Managing dependencies #
Dependency groups #
Poetry provides a way to organize your dependencies by groups. For instance, you might have dependencies that are only needed to test your project or to build the documentation.
To declare a new dependency group, use a
<group> is the name of your dependency group (for instance,
[tool.poetry.group.test] # This part can be left out [tool.poetry.group.test.dependencies] pytest = "^6.0.0" pytest-mock = "*"
All dependencies must be compatible with each other across groups since they will be resolved regardless of whether they are required for installation or not (see Installing group dependencies).
Think of dependency groups as labels associated with your dependencies: they don’t have any bearings on whether their dependencies will be resolved and installed by default, they are simply a way to organize the dependencies logically.
The dependencies declared in
tool.poetry.dependencies are part of an implicit
[tool.poetry.dependencies] # main dependency group httpx = "*" pendulum = "*"
[tool.poetry.group.test.dependencies] pytest = "^6.0.0" pytest-mock = "*"
Dependency groups, other than the implicit
main group, must only contain dependencies you need in your development
process. Installing them is only possible by using Poetry.
To declare a set of dependencies, which add additional functionality to the project during runtime,
use extras instead. Extras can be installed by the end user using
A note about the
Any dependency declared in the
dev-dependencies section will automatically be added to a
So the two following notations are equivalent:
[tool.poetry.dev-dependencies] pytest = "^6.0.0" pytest-mock = "*"
[tool.poetry.group.dev.dependencies] pytest = "^6.0.0" pytest-mock = "*"
Poetry will slowly transition away from the
dev-dependencies notation which will soon be deprecated,
so it’s advised to migrate your existing development dependencies to the new
Optional groups #
A dependency group can be declared as optional. This makes sense when you have a group of dependencies that are only required in a particular environment or for a specific purpose.
[tool.poetry.group.docs] optional = true [tool.poetry.group.docs.dependencies] mkdocs = "*"
Optional groups can be installed in addition to the default dependencies by using the
option of the
poetry install --with docs
Adding a dependency to a group #
add command is the preferred way to add dependencies
to a group. This is done by using the
--group (-G) option.
poetry add pytest --group test
If the group does not already exist, it will be created automatically.
Installing group dependencies #
By default, dependencies across all non-optional groups will be installed when executing
maingroup defined in
tool.poetry.dependenciesas well as all groups that are not explicitly marked as an optional group.
You can exclude one or more groups with the
poetry install --without test,docs
You can also opt in optional groups by using the
poetry install --with docs
When used together,
--without takes precedence over
--with. For example, the following command
will only install the dependencies specified in the optional
poetry install --with test,docs --without docs
Finally, in some case you might want to install only specific groups of dependencies
without installing the default set of dependencies. For that purpose, you can use
poetry install --only docs
If you only want to install the project’s runtime dependencies, you can do so with the
--only main notation:
poetry install --only main
If you want to install the project root, and no other dependencies, you can use
poetry install --only-root
Removing dependencies from a group #
remove command supports a
to remove packages from a specific group:
poetry remove mkdocs --group docs
Synchronizing dependencies #
Poetry supports what’s called dependency synchronization. Dependency synchronization ensures
that the locked dependencies in the
poetry.lock file are the only ones present
in the environment, removing anything that’s not necessary.
This is done by using the
--sync option of the
poetry install --sync
--sync option can be combined with any dependency groups related options
to synchronize the environment with specific groups. Note that extras are separate. Any
extras not selected for install are always removed, regardless of
poetry install --without dev --sync poetry install --with docs --sync poetry install --only dev
--syncoption replaces the
--remove-untrackedoption which is now deprecated.
Layering optional groups #
When you omit the
--sync option, you can install any subset of optional groups without removing
those that are already installed. This is very useful, for example, in multi-stage
Docker builds, where you run
poetry install multiple times in different build stages.