Cirrus CLI is a tool for running containerized tasks reproducibly in any environment. Most commonly, Cirrus tasks are used as part of continuous integration workflows but can also be used as part of local development process as a hermetic replacement of helper scripts/Makefiles. Cirrus CLI runs your tasks locally the same way they are executed in CI or on your colleague’s machine. Immutability of containers ensures the tasks will be executed the same way years from now regardless what versions of packages you’ll have locally.