Add etcd proxy support

* Enforce a etcd-proxy role to a k8s-cluster group members. This
provides an HA layout for all of the k8s cluster internal clients.
* Proxies to be run on each node in the group as a separate etcd
instances with a readwrite proxy mode and listen the given endpoint,
which is either the access_ip:2379 or the localhost:2379.
* A notion for the 'kube_etcd_multiaccess' is: ignore endpoints and
loadbalancers and use the etcd members IPs as a comma-separated
list. Otherwise, clients shall use the local endpoint provided by a
etcd-proxy instances on each etcd node. A Netwroking plugins always
use that access mode.
* Fix apiserver's etcd servers args to use the etcd_access_endpoint.
* Fix networking plugins flannel/calico to use the etcd_endpoint.
* Fix name env var for non masters to be set as well.
* Fix etcd_client_url was not used anywhere and other etcd_* facts
evaluation was duplicated in a few places.
* Define proxy modes only in the env file, if not a master. Del
an automatic proxy mode decisions for etcd nodes in init/unit scripts.
* Use Wants= instead of Requires= as "This is the recommended way to
hook start-up of one unit to the start-up of another unit"
* Make apiserver/calico Wants= etcd-proxy to keep it always up

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>
Co-authored-by: Matthew Mosesohn <mmosesohn@mirantis.com>

roles/etcd/templates/deb-etcd-proxy-docker.initd.j2

@@ -0,0 +1,117 @@
+#!/bin/sh
+set -a
+
+### BEGIN INIT INFO
+# Provides:   etcd-proxy
+# Required-Start:    $local_fs $network $syslog
+# Required-Stop:
+# Default-Start:     2 3 4 5
+# Default-Stop:      0 1 6
+# Short-Description: etcd-proxy
+# Description:
+#   etcd-proxy is a proxy for etcd: distributed, consistent key-value store for shared configuration and service discovery
+### END INIT INFO
+
+PATH=/sbin:/usr/sbin:/bin/:/usr/bin
+DESC="etcd-proxy"
+NAME=etcd-proxy
+DAEMON={{ docker_bin_dir | default("/usr/bin") }}/docker
+DAEMON_ARGS='--restart=always --env-file=/etc/etcd-proxy.env \
+--net=host \
+--stop-signal=SIGKILL \
+-v /usr/share/ca-certificates/:/etc/ssl/certs:ro \
+--name={{ etcd_proxy_member_name | default("etcd-proxy") }} \
+{{ etcd_image_repo }}:{{ etcd_image_tag }} \
+{% if etcd_after_v3 %}
+{{ etcd_container_bin_dir }}etcd
+{% endif %}'
+
+
+SCRIPTNAME=/etc/init.d/$NAME
+DAEMON_USER=etcd-proxy
+STOP_SCHEDULE="${STOP_SCHEDULE:-QUIT/5/TERM/5/KILL/5}"
+PID=/var/run/etcd-proxy.pid
+
+# Exit if the binary is not present
+[ -x "$DAEMON" ] || exit 0
+
+# Define LSB log_* functions.
+# Depend on lsb-base (>= 3.2-14) to ensure that this file is present
+# and status_of_proc is working.
+. /lib/lsb/init-functions
+
+do_status()
+{
+    status_of_proc -p $PID "$DAEMON" "$NAME" && exit 0 || exit $?
+}
+
+# Function that starts the daemon/service
+#
+do_start()
+{
+    start-stop-daemon --background --start --quiet --make-pidfile --pidfile $PID --user $DAEMON_USER --exec $DAEMON -- \
+        $DAEMON_ARGS \
+        || return 2
+}
+
+#
+# Function that stops the daemon/service
+#
+do_stop()
+{
+    start-stop-daemon --stop --quiet --retry=$STOP_SCHEDULE --pidfile $PID --name $NAME
+    RETVAL="$?"
+
+    sleep 1
+    return "$RETVAL"
+}
+
+
+case "$1" in
+  start)
+        log_daemon_msg "Starting $DESC" "$NAME"
+        do_start
+        case "$?" in
+                0|1) log_end_msg 0 || exit 0 ;;
+                2) log_end_msg 1 || exit 1 ;;
+        esac
+        ;;
+  stop)
+        log_daemon_msg "Stopping $DESC" "$NAME"
+        if do_stop; then
+            log_end_msg 0
+        else
+            log_failure_msg "Can't stop etcd-proxy"
+            log_end_msg 1
+        fi
+        ;;
+  status)
+        if do_status; then
+            log_end_msg 0
+        else
+            log_failure_msg "etcd-proxy is not running"
+            log_end_msg 1
+        fi
+        ;;
+
+  restart|force-reload)
+        log_daemon_msg "Restarting $DESC" "$NAME"
+        if do_stop; then
+            if do_start; then
+                log_end_msg 0
+                exit 0
+            else
+                rc="$?"
+            fi
+        else
+           rc="$?"
+        fi
+        log_failure_msg "Can't restart etcd-proxy"
+        log_end_msg ${rc}
+        ;;
+  *)
+        echo "Usage: $SCRIPTNAME {start|stop|status|restart|force-reload}" >&2
+        exit 3
+        ;;
+esac
+