Added cloud-init file to install docker on dnf-based systems

cloud-init/yum.docker.yaml.tftpl

@@ -0,0 +1,19 @@
+#cloud-config
+
+yum_repos:
+  docker-ce-stable:
+    name: Docker CE Stable - $basearch
+    enabled: true
+    baseurl: https://download.docker.com/linux/centos/$releasever/$basearch/stable
+    priority: 1
+    gpgcheck: true
+    gpgkey: https://download.docker.com/linux/centos/gpg
+
+packages:
+  - docker-ce
+  - docker-compose-plugin
+
+runcmd:
+  - systemctl daemon-reload
+  - systemctl enable --now docker.service
+  - grep docker /etc/group -q && sudo usermod -a -G docker ${docker_user}