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destination_rule.go
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destination_rule.go
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// Copyright Istio Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package model
import (
"fmt"
"k8s.io/apimachinery/pkg/types"
networking "istio.io/api/networking/v1alpha3"
"istio.io/istio/pkg/config"
"istio.io/istio/pkg/config/host"
"istio.io/istio/pkg/config/labels"
"istio.io/istio/pkg/config/visibility"
"istio.io/istio/pkg/util/sets"
)
// This function merges one or more destination rules for a given host string
// into a single destination rule. Note that it does not perform inheritance style merging.
// IOW, given three dest rules (*.foo.com, *.foo.com, *.com) without selectors, calling this function for
// each config will result in a final dest rule set (*.foo.com, and *.com).
//
// The following is the merge logic:
// 1. Unique subsets (based on subset name) are concatenated to the original rule's list of subsets
// 2. If the original rule did not have any top level traffic policy, traffic policies from the new rule will be
// used.
// 3. If the original rule did not have any exportTo, exportTo settings from the new rule will be used.
func (ps *PushContext) mergeDestinationRule(p *consolidatedDestRules, destRuleConfig config.Config, exportToSet sets.Set[visibility.Instance]) {
rule := destRuleConfig.Spec.(*networking.DestinationRule)
resolvedHost := ResolveShortnameToFQDN(rule.Host, destRuleConfig.Meta)
var destRules map[host.Name][]*ConsolidatedDestRule
if resolvedHost.IsWildCarded() {
destRules = p.wildcardDestRules
} else {
destRules = p.specificDestRules
}
if mdrList, exists := destRules[resolvedHost]; exists {
// `addRuleToProcessedDestRules` determines if the incoming destination rule would become a new unique entry in the processedDestRules list.
addRuleToProcessedDestRules := true
for _, mdr := range mdrList {
existingRule := mdr.rule.Spec.(*networking.DestinationRule)
bothWithoutSelector := rule.GetWorkloadSelector() == nil && existingRule.GetWorkloadSelector() == nil
bothWithSelector := existingRule.GetWorkloadSelector() != nil && rule.GetWorkloadSelector() != nil
selectorsMatch := labels.Instance(existingRule.GetWorkloadSelector().GetMatchLabels()).Equals(rule.GetWorkloadSelector().GetMatchLabels())
if bothWithSelector && !selectorsMatch {
// If the new destination rule and the existing one has workload selectors associated with them, skip merging
// if the selectors do not match
continue
}
// If both the destination rules are without a workload selector or with matching workload selectors, simply merge them.
// If the incoming rule has a workload selector, it has to be merged with the existing rules with workload selector, and
// at the same time added as a unique entry in the processedDestRules.
if bothWithoutSelector || (rule.GetWorkloadSelector() != nil && selectorsMatch) {
addRuleToProcessedDestRules = false
}
// Deep copy destination rule, to prevent mutate it later when merge with a new one.
// This can happen when there are more than one destination rule of same host in one namespace.
copied := mdr.rule.DeepCopy()
mdr.rule = &copied
mdr.from = append(mdr.from, destRuleConfig.NamespacedName())
mergedRule := copied.Spec.(*networking.DestinationRule)
existingSubset := sets.String{}
for _, subset := range mergedRule.Subsets {
existingSubset.Insert(subset.Name)
}
// we have an another destination rule for same host.
// concatenate both of them -- essentially add subsets from one to other.
// Note: we only add the subsets and do not overwrite anything else like exportTo or top level
// traffic policies if they already exist
for _, subset := range rule.Subsets {
if !existingSubset.Contains(subset.Name) {
// if not duplicated, append
mergedRule.Subsets = append(mergedRule.Subsets, subset)
} else {
// duplicate subset
ps.AddMetric(DuplicatedSubsets, string(resolvedHost), "",
fmt.Sprintf("Duplicate subset %s found while merging destination rules for %s",
subset.Name, string(resolvedHost)))
}
}
// If there is no top level policy and the incoming rule has top level
// traffic policy, use the one from the incoming rule.
if mergedRule.TrafficPolicy == nil && rule.TrafficPolicy != nil {
mergedRule.TrafficPolicy = rule.TrafficPolicy
}
// If there is no exportTo in the existing rule and
// the incoming rule has an explicit exportTo, use the
// one from the incoming rule.
if p.exportTo[resolvedHost].IsEmpty() && !exportToSet.IsEmpty() {
p.exportTo[resolvedHost] = exportToSet
}
}
if addRuleToProcessedDestRules {
destRules[resolvedHost] = append(destRules[resolvedHost], ConvertConsolidatedDestRule(&destRuleConfig))
}
return
}
// DestinationRule does not exist for the resolved host so add it
destRules[resolvedHost] = append(destRules[resolvedHost], ConvertConsolidatedDestRule(&destRuleConfig))
p.exportTo[resolvedHost] = exportToSet
}
func ConvertConsolidatedDestRule(cfg *config.Config) *ConsolidatedDestRule {
return &ConsolidatedDestRule{
rule: cfg,
from: []types.NamespacedName{cfg.NamespacedName()},
}
}
// Equals compare l equals r consolidatedDestRule or not.
func (l *ConsolidatedDestRule) Equals(r *ConsolidatedDestRule) bool {
if l == r {
return true
}
if l == nil || r == nil {
return false
}
// compare from
if len(l.from) != len(r.from) {
return false
}
for i, v := range l.from {
if v != r.from[i] {
return false
}
}
return true
}
func (l *ConsolidatedDestRule) GetRule() *config.Config {
if l == nil {
return nil
}
return l.rule
}
func (l *ConsolidatedDestRule) GetFrom() []types.NamespacedName {
if l == nil {
return nil
}
return l.from
}