[PATCH ha-manager v2 03/12] 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 making no change in the apply logic.

As node priority groups do only hold semantic value for positive node
affinity rules, reject negative node affinity rules with non-zero
priorities and add all resulting nodes to the default priority group.

Furthermore, negative node affinity rules, which specify all cluster
nodes, are dropped as well as their strict variant is unsatisfiable,
because they effectively restrict HA resource to an empty node set, and
the non-strict variant is equivalent to no rule at all.

Signed-off-by: Daniel Kral <d.kral@proxmox.com>
---
changes since v1:
- add rule checker to disallow specifying node priorities for negative
  node affinity rules (thanks @Fiona!)
- add rule checker to disallow specifying all cluster nodes
- rename s/nodes/cluster-nodes/ arguments (thanks @Fiona!)
- rename wrongly named 'positive_nodes' to 'negative_nodes'
- add more test cases

 src/PVE/HA/HashTools.pm                       |  20 +++
 src/PVE/HA/Rules.pm                           |   2 +
 src/PVE/HA/Rules/NodeAffinity.pm              | 162 +++++++++++++++++-
 .../defaults-for-node-affinity-rules.cfg      |  15 ++
 ...efaults-for-node-affinity-rules.cfg.expect |  58 ++++++-
 ...effective-negative-node-affinity-rules.cfg |  12 ++
 ...ve-negative-node-affinity-rules.cfg.expect |  17 ++
 ...iority-in-negative-node-affinity-rules.cfg |  11 ++
 ...in-negative-node-affinity-rules.cfg.expect |  45 +++++
 9 files changed, 339 insertions(+), 3 deletions(-)
 create mode 100644 src/test/rules_cfgs/ineffective-negative-node-affinity-rules.cfg
 create mode 100644 src/test/rules_cfgs/ineffective-negative-node-affinity-rules.cfg.expect
 create mode 100644 src/test/rules_cfgs/node-priority-in-negative-node-affinity-rules.cfg
 create mode 100644 src/test/rules_cfgs/node-priority-in-negative-node-affinity-rules.cfg.expect

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 2b48cb60..bc67de20 100644
--- a/src/PVE/HA/Rules.pm
+++ b/src/PVE/HA/Rules.pm
@@ -461,6 +461,8 @@ sub transform {
         for my $transform ($transformdef->{$type}->@*) {
             my $global_args = $class->get_check_arguments($rules);
 
+            $global_args->{'cluster-nodes'} = $cluster_nodes;
+
             $transform->($rules, $global_args);
         }
     }
diff --git a/src/PVE/HA/Rules/NodeAffinity.pm b/src/PVE/HA/Rules/NodeAffinity.pm
index 5d4401f6..bbe76720 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'>
+
+Negative node affinity rules specify the nodes, which SHOULD/MUST be avoided 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 +274,146 @@ __PACKAGE__->register_check(
     },
 );
 
