poetry install: Install from Lock Command Reference

Install exactly what the lockfile pins.

poetry install reads poetry.lock and installs the resolved dependencies into the project environment. It is the core dependency-restore step in a Poetry-based CI job.

Common flags / usage

poetry install -- install deps plus the project itself
--no-root -- skip installing the project package
--only main -- install only the main dependency group
--with dev -- include an optional group
--sync -- remove packages not in the lock
--no-interaction -- never prompt (CI default)

Example

shell

- uses: actions/setup-python@v5
  with:
    python-version: '3.12'
- run: pipx install poetry
- run: poetry install --with dev --no-interaction

In CI

If pyproject.toml changed without re-locking, poetry install reports the lock is inconsistent -- run poetry lock and commit it. Cache Poetry virtualenvs directory (poetry config virtualenvs.in-project true keeps it at .venv) to speed repeated runs.

Key takeaways

poetry install restores dependencies pinned in poetry.lock.
--no-root and --only/--with control what gets installed.
Always pass --no-interaction in CI to avoid prompts.

Related guides

poetry add: Add a Dependency Command ReferenceReference for poetry add in CI and dev: adding a dependency to pyproject.toml and the lock, group and dry-run… poetry lock: Resolve the Lockfile Command ReferenceReference for poetry lock in CI: resolving dependencies into poetry.lock without installing, the consistency… poetry run: Run in the Project Env Command ReferenceReference for poetry run in CI: executing a command inside the project virtualenv without activating it, comm…