add etc tunning options

https://coreos.com/etcd/docs/latest/tuning.html

etcd_snapshot_count
and
ionice priority

roles/etcd/templates/etcd-events.env.j2

@@ -13,6 +13,9 @@ ETCD_NAME={{ etcd_member_name }}-events
 ETCD_PROXY=off
 ETCD_INITIAL_CLUSTER={{ etcd_events_peer_addresses }}
 ETCD_AUTO_COMPACTION_RETENTION={{ etcd_compaction_retention }}
+{% if etcd_snapshot_count is defined %}
+ETCD_SNAPSHOT_COUNT={{ etcd_snapshot_count }}
+{% endif %}
 
 # TLS settings
 ETCD_TRUSTED_CA_FILE={{ etcd_cert_dir }}/ca.pem

roles/etcd/templates/etcd.env.j2

@@ -13,6 +13,9 @@ ETCD_NAME={{ etcd_member_name }}
 ETCD_PROXY=off
 ETCD_INITIAL_CLUSTER={{ etcd_peer_addresses }}
 ETCD_AUTO_COMPACTION_RETENTION={{ etcd_compaction_retention }}
+{% if etcd_snapshot_count is defined %}
+ETCD_SNAPSHOT_COUNT={{ etcd_snapshot_count }}
+{% endif %}
 
 # TLS settings
 ETCD_TRUSTED_CA_FILE={{ etcd_cert_dir }}/ca.pem

roles/etcd/templates/etcd.j2

@@ -6,16 +6,19 @@
   -v /etc/ssl/certs:/etc/ssl/certs:ro \
   -v {{ etcd_cert_dir }}:{{ etcd_cert_dir }}:ro \
   -v {{ etcd_data_dir }}:{{ etcd_data_dir }}:rw \
-  {% if etcd_memory_limit is defined %}
+{% if etcd_memory_limit is defined %}
   --memory={{ etcd_memory_limit|regex_replace('Mi', 'M') }} \
-  {% endif %}
-  {% if etcd_cpu_limit is defined %}
+{% endif %}
+{% if etcd_cpu_limit is defined %}
   --cpu-shares={{ etcd_cpu_limit|regex_replace('m', '') }} \
-  {% endif %}
-  {% if etcd_blkio_weight is defined %}
+{% endif %}
+{% if etcd_blkio_weight is defined %}
   --blkio-weight={{ etcd_blkio_weight }} \
-  {% endif %}
+{% endif %}
   --name={{ etcd_member_name | default("etcd") }} \
   {{ etcd_image_repo }}:{{ etcd_image_tag }} \
+{% if etcd_ionice is defined %}
+  /bin/ionice {{ etcd_ionice }} \
+{% endif %}
   /usr/local/bin/etcd \
   "$@"