+=head3 check_nonempty_negative_nodes_complement($node_affinity_rules, $cluster_nodes)
+
+Returns a list of negative node affinity rule ids in C<$node_affinity_rules>,
+where the complement of the negative node set is an empty node set according to
+the currently configured cluster node list C<$cluster_nodes>, i.e., the
+negative node set specifies all cluster nodes.
+
+Even though this is only relevant for strict negative node affinity rules, this
+check also includes non-strict negative node affinity rules as their effective
+node set would be equivalent to setting no rule at all.
+
+If there are none, the returned list is empty.
+
+=cut
+
+sub check_nonempty_negative_nodes_complement {
+    my ($node_affinity_rules, $cluster_nodes) = @_;
+
+    my @conflicts = ();
+
+    my $total_node_count = @$cluster_nodes;
+
+    while (my ($ruleid, $rule) = each %$node_affinity_rules) {
+        next if $rule->{affinity} ne 'negative';
+
+        push @conflicts, $ruleid if keys $rule->{nodes}->%* >= $total_node_count;
+    }
+
+    @conflicts = sort @conflicts;
+    return \@conflicts;
+}
+
+__PACKAGE__->register_check(
+    sub {
+        my ($args) = @_;
+
+        return check_nonempty_negative_nodes_complement(
+            $args->{node_affinity_rules},
+            $args->{'cluster-nodes'},
+        );
+    },
+    sub {
+        my ($ruleids, $errors) = @_;
+
+        for my $ruleid (@$ruleids) {
+            push $errors->{$ruleid}->{nodes}->@*,
+                "negative node affinity rule must not specify all cluster nodes";
+        }
+    },
+);
+
+=head3 check_unprioritized_negative_nodes($node_affinity_rules)
+
+Returns a list of negative node affinity rule ids in C<$node_affinity_rules>,
+where at least one node has a priority set. A node priority does not have any
+meaningful semantic value for negative node affinity rules.
+
+If there are none, the returned list is empty.
+
+=cut
+
+sub check_unprioritized_negative_nodes {
+    my ($node_affinity_rules) = @_;
+
+    my @conflicts = ();
+
+    while (my ($ruleid, $rule) = each %$node_affinity_rules) {
+        next if $rule->{affinity} ne 'negative';
+
+        for my $node (keys $rule->{nodes}->%*) {
+            if ($rule->{nodes}->{$node}->{priority}) {
+                push @conflicts, $ruleid;
+                last; # one non-zero priority is enough to invalidate rule
+            }
+        }
+    }
+
+    @conflicts = sort @conflicts;
+    return \@conflicts;
+}
+
+__PACKAGE__->register_check(
+    sub {
+        my ($args) = @_;
+
+        return check_unprioritized_negative_nodes($args->{node_affinity_rules});
+    },
+    sub {
+        my ($ruleids, $errors) = @_;
+
+        for my $ruleid (@$ruleids) {
+            push $errors->{$ruleid}->{nodes}->@*,
+                "negative node affinity rule must not specify node priorities";
+        }
+    },
+);
+
+=head1 NODE AFFINITY RULE TRANSFORMATION HELPERS
+
+=cut
+
+=head3 invert_negative_node_affinity_rules($rules, $node_affinity_rules, $cluster_nodes)
+
+Modifies C<$rules> such that all negative node affinity rules, defined in
+C<$node_affinity_rules>, are transformed to positive node affinity rules, where
+the nodes set is the complement of the negative node affinity rules' nodes set.
+
+C<$cluster_nodes> is a list of the configured cluster nodes, which is used as
+the universal set to build the complement node set.
+
+=cut
+
+sub invert_negative_node_affinity_rules {
+    my ($rules, $node_affinity_rules, $cluster_nodes) = @_;
+
+    # set_difference(...) requires a hash set instead of a list
+    my $cluster_nodes_hash = { map { $_ => 1 } @$cluster_nodes };
+
+    while (my ($node_affinity_id, $node_affinity_rule) = each %$node_affinity_rules) {
+        next if $node_affinity_rule->{affinity} ne 'negative';
+
+        my $negative_nodes = { map { $_ => 1 } keys $node_affinity_rule->{nodes}->%* };
+        my $positive_nodes = set_difference($cluster_nodes_hash, $negative_nodes);
+        $positive_nodes->{$_} = { priority => 0 } for keys %$positive_nodes;
+
+        $rules->{ids}->{$node_affinity_id}->{affinity} = 'positive';
+        $rules->{ids}->{$node_affinity_id}->{nodes} = $positive_nodes;
