[pve-devel] [RFC PATCH ha-manager 2/2] rules: node affinity: implement negative node affinity rules

[Daniel Kral <d.kral@proxmox.com>]

Extend the existing node affinity rules plugin to allow users to specify
negative node affinity constraints, which specify the nodes where HA
resources SHOULD NOT/MUST NOT be placed.

Negative node affinity rules are internally represented as positive node
affinity rules, where the positive node affinity rules' nodes set is the
set complement of the negative node affinity rules' node set. As this is
semantically equivalent, this allows no change in the apply logic.

As node priority groups do only hold semantic value for positive node
affinity rules, add all resulting nodes to the default priority group.

Signed-off-by: Daniel Kral <d.kral@proxmox.com>
---
 src/PVE/HA/HashTools.pm                       | 20 +++++++
 src/PVE/HA/Rules.pm                           |  2 +
 src/PVE/HA/Rules/NodeAffinity.pm              | 59 ++++++++++++++++++-
 .../defaults-for-node-affinity-rules.cfg      | 15 +++++
 ...efaults-for-node-affinity-rules.cfg.expect | 58 +++++++++++++++++-
 5 files changed, 151 insertions(+), 3 deletions(-)

diff --git a/src/PVE/HA/HashTools.pm b/src/PVE/HA/HashTools.pm
index ebe47e38..b6e2136b 100644
--- a/src/PVE/HA/HashTools.pm
+++ b/src/PVE/HA/HashTools.pm
@@ -6,6 +6,7 @@ use warnings;
 use base qw(Exporter);
 
 our @EXPORT_OK = qw(
+    set_difference
     set_intersect
     set_union
     sets_are_disjoint
@@ -29,6 +30,25 @@ more verbose implementation.
 
 =cut
 
+=head3 set_difference($hash1, $hash2)
+
+Returns a hash set of the set difference between the hash sets C<$hash1> and
+C<$hash2>, i.e. the elements that are in C<$hash1> without the elements that
+are in C<$hash2>.
+
+The hashes C<$hash1> and C<$hash2> are expected to be hash sets, i.e.
+key-value pairs are always set to C<1> or another truthy value.
+
+=cut
+
+sub set_difference : prototype($$) {
+    my ($hash1, $hash2) = @_;
+
+    my $result = { map { $hash2->{$_} ? () : ($_ => 1) } keys %$hash1 };
+
+    return $result;
+}
+
 =head3 set_intersect($hash1, $hash2)
 
 Returns a hash set of the intersection of the hash sets C<$hash1> and
diff --git a/src/PVE/HA/Rules.pm b/src/PVE/HA/Rules.pm
index c4a2ccea..7f9f428d 100644
--- a/src/PVE/HA/Rules.pm
+++ b/src/PVE/HA/Rules.pm
@@ -459,6 +459,8 @@ sub transform {
         for my $transform ($transformdef->{$type}->@*) {
             my $global_args = $class->get_check_arguments($rules);
 
+            $global_args->{nodes} = $nodes;
+
             $transform->($rules, $global_args);
         }
     }
diff --git a/src/PVE/HA/Rules/NodeAffinity.pm b/src/PVE/HA/Rules/NodeAffinity.pm
index 1f15ae2d..cdf67a55 100644
--- a/src/PVE/HA/Rules/NodeAffinity.pm
+++ b/src/PVE/HA/Rules/NodeAffinity.pm
@@ -9,6 +9,7 @@ use PVE::Cluster;
 use PVE::JSONSchema qw(get_standard_option);
 use PVE::Tools;
 
+use PVE::HA::HashTools qw(set_difference);
 use PVE::HA::Rules;
 use PVE::HA::Tools;
 
@@ -28,6 +29,22 @@ PVE::HA::Rules::NodeAffinity
 This package provides the capability to specify and apply rules, which put
 affinity constraints between a set of HA resources and a set of nodes.
 
+HA Node Affinity rules can be one of two types:
+
+=over
+
+=item C<'positive'>
+
+Positive node affinity rules specify the nodes, which SHOULD/MUST be preferred
+by the given HA resources.
+
+=item C<'negative'>
+
+Positive node affinity rules specify the nodes, which SHOULD NOT/MUST NOT be
+preferred by the given HA resources.
+
+=back
+
 HA Node Affinity rules can be either C<'non-strict'> or C<'strict'>:
 
 =over
@@ -66,9 +83,10 @@ sub properties {
         ),
         affinity => {
             description => "Describes whether the HA resources are supposed to"
-                . " be placed on the given nodes ('positive').",
+                . " be placed on the given nodes ('positive'), or are supposed"
+                . " to be placed on any but the given nodes ('negative').",
             type => 'string',
-            enum => ['positive'],
+            enum => ['positive', 'negative'],
             default => 'positive',
             optional => 1,
         },
@@ -256,6 +274,43 @@ __PACKAGE__->register_check(
     },
 );
 
