Introduce ad-hoc Erlang cookie configuration for the dev scripts

Extend the `dev/run` and `dev/remsh` scripts in ways that would
let the users to set the cookie for inter-node communication
directly from the command line.  This may come handy in certain
cases, e.g. when there is a specific Clouseau instance to hook up.

dev/remsh

@@ -23,6 +23,12 @@ if [ -z $HOST ]; then
     HOST="127.0.0.1"
 fi
 
+if [ -n "$COOKIE" ]; then
+    _cookie_flag="-setcookie $COOKIE"
+else
+    _cookie_flag=""
+fi
+
 NAME="remsh$$@$HOST"
 NODE="node$NODE@$HOST"
-erl -name $NAME -remsh $NODE -hidden
+erl -name $NAME -remsh $NODE -hidden ${_cookie_flag}

dev/remsh-tls

@@ -23,7 +23,13 @@ if [ -z $HOST ]; then
     HOST="127.0.0.1"
 fi
 
+if [ -n "$COOKIE" ]; then
+    _cookie_flag="-setcookie $COOKIE"
+else
+    _cookie_flag=""
+fi
+
 NAME="remsh$$@$HOST"
 NODE="node$NODE@$HOST"
 rootdir="$(cd "${0%/*}" 2>/dev/null; echo "$PWD")"
-erl -name $NAME -remsh $NODE -hidden -proto_dist inet_tls -ssl_dist_optfile "${rootdir}/couch_ssl_dist.conf"
+erl -name $NAME -remsh $NODE -hidden -proto_dist inet_tls -ssl_dist_optfile "${rootdir}/couch_ssl_dist.conf" ${_cookie_flag}

dev/run

@@ -226,6 +226,12 @@ def get_args_parser():
         default=[],
         help="Path to config to place in 'local.d'. Can be repeated",
     )
+    parser.add_option(
+        "--erlang-cookie",
+        metavar="COOKIE_STRING",
+        dest="erlang_cookie",
+        help="Set Erlang cookie explicitly for inter-node communication",
+    )
     return parser
 
 
@@ -255,6 +261,7 @@ def setup_context(opts, args):
         "procs": [],
         "auto_ports": opts.auto_ports,
         "locald_configs": opts.locald_configs,
+        "erlang_cookie": opts.erlang_cookie,
     }
 
 
@@ -290,6 +297,7 @@ def setup_configs(ctx):
         cluster_port, backend_port, prometheus_port = get_ports(
             ctx, idx + ctx["node_number"]
         )
+        cookie = ctx["erlang_cookie"]
         env = {
             "prefix": toposixpath(ctx["rootdir"]),
             "package_author_name": "The Apache Software Foundation",
@@ -303,6 +311,7 @@ def setup_configs(ctx):
                 ensure_dir_exists(ctx["devdir"], "lib", node, "data")
             ),
             "node_name": "-name %s@127.0.0.1" % node,
+            "erlang_cookie": "-setcookie %s" % cookie if cookie else "",
             "cluster_port": cluster_port,
             "backend_port": backend_port,
             "prometheus_port": prometheus_port,

rel/overlay/etc/vm.args

@@ -38,8 +38,7 @@
 {{node_name}}
 
 # All nodes must share the same magic cookie for distributed Erlang to work.
-# Uncomment the following line and append a securely generated random value.
-# -setcookie
+{{erlang_cookie}}
 
 # Which interfaces should the node listen on?
 -kernel inet_dist_use_interface {127,0,0,1}