LiteRT-LM / python /litert_lm_cli /venv_manager.py
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# Copyright 2026 The ODML Authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Virtual environment manager for LiteRT-LM."""
import os
import shutil
import subprocess
import sys
import click
class VenvManager:
"""Manages the virtual environment paths and binaries."""
def __init__(self, prefer_current_venv: bool = False):
self._self_managed_venv_dir = os.path.expanduser("~/.litert-lm/.venv")
if not prefer_current_venv:
self.venv_dir = self._self_managed_venv_dir
else:
self.venv_dir = os.environ.get(
"VIRTUAL_ENV",
sys.prefix
if sys.prefix != sys.base_prefix
else self._self_managed_venv_dir,
)
self.python_bin = os.path.join(self.venv_dir, "bin", "python")
self.pip_bin = os.path.join(self.venv_dir, "bin", "pip")
self.litert_torch_bin = os.path.join(self.venv_dir, "bin", "litert-torch")
self.uv_bin = os.path.join(self.venv_dir, "bin", "uv")
def ensure_venv(self):
"""Ensures that the virtual environment directory exists."""
if os.path.exists(self.venv_dir):
return
if self.venv_dir != self._self_managed_venv_dir:
# Note this should never happen.
raise RuntimeError(
f"Virtual environment directory not found: {self.venv_dir}"
)
click.echo(
click.style(
f"Creating virtual environment in {self.venv_dir}...", fg="cyan"
)
)
os.makedirs(os.path.dirname(self.venv_dir), exist_ok=True)
python_exe = sys.executable or "python3"
subprocess.run([python_exe, "-m", "venv", self.venv_dir], check=True)
def recreate_venv_if_self_managed(self):
"""Deletes and re-creates the virtual environment if it is self-managed.
This ensures we are using the latest litert-torch-nightly. Since uv has
local cache, if the version has been downloaded before, it will be very
fast.
"""
if self.venv_dir != self._self_managed_venv_dir:
# Only recreate if it's the default venv managed by the CLI.
return
if os.path.exists(self.venv_dir):
click.echo(
click.style(
f"Deleting virtual environment in {self.venv_dir}...", fg="cyan"
)
)
shutil.rmtree(self.venv_dir)
self.ensure_venv()
def ensure_binary(self, binary_path):
"""Ensures the binary exists, or installs it if using the default venv."""
if os.path.exists(binary_path):
return
self.ensure_venv()
if binary_path == self.pip_bin:
click.echo(click.style("Ensuring pip is installed...", fg="cyan"))
subprocess.run(
[
self.python_bin,
"-m",
"ensurepip",
"--default-pip",
],
check=True,
)
elif binary_path == self.uv_bin:
self.ensure_binary(self.pip_bin)
click.echo(
click.style(
"Installing uv into the virtual environment...", fg="cyan"
)
)
subprocess.run(
[
self.pip_bin,
"install",
"uv",
"-i",
"https://pypi.org/simple",
],
check=True,
)
elif binary_path == self.litert_torch_bin:
self.ensure_binary(self.uv_bin)
click.echo(click.style("Installing litert-torch with uv...", fg="cyan"))
subprocess.run(
[
self.uv_bin,
"pip",
"install",
"-i",
"https://pypi.org/simple",
"litert-torch-nightly",
"--python",
self.python_bin,
],
check=True,
)