+=head1 NODE AFFINITY RULE TRANSFORMATION HELPERS
+
+=cut
+
+=head3 invert_negative_node_affinity_rules($rules, $node_affinity_rules, $nodes)
+
+Modifies C<$rules> such that all negative node affinity rules, defined in
+C<$node_affinity_rules>, are transformed to positive node affinity rules, where
+the nodes set is the complement of the negative node affinity rules' nodes set.
+
+=cut
+
+sub invert_negative_node_affinity_rules {
+    my ($rules, $node_affinity_rules, $nodes) = @_;
+
+    my $cluster_nodes = { map { $_ => 1 } @$nodes };
+
+    while (my ($node_affinity_id, $node_affinity_rule) = each %$node_affinity_rules) {
+        next if $node_affinity_rule->{affinity} ne 'negative';
+
+        my $positive_nodes = { map { $_ => 1 } keys $node_affinity_rule->{nodes}->%* };
+        my $new_nodes = set_difference($cluster_nodes, $positive_nodes);
+        $new_nodes->{$_} = { priority => 0 } for keys %$new_nodes;
+
+        $rules->{ids}->{$node_affinity_id}->{affinity} = 'positive';
+        $rules->{ids}->{$node_affinity_id}->{nodes} = $new_nodes;
+    }
+}
+
+__PACKAGE__->register_transform(sub {
+    my ($rules, $args) = @_;
+
+    invert_negative_node_affinity_rules(
+        $rules, $args->{node_affinity_rules}, $args->{nodes},
+    );
+});
+
 =head1 NODE AFFINITY RULE HELPERS
 
 =cut
diff --git a/src/test/rules_cfgs/defaults-for-node-affinity-rules.cfg b/src/test/rules_cfgs/defaults-for-node-affinity-rules.cfg
index 27658562..b89d725d 100644
--- a/src/test/rules_cfgs/defaults-for-node-affinity-rules.cfg
+++ b/src/test/rules_cfgs/defaults-for-node-affinity-rules.cfg
@@ -20,3 +20,18 @@ node-affinity: node-affinity-strict
 	resources vm:104
 	nodes node3
 	strict 1
+
+# Case 5: Non-strict negative node affinity rule is transformed to positive node affinity rule with complement node set
+#         and specified nodes as fallback internally.
+node-affinity: negative-node-affinity-defaults
+	resources vm:105
+	nodes node2
+	affinity negative
+
+# Case 6: Strict negative node affinity rule is transformed to positive node affinity rule with complement node set
+#         internally.
+node-affinity: negative-node-affinity-strict
+	resources vm:106
+	nodes node3
+	affinity negative
+	strict 1
diff --git a/src/test/rules_cfgs/defaults-for-node-affinity-rules.cfg.expect b/src/test/rules_cfgs/defaults-for-node-affinity-rules.cfg.expect
index 0d6e5605..877f1967 100644
--- a/src/test/rules_cfgs/defaults-for-node-affinity-rules.cfg.expect
+++ b/src/test/rules_cfgs/defaults-for-node-affinity-rules.cfg.expect
@@ -1,8 +1,39 @@
 --- Log ---
 --- Config ---
 {
-   "digest" : "fcad82def12abc4422061b79cfd0399967053d93",
+   "digest" : "308a8b704d8b4dc3fb83d8c97c86133caf735755",
    "ids" : {
+      "negative-node-affinity-defaults" : {
+         "affinity" : "positive",
+         "nodes" : {
+            "node1" : {
+               "priority" : 0
+            },
+            "node3" : {
+               "priority" : 0
+            }
+         },
+         "resources" : {
+            "vm:105" : 1
+         },
+         "type" : "node-affinity"
+      },
+      "negative-node-affinity-strict" : {
+         "affinity" : "positive",
+         "nodes" : {
+            "node1" : {
+               "priority" : 0
+            },
+            "node2" : {
+               "priority" : 0
+            }
+         },
+         "resources" : {
+            "vm:106" : 1
+         },
+         "strict" : 1,
+         "type" : "node-affinity"
+      },
       "node-affinity-defaults" : {
          "affinity" : "positive",
          "nodes" : {
@@ -56,6 +87,8 @@
       }
    },
    "order" : {
+      "negative-node-affinity-defaults" : 5,
+      "negative-node-affinity-strict" : 6,
       "node-affinity-defaults" : 1,
       "node-affinity-disabled" : 2,
       "node-affinity-disabled-explicit" : 3,
@@ -84,6 +117,29 @@
                "priority" : 0
             }
          }
+      },
+      "vm:105" : {
+         "nodes" : {
+            "node1" : {
+               "priority" : 0
+            },
+            "node2" : {
+               "priority" : -1
+            },
+            "node3" : {
+               "priority" : 0
+            }
+         }
+      },
+      "vm:106" : {
+         "nodes" : {
+            "node1" : {
+               "priority" : 0
+            },
+            "node2" : {
+               "priority" : 0
+            }
+         }
       }
    },
    "resource-affinity" : {
-- 
2.47.3



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