
endThe above would end up creating a leaky bucket throttle. The key would be a join between "mysite" and the IP address of the incoming request.
