support custom env vars for etcd

roles/etcd/defaults/main.yml

@@ -31,6 +31,12 @@ etcd_election_timeout: "5000"
 
 etcd_metrics: "basic"
 
+## A dictionary of extra environment variables to add to etcd.env, formatted like:
+##  etcd_extra_vars:
+##    ETCD_VAR1: "value1"
+##    ETCD_VAR2: "value2"
+etcd_extra_vars: {}
+
 # Limits
 # Limit memory only if <4GB memory on host. 0=unlimited
 etcd_memory_limit: "{% if ansible_memtotal_mb < 4096 %}512M{% else %}0{% endif %}"

roles/etcd/templates/etcd.env.j2

@@ -27,3 +27,7 @@ ETCD_PEER_TRUSTED_CA_FILE={{ etcd_cert_dir }}/ca.pem
 ETCD_PEER_CERT_FILE={{ etcd_cert_dir }}/member-{{ inventory_hostname }}.pem
 ETCD_PEER_KEY_FILE={{ etcd_cert_dir }}/member-{{ inventory_hostname }}-key.pem
 ETCD_PEER_CLIENT_CERT_AUTH={{ etcd_peer_client_auth }}
+
+{% for key, value in etcd_extra_vars.iteritems() %}
+{{ key }}={{ value }}
+{% endfor %}