Skip to main content

Environment Variable Context Manager

Project description


pypi Build Status codecov Code Style

Manage environment variables in a temporary scope.

Some products use environment variables as a primary means to supply credentials. To ensure the lifetime of exposed credentials is short, wrap them in a TemporaryEnvironment so that they are automatically destroyed on scope exit.

You can:

  • Set or unset environment variables inside a with code block,
  • Get a warning if the code block modifies one of the environment variables,
  • Optionally bypass restoration of the original environment variable value if the code block modifies the environment variable.


Install the latest version of tempenv:

pip install tempenv


Each of these examples can be found in the tests.

Set some environment variables temporarily: (see tests/

def test_set(self):
    user_before = os.environ.get("USER")
    with TemporaryEnvironment({"USER": "nobody", "OTHER": "foo"}):
        assert os.environ.get("USER") == "nobody"
        assert os.environ.get("OTHER") == "foo"
    assert os.environ.get("USER") == user_before

Changing the value to None will unset the environment variable during the code block (see tests/

def test_unset(self):
    os.environ["DEBUG"] = "1"
    with TemporaryEnvironment({"DEBUG": None}):
        assert "DEBUG" not in os.environ
    assert "DEBUG" in os.environ

Changing a temporary environment variable during the scope will cause a warning (see tests/

def test_overwritten_in_context(self):
    with self.assertWarnsRegex(EnvironmentVariableChangedWarning, "FOO"):
        with TemporaryEnvironment({"FOO": "BAR"}):
            os.environ["FOO"] = "SAM"

If you set the optional argument restore_if_changed=False then a change during the scope of the TemporaryEnvironment will not issue a warning and will not restore to the original value (see tests/

def test_ignored_overwrite_in_context(self):
    os.environ["FOO"] = "BAR"
    with TemporaryEnvironment({"FOO": "SAM"}, restore_if_changed=False):
        os.environ["FOO"] = "DEAN"
    assert os.environ["FOO"] == "DEAN"

You can use TemporaryEnvironment in a unittest scope as follows (see tests/

@TemporaryEnvironment({"USER": "Crowley"})
def test_check(self):
    assert os.environ.get("USER") == "Crowley"


Released under the Apache Software License, Version 2.0 (see LICENSE):

   Copyright (C) 2019 - 2022 James E. King III (@jeking3) <>


Please report any bugs that you find on GitHub. Or, even better, fork the repository on GitHub and create a pull request (PR). We welcome all changes, big or small, and we will help you make the PR if you are new to git (just ask on the issue and/or see CONTRIBUTING.rst).

Project details

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

tempenv-2.0.0.tar.gz (10.0 kB view hashes)

Uploaded source

Built Distribution

tempenv-2.0.0-py3-none-any.whl (9.4 kB view hashes)

Uploaded py3

Supported by

AWS AWS Cloud computing Datadog Datadog Monitoring Facebook / Instagram Facebook / Instagram PSF Sponsor Fastly Fastly CDN Google Google Object Storage and Download Analytics Huawei Huawei PSF Sponsor Microsoft Microsoft PSF Sponsor NVIDIA NVIDIA PSF Sponsor Pingdom Pingdom Monitoring Salesforce Salesforce PSF Sponsor Sentry Sentry Error logging StatusPage StatusPage Status page