Using targets for deps in umbrella project

I get the following error:

$ MIX_TARGET=postgres mix deps.get
Resolving Hex dependencies...

Failed to use "phoenix_ecto" (version 4.0.0) because
  apps/admin_web/mix.exs requires ~> 3.0
  apps/admin_web/mix.exs requires ~> 4.0

I was unaware of and haven’t used targets yet, but taking a quick look it appears in your deps() you should use target: instead of plural targets:?

I tried using target: with no success

What version of Elixir are you running? And do you have an example repo online to try and reproduce?

I had a need for this a while ago, but worked around it - so I am kind of blindly making suggestions. I will try to reimplement this afternoon in a project of mine and let you know here what I find.

@cohawk I am using Elixir 1.8.1.

I will create an example repo as soon as possible.

Thank you!

Thanks for the reminder - got kinda busy today

No need to create an example repo - it’s easily enough reproducible.

So the digging around the Mix.target PR commit: Introduce Mix.target (#8443) · elixir-lang/elixir@2e576f6 · GitHub

targets: is the correct syntax (since you can also pass a list targets: [:postgres, :absinthe]). I think before I was looking at some pre-merged code.

Anyways:

$ mix deps.get --target postgres

is the correct syntax to fetch target deps instead of MIX_TARGET=postgres mix deps.get

And with that it does give us a couple warnings:

warning: the dependency :phoenix_ecto is duplicated at the top level, please remove one of them

But it does appear to pull the correct target version:

$ mix deps.tree --target postgres
warning: the dependency :phoenix_ecto is duplicated at the top level, please remove one of them
warning: the dependency :phoenix_ecto is duplicated at the top level, please remove one of them
phx_targets_test
...
└── phoenix_ecto ~> 4.0 (Hex package)
    ├── ecto ~> 2.2 or ~> 3.0 (Hex package)
    ├── phoenix_html ~> 2.9 (Hex package)
    └── plug ~> 1.0 (Hex package)

and then for the mssql target:

$ mix deps.get --target mssql
warning: the dependency :phoenix_ecto is duplicated at the top level, please remove one of them
Resolving Hex dependencies...
Dependency resolution completed:
Unchanged:
    ...
Downgraded:
  phoenix_ecto 4.0.0 => 3.5.0 RETIRED!
    (invalid)
warning: the dependency :phoenix_ecto is duplicated at the top level, please remove one of them
* Updating phoenix_ecto (Hex package)

and then confirm with the target deps.tree:

$ mix deps.tree --target mssql
warning: the dependency :phoenix_ecto is duplicated at the top level, please remove one of them
warning: the dependency :phoenix_ecto is duplicated at the top level, please remove one of them
phx_targets_test
...
└── phoenix_ecto ~> 3.0 (Hex package)
    ├── ecto ~> 3.0 (Hex package)
    ├── phoenix_html ~> 2.9 (Hex package)
    └── plug ~> 1.0 (Hex package)

Then you execute using the MIX_TARGET variable:

$ MIX_TARGET=mssql mix phx.server

and where I thought it would get murky about remembering the version from which target I had last fetched the deps for, it reminds you at compile time:

$ MIX_TARGET=postgres mix phx.server
...
Unchecked dependencies for environment dev:
* phoenix_ecto (Hex package)
  the dependency does not match the requirement "~> 4.0", got "3.5.0"
** (Mix) Can't continue due to errors on dependencies

Good stuff.

@cohawk, I appreciate a lot your support.

Where is what I’ve done..

I added an IO.inspect(Mix.target()) inside each of my deps functions. I have multiple functions because I am working in an umbrella project.

  defp deps() do
    IO.inspect(Mix.target())
    [
      {:phoenix, "~> 1.4.0"},
      {:phoenix_pubsub, "~> 1.1"},
      {:phoenix_ecto, "~> 4.0", targets: :postgres},
      {:phoenix_ecto, "~> 3.0", targets: :mssql},
      {:phoenix_html, "~> 2.11"},
      {:phoenix_live_reload, "~> 1.2", only: :dev},
      {:gettext, "~> 0.11"},
      {:jason, "~> 1.0"},
      {:plug_cowboy, "~> 2.0"},
      {:medik_ecto, in_umbrella: true}
    ]
  end

Running mix deps.get using an environment variable I get

$ MIX_TARGET=postgres mix deps.get
:postgres
:postgres
:postgres
:postgres
:postgres
:postgres
Resolving Hex dependencies...

or

$ MIX_TARGET=mssql mix deps.get
:mssql
:mssql
:mssql
:mssql
:mssql
:mssql
Resolving Hex dependencies...

However when I pass the target as an option

$ mix deps.get --targets postgres
:host
:host
:host
:host
:host
:host
Resolving Hex dependencies...

In any case I always get the same error:

Failed to use "phoenix_ecto" (version 4.0.0) because
  apps/admin_web/mix.exs requires ~> 3.0
  apps/admin_web/mix.exs requires ~> 4.0
  apps/patients_web/mix.exs requires ~> 4.0

** (Mix) Hex dependency resolution failed, change the version requirements of your dependencies or unlock them (by using mix deps.update or mix deps.unlock). If you are unable to resolve the conflicts you can try overriding with {:dependency, "~> 1.0", override: true}

I will test on a non umbrella project over the weekend.

You have targets instead of target - from the CLI you can only setup for a single target.

:host is the default target when you do not set the target flag

You want:

$ mix deps.get --target postgres

$ mix deps.get --target postgres
:host
:host
:host
:host
:host
:host
Resolving Hex dependencies...

$ mix deps.get --target mssql
:host
:host
:host
:host
:host
:host
Resolving Hex dependencies...

Yeah, you might be right that the ‘target’ does not propagate through umbrella apps.

Here is my repo from the tests in the above posts - GitHub - cohawk/phx_targets_test: Introduce `Mix.target` test - https://github.com/elixir-lang/elixir/issues/8063 · GitHub

I can try with an umbrella app sometime this weekend - time permitting.

Cheers