[pve-devel] [PATCH cluster 4/5] Add cluster join API version check

[Stefan Reiter]

Adds API call GET /cluster/config/apiversion to retrieve remote clusters
join-API version (0 is assumed for versions without this endpoint).

Warn user if remote version differs, and select new fallback method only
if available. This ensures full compatibility between nodes/clusters
with and without new fallback behaviour.

Signed-off-by: Stefan Reiter <s.reiter at proxmox.com>
---

Technically optional, but needed to ensure full compatibility across versions
before and after this series.

 data/PVE/API2/ClusterConfig.pm | 18 ++++++++++++++++++
 data/PVE/Cluster/Setup.pm      | 16 ++++++++++++++--
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/data/PVE/API2/ClusterConfig.pm b/data/PVE/API2/ClusterConfig.pm
index 2d15f97..bff0c48 100644
--- a/data/PVE/API2/ClusterConfig.pm
+++ b/data/PVE/API2/ClusterConfig.pm
@@ -58,11 +58,29 @@ __PACKAGE__->register_method({
 	    { name => 'totem' },
 	    { name => 'join' },
 	    { name => 'qdevice' },
+	    { name => 'apiversion' },
 	];
 
 	return $result;
     }});
 
+__PACKAGE__->register_method ({
+    name => 'join_api_version',
+    path => 'apiversion',
+    method => 'GET',
+    description => "Return the version of the cluster join API available on this node.",
+    permissions => {
+	check => ['perm', '/', [ 'Sys.Audit' ]],
+    },
+    parameters => {
+	additionalProperties => 0,
+	properties => {},
+    },
+    returns => { type => 'integer' },
+    code => sub {
+	return PVE::Cluster::Setup::JOIN_API_VERSION;
+    }});
+
 __PACKAGE__->register_method ({
     name => 'create',
     path => '',
diff --git a/data/PVE/Cluster/Setup.pm b/data/PVE/Cluster/Setup.pm
index 9850299..c6f6c9e 100644
--- a/data/PVE/Cluster/Setup.pm
+++ b/data/PVE/Cluster/Setup.pm
@@ -19,6 +19,8 @@ use PVE::JSONSchema;
 use PVE::Network;
 use PVE::Tools;
 
+use constant JOIN_API_VERSION => 1;
+
 my $pmxcfs_base_dir = PVE::Cluster::base_dir();
 my $pmxcfs_auth_dir = PVE::Cluster::auth_dir();
 
@@ -660,6 +662,13 @@ sub join {
     # login raises an exception on failure, so if we get here we're good
     print "Login succeeded.\n";
 
+    # check cluster join API version and warn user
+    my $apiver = eval { $conn->get("/cluster/config/apiversion"); } // 0;
+    warn "warning: local join API version (" . JOIN_API_VERSION . ") differs"
+       . " from remote ($apiver), make sure all nodes are upgraded to the"
+       . " latest version. Cluster join might fail!\n"
+	if $apiver != JOIN_API_VERSION;
+
     my $args = {};
     $args->{force} = $param->{force} if defined($param->{force});
     $args->{nodeid} = $param->{nodeid} if $param->{nodeid};
@@ -668,8 +677,11 @@ sub join {
 	$args->{"link$link"} = PVE::Corosync::print_corosync_link($links->{$link});
     }
 
-    # this will be used as fallback if no links are specified
-    $args->{new_node_ip} = $local_ip_address;
+    # specify fallback if no links are given according to remote api version
+    if (!%$links) {
+	$args->{link0} = $local_ip_address if $apiver == 0;
+	$args->{new_node_ip} = $local_ip_address if $apiver >= 1;
+    }
 
     print "No local links given, will attempt fallback to $local_ip_address\n"
 	if !%$links;
-- 
2.20.1