Tailwind

Mix tasks for installing and invoking tailwindcss via the stand-alone tailwindcss cli

Installation

If you are going to build assets in production, then you add tailwind as dependency on all environments but only start it in dev:

def deps do
  [
    {:tailwind, "~> 0.3", runtime: Mix.env() == :dev}
  ]
end

Once installed, change your config/config.exs to pick your Tailwind version of choice:

config :tailwind, version: "4.1.12"

Note that :tailwind 0.3+ assumes Tailwind v4+ by default. It still supports Tailwind v3, but some configuration options when setting up a new project might be different. If you use Tailwind v3, also have a look at the README in the 0.2 branch.

Now you can install Tailwind by running:

$ mix tailwind.install

or if your platform isn't officially supported by Tailwind, you can supply a third party path to the binary the installer wants (beware that we cannot guarantee the compatibility of any third party executable):

$ mix tailwind.install https://people.freebsd.org/~dch/pub/tailwind/v3.2.6/tailwindcss-freebsd-x64

And invoke Tailwind with:

$ mix tailwind default

The executable is kept at _build/tailwind-TARGET. Where TARGET is your system target architecture.

Profiles

The first argument to tailwind is the execution profile. You can define multiple execution profiles with the current directory, the OS environment, and default arguments to the tailwind task in your config/config.exs:

config :tailwind,
  version: "4.1.12",
  default: [
    args: ~w(
      --input=assets/css/app.css
      --output=priv/static/assets/css/app.css
    ),
    cd: Path.expand("..", __DIR__)
  ]

When mix tailwind default is invoked, the task arguments will be appended to the ones configured above.

Adding to Phoenix

Note that applications generated with Phoenix older than 1.8 still use Tailwind v3 by default. If you're using Tailwind v3 please refer to the README in the v0.2 branch instead.

To add Tailwind v4 to an application using Phoenix, first add this package as a dependency in your mix.exs:

def deps do
  [
    {:phoenix, "~> 1.8"},
    {:tailwind, "~> 0.3", runtime: Mix.env() == :dev}
  ]
end

Also, in mix.exs, add tailwind to the assets.deploy alias for deployments (with the --minify option):

"assets.deploy": ["tailwind default --minify", ..., "phx.digest"]

Now let's change config/config.exs to tell tailwind to build our css bundle into priv/static/assets/css. We'll also give it our assets/css/app.css as our css entry point:

config :tailwind,
  version: "4.1.12",
  default: [
    args: ~w(
      --input=assets/css/app.css
      --output=priv/static/assets/css/app.css
    ),
    cd: Path.expand("..", __DIR__)
  ]

Make sure the "assets" directory from priv/static is listed in the :only option for Plug.Static in your lib/my_app_web/endpoint.ex

If your Phoenix application is using an umbrella structure, you should specify the web application's asset directory in the configuration:

config :tailwind,
  version: "4.1.12",
  default: [
    args: ...,
    cd: Path.expand("../apps/<folder_ending_with_web>", __DIR__)
  ]

For development, we want to enable watch mode. So find the watchers configuration in your config/dev.exs and add:

  tailwind: {Tailwind, :install_and_run, [:default, ~w(--watch)]}

Note we are enabling the file system watcher.

Finally, create the relevant assets/css/app.css file:

@import "tailwindcss" source(none);
@source "../css";
@source "../js";
@source "../../lib/YOUR_APP_web";

@custom-variant phx-click-loading (.phx-click-loading&, .phx-click-loading &);
@custom-variant phx-submit-loading (.phx-submit-loading&, .phx-submit-loading &);
@custom-variant phx-change-loading (.phx-change-loading&, .phx-change-loading &);

We also strongly recommend setting up the @source paths in your in app.css file to watch assets/css, assets/js and lib/YOUR_APP_web, as above. Without those, too many files (including build artifacts) may be watched, leading to frequent recompilations.

Updating from Tailwind v3 to v4

For a typical Phoenix application, updating from Tailwind v3 to v4 requires the following steps:

1. Update the :tailwind library to version 0.3+

    defp deps do
      [
   -    {:tailwind, "~> 0.2", runtime: Mix.env() == :dev},
   +    {:tailwind, "~> 0.3", runtime: Mix.env() == :dev},
      ]
    end

2. Adjust the configuration to run Tailwind from the root of your repo (or the web app in an umbrella project):

    config :tailwind,
   -   version: "3.4.13",
   +   version: "4.1.12",
       default: [
         args: ~w(
   -       --config=tailwind.config.js
   -       --input=css/app.css
   -       --output=../priv/static/assets/app.css
   +       --input=assets/css/app.css
   +       --output=priv/static/assets/css/app.css
        ),
   -    cd: Path.expand("../assets", __DIR__)
   +    cd: Path.expand("..", __DIR__)
     ]

   This allows Tailwind to automatically pick up classes from your project. Tailwind v4 does not require explicit configuration of sources.

3. Adjust the Tailwind imports in your app.css

   -@import "tailwindcss/base";
   -@import "tailwindcss/components";
   -@import "tailwindcss/utilities";
   +@import "tailwindcss";

4. Follow the Tailwind v4 upgrade guide to address deprecations.

5. Optional: remove the tailwind.config.js and switch to the new CSS based configuration. For more information, see the previously mentioned upgrade guide and the documentation on functions and directives.

License

Copyright (c) 2022 Chris McCord. Copyright (c) 2021 Wojtek Mach, José Valim.

tailwind source code is licensed under the MIT License.