Add support for atomic host

Updates based on feedback

Simplify checks for file exists

remove invalid char

Review feedback. Use regular systemd file.

Add template for docker systemd atomic

roles/docker/templates/docker-dns.conf.j2

@@ -3,4 +3,4 @@ Environment="DOCKER_DNS_OPTIONS=\
     {% for d in docker_dns_servers %}--dns {{ d }} {% endfor %} \
     {% for d in docker_dns_search_domains %}--dns-search {{ d }} {% endfor %} \
     {% for o in docker_dns_options %}--dns-opt {{ o }} {% endfor %} \
-"
+"

roles/docker/templates/docker-options.conf.j2

@@ -1,2 +1,2 @@
 [Service]
-Environment="DOCKER_OPTS={% if docker_options is defined %}{{ docker_options }}{% endif %}"
+Environment="DOCKER_OPTS={% if docker_options is defined %}{{ docker_options }}{% endif %}"

roles/docker/templates/docker_atomic.service.j2

@@ -0,0 +1,38 @@
+[Unit]
+Description=Docker Application Container Engine
+Documentation=http://docs.docker.com
+After=network.target
+Wants=docker-storage-setup.service
+
+[Service]
+Type=notify
+NotifyAccess=all
+EnvironmentFile=-/etc/sysconfig/docker
+EnvironmentFile=-/etc/sysconfig/docker-storage
+EnvironmentFile=-/etc/sysconfig/docker-network
+Environment=GOTRACEBACK=crash
+Environment=DOCKER_HTTP_HOST_COMPAT=1
+Environment=PATH=/usr/libexec/docker:/usr/bin:/usr/sbin
+ExecReload=/bin/kill -s HUP $MAINPID
+Delegate=yes
+KillMode=process
+ExecStart=/usr/bin/dockerd-current \
+          --add-runtime docker-runc=/usr/libexec/docker/docker-runc-current \
+          --default-runtime=docker-runc \
+          --exec-opt native.cgroupdriver=systemd \
+          --userland-proxy-path=/usr/libexec/docker/docker-proxy-current \
+          $DOCKER_OPTS \
+          $DOCKER_STORAGE_OPTIONS \
+          $DOCKER_NETWORK_OPTIONS \
+          $DOCKER_DNS_OPTIONS \
+          $ADD_REGISTRY \
+          $BLOCK_REGISTRY \
+          $INSECURE_REGISTRY
+LimitNOFILE=1048576
+LimitNPROC=1048576
+LimitCORE=infinity
+TimeoutStartSec=1min
+Restart=on-abnormal
+
+[Install]
+WantedBy=multi-user.target