kubespray/requirements.txt

ansible>=2.2.1
netaddr
# Ansible 2.2.1 requires jinja2<2.9, see <https://github.com/ansible/ansible/blob/v2.2.1.0-1/setup.py#L25>,
# but without explicit limiting upper jinja2 version here pip ignores
# Ansible requirements and installs latest available jinja2
# (pip is not very smart here), which is incompatible with with
# Ansible 2.2.1.
# With incompatible jinja2 version "ansible-vault create" (and probably other parts)
# fails with:
#   ERROR! Unexpected Exception: The 'jinja2<2.9' distribution was not found 
#   and is required by ansible
# This upper limit should be removed in 2.2.2 release, see:
# <https://github.com/ansible/ansible/commit/978311bf3f91dae5806ab72b665b0937adce38ad>
jinja2>=2.8,<2.9