+    }
+}
+
+__PACKAGE__->register_transform(sub {
+    my ($rules, $args) = @_;
+
+    invert_negative_node_affinity_rules(
+        $rules,
+        $args->{node_affinity_rules},
+        $args->{'cluster-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" : {
diff --git a/src/test/rules_cfgs/ineffective-negative-node-affinity-rules.cfg b/src/test/rules_cfgs/ineffective-negative-node-affinity-rules.cfg
new file mode 100644
index 00000000..a238799a
--- /dev/null
+++ b/src/test/rules_cfgs/ineffective-negative-node-affinity-rules.cfg
@@ -0,0 +1,12 @@
+# Case 1: Remove non-strict negative node affinity rule, which specifies all cluster nodes.
+node-affinity: nonstrict-negative-node-affinity-with-all-cluster-nodes
+    resources vm:101
+    nodes node1,node2,node3
+    affinity negative
+
+# Case 2: Remove strict negative node affinity rule, which specifies all cluster nodes.
+node-affinity: strict-negative-node-affinity-with-all-cluster-nodes
+    resources vm:102
+    nodes node1,node2,node3
+    affinity negative
+    strict
diff --git a/src/test/rules_cfgs/ineffective-negative-node-affinity-rules.cfg.expect b/src/test/rules_cfgs/ineffective-negative-node-affinity-rules.cfg.expect
new file mode 100644
index 00000000..dec03663
--- /dev/null
+++ b/src/test/rules_cfgs/ineffective-negative-node-affinity-rules.cfg.expect
@@ -0,0 +1,17 @@
+--- Log ---
+Drop rule 'nonstrict-negative-node-affinity-with-all-cluster-nodes', because negative node affinity rule must not specify all cluster nodes.
+Drop rule 'strict-negative-node-affinity-with-all-cluster-nodes', because negative node affinity rule must not specify all cluster nodes.
+--- Config ---
+{
+   "digest" : "7a68821f23f0b5b110bfac64a66fd7a01564dd74",
+   "ids" : {},
+   "order" : {}
+}
+--- Compiled Config ---
+{
+   "node-affinity" : {},
+   "resource-affinity" : {
+      "negative" : {},
+      "positive" : {}
+   }
+}
diff --git a/src/test/rules_cfgs/node-priority-in-negative-node-affinity-rules.cfg b/src/test/rules_cfgs/node-priority-in-negative-node-affinity-rules.cfg
new file mode 100644
index 00000000..64a2fd63
--- /dev/null
+++ b/src/test/rules_cfgs/node-priority-in-negative-node-affinity-rules.cfg
@@ -0,0 +1,11 @@
+# Case 1: Do not remove negative node affinity rules with node priorities set to zero as it is equivalent to no node priorities set at all.
+node-affinity: negative-node-affinity-with-default-node-priorities
+    resources vm:101
+    nodes node1:0,node2:0
+    affinity negative
+
+# Case 2: Remove negative node affinity rules with non-zero node priorities.
+node-affinity: negative-node-affinity-with-non-zero-node-priorities
+    resources vm:102
+    nodes node1:2,node2:1
+    affinity negative
diff --git a/src/test/rules_cfgs/node-priority-in-negative-node-affinity-rules.cfg.expect b/src/test/rules_cfgs/node-priority-in-negative-node-affinity-rules.cfg.expect
new file mode 100644
index 00000000..ef50b25e
--- /dev/null
+++ b/src/test/rules_cfgs/node-priority-in-negative-node-affinity-rules.cfg.expect
@@ -0,0 +1,45 @@
+--- Log ---
+Drop rule 'negative-node-affinity-with-non-zero-node-priorities', because negative node affinity rule must not specify node priorities.
+--- Config ---
+{
+   "digest" : "d95cf03b7f6c8078854506cc79127fd942b868bd",
+   "ids" : {
+      "negative-node-affinity-with-default-node-priorities" : {
+         "affinity" : "positive",
+         "nodes" : {
+            "node3" : {
+               "priority" : 0
+            }
+         },
+         "resources" : {
+            "vm:101" : 1
+         },
+         "type" : "node-affinity"
+      }
+   },
+   "order" : {
+      "negative-node-affinity-with-default-node-priorities" : 1
+   }
+}
+--- Compiled Config ---
+{
+   "node-affinity" : {
+      "vm:101" : {
+         "nodes" : {
+            "node1" : {
+               "priority" : -1
+            },
+            "node2" : {
+               "priority" : -1
+            },
+            "node3" : {
+               "priority" : 0
+            }
+         }
+      }
+   },
+   "resource-affinity" : {
+      "negative" : {},
+      "positive" : {}
+   }
+}
-- 
2.47.3