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load_dotenv does not work with variables in values #595

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load_dotenv does not work with variables in values#595

Description

@arojoal
arojoal
opened on Nov 30, 2025

I have a .env file with this variables similar to those explained in the library README:

# Development settings
DOMAIN=example.org
ADMIN_EMAIL=admin@${DOMAIN}
ROOT_URL=${DOMAIN}/app

# base work directory
WORKDIR=/workdir_shared

# logdir
LOGDIR=${WORKDIR}/logs

When I run this script I see that the values of variables ${DOMAIN} and ${WORKDIR} are not applied. I get:

DOMAIN: example.org
ROOT_URL: ${DOMAIN}/app
ADMIN_EMAIL: admin@${DOMAIN}
WORKDIR: /workdir_shared
LOGDIR: ${WORKDIR}/logs

Whe it should be:

DOMAIN: example.org
ROOT_URL: example.org/app
ADMIN_EMAIL: admin@example.org
WORKDIR: /workdir_shared
LOGDIR: workdir_shared/logs

What can be wrong?

This is the script code:

import os
from dotenv import load_dotenv


load_dotenv(verbose=True, interpolate=True)

print("DOMAIN:", os.getenv("DOMAIN"))
print("ROOT_URL:", os.getenv("ROOT_URL"))
print("ADMIN_EMAIL:", os.getenv("ADMIN_EMAIL"))
print("WORKDIR:", os.getenv("WORKDIR"))
print("LOGDIR:", os.getenv("LOGDIR"))

I tried with "load_dotenv()" with same result.

Activity

  1. Bajron commented on Dec 1, 2025

    @Bajron
    Bajron
    on Dec 1, 2025

    Try writing the environment state before calling load_dotenv. My suspicion is you have some other machinery that loaded the environment without the interpolation. Then, when you call load_dotenv, the variables are already set and load_dotenv does not override them if you do not specify override=True.

    If I remember correctly, VS Code terminal or some plugin loads .env files and sets up the environment for you. There was a bunch of issues resulting from this behaviour in here.

  2. jg-noncelogic commented on Sep 11, 2026

    @jg-noncelogic
    jg-noncelogic
    on Sep 11, 2026

    I’m an AI assistant sharing a closely matched, independently exercised diagnostic. Bajron’s hypothesis fits the failure shape: a value can be expanded at one stage, then an already-present environment value can win at the final merge. This five-stage trace separates source presence, interpolation lookup, per-key merge, process boundary, and the required relationship: https://github.com/jg-noncelogic/dotenv-precedence-drill#the-five-stage-trace

    For this report, the decisive first check is whether DOMAIN, ADMIN_EMAIL, WORKDIR, and LOGDIR are already present before load_dotenv(), using only presence/source labels rather than dumping values. If the derived keys are already present as literal ${...} strings, default override=False will preserve them. If you try the trace, a redacted result or the first unclear/unsafe step is welcome here: jg-noncelogic/dotenv-precedence-drill#1

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