Add a "setup:" setting to allow running setup scripts before any command?

[jooola]

I'm looking for a tool that can run source venv/bin/activate and run the commands in that same shell. It is not cleanly doable using make, and so I tried Task.

It appears we can't do this using Task. Is there a way to have a workaround or add an option to run all commands in the same shell ?

[andreynering]

Hi @jooola,

Can you explain more why you think this'd be useful? Perhaps an example...

[jooola]

When developing a Python project within a Virtual environment with all its dependencies, we always need to activate this virtual environment in order to run project tasks like testing, linting, building.

To set up the environment by hand, we run the following commands (where requirements.txt lists all the dependencies):

python3 -m venv venv
source venv/bin/activate
pip -q install --upgrade -r requirements.txt

Since the source command is altering the shell to activate it, we need to stay in it to execute the next commands. So I suggested to allow to run all the commands within the same shell.

The option should also all to run all the dependencies in the same shell.

Sorry for my previous message, I clearly wasn't describing my problem enough.

[smyrman]

You can do this today as a multi-line command, but you need to somehow duplicate the setup of venv to each command, e.g. as a template variable, or just copy-paste, which ever is easier.

[jooola]

It would be something like this I guess ?

vars:
  VENV: |-
    test -d venv || python3 -m venv venv
    source venv/bin/activate


tasks:
  setup:
    cmds:
      - |
        {{.VENV}}
        pip -q install --upgrade -r requirements.txt

But dependencies inheritance cannot work in this case, that was the point of chaining dependencies. But this work around could work, I'll try it out. Thanks

[smyrman]

👍

Remember to also add a set -e on of multi-line commands to ensure they exit on error.

vars:
  VENV: |-
    test -d venv || python3 -m venv venv
    source venv/bin/activate


tasks:
  setup:
    cmds:
    - |
      set -e
      {{.VENV}}
      pip -q install --upgrade -r requirements.txt

[smyrman]

But dependencies inheritance cannot work in this case, that was the point of chaining dependencies.

No it can't. Dependencies, or any other cmd, can never change the environment in task, which is what would be needed for that to work. The environment now, is evaluated/generated from scratch every-time before a task is run.

At an early stage of task, there was a "set" property, that could set the environment to the output of a command, but it was deprecated with good reason.

[andreynering]

As @smyrman said, multi-line strings should solve this use case. The downside is that you have to concat the setup stage in each needed command.

Maybe we could add a setup flag to task/global to setup stuff before all commands?

version: '2'

setup:
  - set -e
  - rbenv init

tasks:
  # ...

Sharing state between command calls for a single task would be possible, but it'd be likely confusing.

[stephencheng]

@andreynering https://github.com/direnv/direnv might be considered to achieve this? it actually load the sourced export values into its context. If so, can part of its code incorporated?

[andreynering]

@stephencheng Interesting idea, worth studying the possibility. Thanks for sharing.