Exfile

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File upload persistence and processing for Phoenix / Plug, with a focus on flexibility and extendability.

Inspired heavily by Refile. If you use Ruby, check Refile out. I like it. ๐Ÿ‘

Requires Elixir ~> 1.2.0. At this point, it is only tested against the most recent version of Elixir.

Exfile is used in a production environment at this point, but it still may go through some breaking changes. Exfile aims to adheres to semver v2.0.

Storage Adapters

Exfile supports storage backend adapters. A local filesystem based adapter is included (Exfile.Backend.FileSystem) as an example.

File Processors

Exfile also supports file processors / filters. If youโ€™re working with images, exfile-imagemagick is recommended.

  • exfile-imagemagick โ€” uses ImageMagick to resize, crop, and transform images.
  • exfile-encryption โ€” encrypts files before uploading them and decrypts them after downloading them from the backend.

Usage Overview

Exfile applies transforms on the fly; it only stores the original file in the storage backend. It is expected to be behind a caching HTTP proxy and/or a caching CDN for performance. Because dimensions and processors are determined by the path, it is authenticated with a HMAC to make sure it is not tampered with.

The Phoenix integration comes with two helper functions, exfile_url and exfile_path.

For example, the following code will return a path to the userโ€™s profile_picture that is converted to JPEG (if not already in JPEG format) and limited to 1024 ร— 1024.

exfile_url(@conn, @user.profile_picture, format: "jpg", processor: "limit", processor_args: [1024, 1024])

For more information about what processors are available for images, check out exfile-imagemagick.

Installation

  1. Add exfile to your list of dependencies in mix.exs:

        def deps do
          [{:exfile, "~> 0.3.2"}]
        end
        ```
    
  2. Ensure exfile is started before your application:

        def application do
          [applications: [:exfile]]
        end
        ```
    
  3. Mount the Exfile routes in your router.

Phoenix

defmodule MyApp.Router do
  use MyApp.Web, :router

  foward "/attachments", Exfile.Router
  ...

To use the exfile_path and exfile_url helpers, include the Exfile.Phoenix.Helpers module where you need it (probably in the view section of your web/web.ex file).

Phoenix uses Plug.Parsers with a 8 MB limit by default โ€” this affects Exfile too. To increase it, find Plug.Parsers in MyApp.Endpoint and add the length option:

defmodule MyApp.Endpoint do
  use Phoenix.Endpoint, otp_app: :my_app

  plug Plug.Parsers,
    ...
    length: 25_000_000 # bytes; any value you deem necessary
end

Plug

defmodule MyApp.Router do
  use Plug.Router

  forward "/attachments", to: Exfile.Router
  ...

Ecto Integration

The following example will upload a file to the backend configured as โ€œstoreโ€. If you want to upload files to an alternate backend, please take a look at Exfile.Ecto.File and Exfile.Ecto.FileTemplate for instructions on making a custom Ecto.Type for your needs.

defmodule MyApp.User do
  use Ecto.Schema

  schema "users" do
    field :profile_picture, Exfile.Ecto.File
  end
end
defmodule MyApp.Repo.Migrations.AddProfilePictureToUsers do
  use Ecto.Migration

  def change do
    alter table(:users) do
      add :profile_picture, :string
    end
  end
end

Configuration

In config.exs:

config :exfile, Exfile,
  secret: "secret string to generate the token used to authenticate requests",
  backends: %{
    "store" => configuration for the default persistent store
    "cache" => configuration for an ephemeral store holding temporarily uploaded content
  }

See Exfile.Config for defaults.