Phoenix code reload in umbrella with multiple app

I have an umbrella project with multiple apps. Two are just libraries with utilities and shared code, while the others are Phoenix applications that can be served.

For instance:

Umbrella app
├── core (shared library)
├── common (shared library)
│   
├── backoffice (phoenix app)
│   depends on
│   ├── common (in umbrella)
│   └── core (in umbrella)
├── frontend_1 (phoenix app)
│   depends on
│   ├── common (in umbrella)
│   └── core (in umbrella)
├── frontend_2 (phoenix app)
│   depends on
│   ├── common (in umbrella)
│   └── core (in umbrella)

During my development process, I need to start one Phoenix app at a time, and I do this with:

mix do --app backoffice cmd mix phx.server

But in this way, if I change something in core or common, the code is not hot reloaded and I need to restart the server for the changes to take effect.

How can I fix this? Can I start the server from the umbrella root but selecting only one app?

Hang on @Gigitsu I have you covered with my own contribution to Phoenix xD.

Check out the :reloadable_apps option that I added to Phoenix a while ago. My use case was similar but not identical, so I am wondering if it will work for you.

https://hexdocs.pm/phoenix/Phoenix.CodeReloader.html#reload/2

config :your_app, Backoffice.Endpoint,
  reloadable_apps: [:frontend_1, :frontend_2, :backoffice, :core, :common]
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Hi @hubertlepicki, thank you.

I’ve tried configuring that option with reloadable_apps: [:common, :core], but it seemed to not work because I was expecting a Rebuilding... message in the console after changing something in the common/core library. I was mistaken; the code appears to be recompiled correctly event without that message.

Do you know why only the main app triggers the Rebuilding... message in the console? Also, should I include the app itself in the reloadable_apps property or can I omit it?

For example, could this configuration be enough

config :backoffice, Backoffice.Endpoint,
  reloadable_apps: [:core, :common]

or do I need to explicitly put :backoffice like below?

config :backoffice, Backoffice.Endpoint,
  reloadable_apps: [:backoffice, :core, :common]

I’ve also added more patterns to the live_reload configuration in this way:

config :backoffice, Backoffice.Endpoint,
  live_reload: [
    patterns: [
      ~r"priv/static/.*(js|css|png|jpeg|jpg|gif|svg)$",
      ~r"priv/gettext/.*(po)$",
      ~r"lib/backoffice/(controllers|live|components)/.*(ex|heex)$"
      
      # core and common patters
      ~r"../core/lib/core/.*/.*(ex|heex)$",
      ~r"../common/lib/common/.*/.*(ex|heex)$"
    ]
  ]

but I don’t know if it’s correct or not.

Thank you for both your answer and your contribution.

Edit:
I’ve noticed that I need to manually reload the page to trigger the compilation of the core/common libs

By adding this extra config and setting the paths on live_reload I was able to get live reload working on my umbrella app perfectly, without any manual action.
Mine looks like:

~r"../mula/lib/.*(ex|heex)$"

Thanks @samaravilha.

I’ve managed to get code reload working by adding the following configurations in my dev.exs file

config :phoenix_live_reload, :dirs, [
  Path.expand("../apps/my_app", __DIR__),
  Path.expand("../apps/common", __DIR__),
  Path.expand("../apps/core", __DIR__)
]
config :my_app, MyApp.Endpoint,
  live_reload: [
    patterns: [
      ~r"../common/lib/common/(\w+/)*.*(ex|heex)$",
      ~r"../core/lib/core/(\w+/)*.*(ex|heex)$",
      ~r"priv/gettext/.*(po)$",
      ~r"priv/static/.*(js|css|png|jpeg|jpg|gif|svg)$",
      ~r"lib/my_app/(controllers|live|components)/.*(ex|heex)$"
    ]
  ]
config :my_app, MyApp.Endpoint,
  ...
  reloadable_apps: [:my_app , :core, :common],
  ...
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