[Cherry-pick] fix installation compatibility of ubuntu 20.04 (#5257)

Author: hzy46

contrib/kubespray/environment-check.yml

@@ -1,4 +1,9 @@
 ---
+- hosts: all,localhost
+  gather_facts: false
+  roles:
+    - { role: set-python3 }
+
 - hosts: all
   gather_facts: false
   tasks:

contrib/kubespray/pre-installation.yml

@@ -0,0 +1,11 @@
+---
+- hosts: all,localhost
+  gather_facts: false
+  roles:
+    - { role: set-python3 }
+
+- hosts: all
+  become: true
+  become_user: root
+  roles:
+    - { role: pre-installation }

contrib/kubespray/quick-start-kubespray.sh

@@ -35,5 +35,8 @@ ansible all -i ${HOME}/pai-deploy/cluster-cfg/hosts.yml -m ping || exit $?
 echo "Performing pre-check..."
 ansible-playbook -i ${HOME}/pai-pre-check/pre-check.yml set-host-daemon-port-range.yml -e "@${CLUSTER_CONFIG}" || exit $?
 
+echo "Performing pre-installation..."
+ansible-playbook -i ${HOME}/pai-deploy/cluster-cfg/hosts.yml pre-installation.yml || exit $?
+
 echo "Starting kubernetes..."
 /bin/bash script/kubernetes-boot.sh || exit $?

contrib/kubespray/roles/pre-installation/defaults/main.yml

@@ -0,0 +1,21 @@
+---
+# If sshpass is not installed on target machine, 
+# kubespray 2.11 may have these issues:
+# https://github.com/kubernetes-sigs/kubespray/issues/6906
+# https://github.com/kubernetes-sigs/kubespray/issues/5693
+# This is resolved in PR https://github.com/kubernetes-sigs/kubespray/pull/6907
+- name: "Install sshpass"
+  apt:
+    name: sshpass
+    state: present
+
+
+# workaround for ubuntu 20.04
+# This is resolved in https://github.com/kubernetes-sigs/kubespray/pull/6157
+- name: "Install Python"
+  apt:
+    name: python
+    state: present
+  when:
+  - ansible_distribution_version is version('20.04', '=')
+

contrib/kubespray/roles/pre-installation/tasks/main.yml

@@ -0,0 +1,13 @@
+---
+# Ubuntu 20.04 doesn't have python2 pre-installed,
+# but Ubuntu 16.04, 18.04, and 20.04 all have python3 pre-installed.
+# So we use python3 as the default interpreter.
+# Also, we use `sudo python3` to execute python on dev box machine.
+# It is better to align with it here to prevent `ansible-playbook` from failing into another python.
+- name: set ansible_python_interpreter to python3
+  set_fact:
+    ansible_python_interpreter: "/usr/bin/python3"
+
+- name: output ansible_python_interpreter
+  debug:
+    var: ansible_python_interpreter

contrib/kubespray/roles/set-python3/defaults/main.yml

@@ -40,3 +40,10 @@ sudo apt-get -y install sshpass
 
 echo "Install kubespray's requirements and ansible is included"
 sudo python3 -m pip install -r ${HOME}/pai-deploy/kubespray/requirements.txt
+
+# ansible 2.7 doesn't support distribution info collection on Ubuntu 20.04
+# Use ansible 2.9.7 as a workaround
+# Reference: https://stackoverflow.com/questions/61460151/ansible-not-reporting-distribution-info-on-ubuntu-20-04
+# We can upgrade kubespray version to avoid this issue in the future.
+sudo python3 -m pip install ansible==2.9.7
+

contrib/kubespray/roles/set-python3/tasks/main.yml

@@ -2,7 +2,10 @@
 
 echo "setup k8s cluster"
 cd ${HOME}/pai-deploy/kubespray
-ansible-playbook -i inventory/pai/hosts.yml cluster.yml --become --become-user=root -e "@inventory/pai/openpai.yml" || exit $?
+# Ubuntu 20.04 doesn't have python2 pre-installed,
+# but Ubuntu 16.04, 18.04, and 20.04 all have python3 pre-installed.
+# So we use python3 as the default interpreter.
+ansible-playbook -i inventory/pai/hosts.yml -e "ansible_python_interpreter=/usr/bin/python3" cluster.yml --become --become-user=root -e "@inventory/pai/openpai.yml" || exit $?
 
 sudo mkdir -p ${HOME}/pai-deploy/kube || exit $?
 sudo cp -rf ${HOME}/pai-deploy/kubespray/inventory/pai/artifacts/admin.conf ${HOME}/pai-deploy/kube/config || exit $?

contrib/kubespray/script/environment.sh

@@ -1,4 +1,9 @@
 ---
+- hosts: all,localhost
+  gather_facts: false
+  roles:
+    - { role: set-python3 }
+
 - hosts: gpu
   become: true
   become_user: root