View Source IdempotencyPlug
Plug that makes POST and PATCH requests idempotent using Idempotency-Key
HTTP header.
Follows the IETF Idempotency-Key HTTP Header Field specifcation draft.
installation
Installation
Add idempotency_plug
to your list of dependencies in mix.exs
:
def deps do
[
{:idempotency_plug, "~> 0.1"}
]
end
usage
Usage
First add the request tracker to your supervision tree:
defmodule MyApp.Application do
# ..
def start(_type, _args) do
children = [
{IdempotencyPlug.RequestTracker, [name: MyAppWeb.RequestTracker]}
# ...
]
Supervisor.start_link(children, strategy: :one_for_one, name: MyApp.Supervisor)
end
end
Now add the plug to your pipeline:
defmodule MyAppWeb.Router do
# ...
pipeline :api do
plug :accepts, ["json"]
plug IdempotencyPlug, tracker: MyAppWeb.RequestTracker
end
# ...
end
All POST and PATCH requests will now be idempotent using the Idempotency-Key
HTTP header value, storing responses with the default ETS store.
persisted-store
Persisted store
The ETS store is not persisted, so it's not production ready. Instead let's change the store to use Ecto.
First run mix idempotency_plug.ecto.gen.migration
.
Now update the configuration for the request tracker:
{IdempotencyPlug.RequestTracker, [store: {IdempotencyPlug.EctoStore, repo: MyApp.Repo}]}
You can also implement your own idempotent request store by using the behaviour in IdempotencyPlug.Store
.
customize-response
Customize response
The plug handling can be customized by using the IdempotencyPlug.Handler
behaviour:
defmodule MyAppWeb.IdempotencyPlugHandler do
@behaviour IdempotencyPlug.Handler
import Phoenix.Controller
import Plug.Conn
@impl true
def idempotent_id(conn, id) do
IdempotencyPlug.Handler.idempotent_id(conn, id)
end
@impl true
def resp_error(conn, error) do
conn
|> put_status(IdempotencyPlug.Handler.status(error))
|> json(%{error: IdempotencyPlug.Handler.message(error)})
end
end
Remember to update the plug opts:
plug IdempotencyPlug,
tracker: MyAppWeb.RequestTracker,
handler: MyAppWeb.IdempotencyPlugHandler
scope-idempotency-key
Scope Idempotency-Key
If you authenticate an user in your API you will need to scope the Idempotency-Key
to the authenticated user:
defmodule MyAppWeb.IdempotencyPlugHandler do
@behaviour IdempotencyPlug.Handler
@impl true
def idempotent_id(conn, id) do
"#{conn.assigns.current_user.id}:#{id}"
end
@impl true
def resp_error(conn, error) do
IdempotencyPlug.Handler.resp_error(conn, error)
end
end
license
LICENSE
(The MIT License)
Copyright (c) 2023 Dan Schultzer & the Contributors
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.