Hi, I wish to configure settings using env variable in like django like so: settings.py

from decouple import config
DEBUG = config('DEBUG') == 'True'

I get this exception:

decouple.UndefinedValueError: DEBUG not found. Declare it as envvar or define a default value.

I have added .env file as prescribed by this library with content

DEBUG=True

Pants is hermetic by default and, towards that end, filters out almost all environment variables by default. You'll need to tell Pants to expose

DEBUG

. I'm going to assume you hit this error in tests, but if not and its during run? You'll need to provide your Pants version to debug further. Continuing with the tests assumption: If you just need the env var for tests in some

python_tests

targets, you can use: https://www.pantsbuild.org/docs/reference-python_tests#codeextra_env_varscode If you need the env var exposed for all tests use: https://www.pantsbuild.org/docs/reference-test#section-extra-env-vars

Yeah pants version is 2.12.0 And I not using for test.. but general env var which includes both settings and secrets.

What Pants goal gives you the failure? Is it

run

?

./pants run projects/appsflyer/:manage -- runserver --noreload

Ok, run - thanks. This may be fixed in newer Pants versions - looking...

It is this - https://pypi.org/project/python-decouple/

Ok - just a sec...

Yeah mechanism for a .env that cuz the following command works:

./pants --subprocess-environment-env-vars="['DEBUG=True']" run projects/appsflyer/:manage -- runserver --noreload

This works for me on 2.12.x. The key was adding a

resource

target for the

.env

file and manually adding that as a requirement of the

pex_binary

target: Setup (the resolve complexity is ignorable but needed to get a self-contained demo working sanely):

$ cat BUILD.foo
python_requirement(
    name="decouple",
    requirements=[
        "python-decouple",
    ],
    modules=["decouple"],
    resolve="foo",
)
python_source(
    name="foo",
    source="foo.py",
    resolve="foo",
)
resource(
    name=".env",
    source=".env",
)
pex_binary(
    name="foo-bin",
    entry_point="foo",
    dependencies=[
        ":.env",
    ],
    resolve="foo",
)
$ cat .env 
DEBUG=bar
$ cat foo.py 
import os
from decouple import config

print(f"CWD: {os.getcwd()}")
print(config("DEBUG", "<>"))

Pants run:

$ ./pants --python-resolves="+{'foo':'foo.lock'}" run :foo-bin
CWD: /home/jsirois/dev/pantsbuild/pants
bar

I got it work for now. By adding a new python source (not a file source) and adding that as a dependency for manage target.

python_sources()

python_source(
    name="env",
    source=".env"
)

pex_binary(
    name="manage",
    entry_point="manage.py",
    dependencies=[
        "./appsflyer:appsflyer",
        ":env"
    ],
    restartable=True
)

Though I am not very sure how this worked, but it did.

Yeah, that's why I used

resource

- `python_source`works too. There is currently oddness where PEXes built by Pants cannot depend on

file

targets even though Pex the tool accepts plain old files just fine. So you have to lie and call the file a

resource

or

python_source

.

Yeah resource worked too. Thanks John.