Add optional deployment mode for Docker etcd_deployment_type

Running etcd in Docker reduces the number of individual file
downloads and services running on the host.

Note: etcd container v3.0.1 moves bindir to /usr/local/bin

Fixes: #298

roles/etcd/tasks/configure.yml

@@ -12,7 +12,7 @@
 
 - name: Configure | Copy etcd.service systemd file
   template:
-    src: etcd.service.j2
+    src: "etcd-{{ etcd_deployment_type }}.service.j2"
     dest: /etc/systemd/system/etcd.service
     backup: yes
   when: ansible_service_mgr == "systemd"
@@ -20,7 +20,7 @@
 
 - name: Configure | Write etcd initd script
   template:
-    src: deb-etcd.initd.j2
+    src: "deb-etcd-{{ etcd_deployment_type }}.initd.j2"
     dest: /etc/init.d/etcd
     owner: root
     mode: 0755

roles/etcd/tasks/install.yml

@@ -1,9 +1,38 @@
 ---
-- name: Install | Copy etcd binary
+- name: Install | Copy etcd binary from downloaddir
   command: rsync -piu "{{ etcd_bin_dir }}/etcd" "{{ bin_dir }}/etcd"
+  when: etcd_deployment_type == "host"
   register: etcd_copy
+
+- name: Install | Copy etcdctl binary from downloaddir
+  command: rsync -piu "{{ etcd_bin_dir }}/etcdctl" "{{ bin_dir }}/etcdctl"
+  when: etcd_deployment_type == "host"
   changed_when: false
 
-- name: Install | Copy etcdctl binary
-  command: rsync -piu "{{ etcd_bin_dir }}/etcdctl" "{{ bin_dir }}/etcdctl"
+#Plan A: no docker-py deps
+- name: Install | Copy etcdctl binary from container
+  command: sh -c "/usr/bin/docker rm -f etcdctl-binarycopy;
+           /usr/bin/docker create --name etcdctl-binarycopy {{ etcd_image_repo }}:{{ etcd_image_tag }} &&
+           /usr/bin/docker cp etcdctl-binarycopy:{{ etcd_container_bin_dir }}etcdctl {{ bin_dir }}/etcdctl &&
+           /usr/bin/docker rm -f etcdctl-binarycopy"
+  when: etcd_deployment_type == "docker"
   changed_when: false
+
+#Plan B: looks nicer, but requires docker-py on all hosts:
+#- name: Install | Set up etcd-binarycopy container
+#  docker:
+#    name: etcd-binarycopy
+#    state: present
+#    image: "{{ etcd_image_repo }}:{{ etcd_image_tag }}"
+#  when: etcd_deployment_type == "docker"
+#
+#- name: Install | Copy etcdctl from etcd-binarycopy container
+#  command: /usr/bin/docker cp "etcd-binarycopy:{{ etcd_container_bin_dir }}etcdctl" "{{ bin_dir }}/etcdctl"
+#  when: etcd_deployment_type == "docker"
+#
+#- name: Install | Clean up etcd-binarycopy container
+#  docker:
+#    name: etcd-binarycopy
+#    state: absent
+#    image: "{{ etcd_image_repo }}:{{ etcd_image_tag }}"
+#  when: etcd_deployment_type == "docker"

roles/etcd/tasks/main.yml

@@ -8,7 +8,7 @@
 - name: Restart etcd if binary changed
   command: /bin/true
   notify: restart etcd
-  when: etcd_copy.stdout_lines
+  when: etcd_deployment_type == "host" and etcd_copy.stdout_lines
 
 # Reload systemd before starting service
 - meta: flush_handlers

roles/etcd/tasks/set_facts.yml

@@ -14,3 +14,7 @@
       {% endfor %}
 - set_fact:
     is_etcd_master: "{{ inventory_hostname in groups['etcd'] }}"
+- set_fact:
+    etcd_after_v3: etcd_version | version_compare("v3.0.0", ">=")
+- set_fact:
+    etcd_container_bin_dir: "{% if etcd_after_v3 %}/usr/local/bin/{% else %}/{% endif %}"