# Installing CORS in Elixir-Phoenix Application

While developing API in any framework, we often come across error related to `CORS`. This post will help you fixing `CORS` issue in `Elixir-Phoenix` application.

Suppose, you have an Ember(or any Frontend SPA) application that runs on port `4200` and our Phoenix API is running on port `4000`. When the Ember app tries to consume this API.  It faces error related to `cross-origin` because it is not of the same domain.

`cors_plug` is a plugin available on hex.pm that helps us to deal with this problem. We will quickly create an application and configure `cors_plug` to see it in action.

### Configuring `cors_plug`
- Create a phoenix app `mix phx.new --no-webpack --no-html my_blog_api`. 
- Run `mix ecto.create` to run the migration.
- Now go to `mix.exs` file and add dependency. `{:cors_plug, "~> 2.0"},`. 
- Install dependency by running `mix deps.get`.

- To configure `cors` we need to add it in our plug pipeline.
- For that go to `endpoint.ex` file. In the file right below `plug MyBlogApiWeb.Router` add this line `plug CORSPlug, origin:"*"`. The option `origin` means, what origin we should allow traffic from.
- Adding "*" means we are allowing traffic from everywhere. If we want to be specific for our ember application. We can add `origin: "localhost:4200"`.

Now you can add any endpoint in this phoenix application and test it out in the SPA of your choice. You won't be getting this error.

I hope you like this small post. If you any questions please add the comment below.👇