fix the tests, and update documentation

.github/workflows/gcloud.yml

@@ -27,10 +27,10 @@ jobs:
             command: /usr/sbin/init
           - distro: centos:8
             command: /usr/sbin/init
-          - distro: ubuntu:16.04
-            command: /sbin/init
           - distro: ubuntu:18.04
             command: /lib/systemd/systemd
+          - distro: ubuntu:20.04
+            command: /lib/systemd/systemd
           - distro: debian:9
             command: /lib/systemd/systemd
         collection_role:
@@ -48,9 +48,18 @@ jobs:
 
       - name: Install dependencies
         run: |
-          sudo apt install docker
+          sudo apt-get install -y apt-transport-https ca-certificates curl gnupg \
+            lsb-release
+          curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg \
+            --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
+          echo \
+            "deb [arch=amd64 signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu \
+            $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
+          sudo apt-get update
+          sudo apt-get install -y docker-ce docker-ce-cli containerd.io
           python -m pip install --upgrade pip
-          pip install molecule yamllint ansible-lint docker
+          pip install molecule yamllint ansible ansible-lint docker \
+            molecule[docker]
 
       - name: Run role test
         run: >-