+sub assert_we_can_join_cluster_version {
+ my ($version) = @_;
+ my $min_version = JOIN_API_VERSION - JOIN_API_AGE_AS_JOINEE;
+ return if $version >= $min_version;
+ die "error: incompatible join API version on cluster ($version), local node"
+ ." has ". JOIN_API_VERSION ." and supports >= $min_version. Make sure"
+ ."all cluster nodes are up-to-date.\n";
+}
+
+sub assert_node_can_join_our_version {
+ my ($version) = @_;
+ my $min_version = JOIN_API_VERSION - JOIN_API_AGE_AS_CLUSTER;
+ return if $version >= $min_version;
+ die "error: unsupported old API version on joining node ($version), cluster"
+ ." node has ". JOIN_API_VERSION ." and supports >= $min_version. Please"
+ ." upgrade node before joining\n";
+}
+