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reconcile_role.go
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reconcile_role.go
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/*
Copyright 2017 The Kubernetes 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 reconciliation
import (
"fmt"
"reflect"
rbacv1 "k8s.io/api/rbac/v1"
"k8s.io/apimachinery/pkg/api/equality"
"k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/runtime"
"k8s.io/kubernetes/pkg/registry/rbac/validation"
)
type ReconcileOperation string
var (
ReconcileCreate ReconcileOperation = "create"
ReconcileUpdate ReconcileOperation = "update"
ReconcileRecreate ReconcileOperation = "recreate"
ReconcileNone ReconcileOperation = "none"
)
type RuleOwnerModifier interface {
Get(namespace, name string) (RuleOwner, error)
Create(RuleOwner) (RuleOwner, error)
Update(RuleOwner) (RuleOwner, error)
}
type RuleOwner interface {
GetObject() runtime.Object
GetNamespace() string
GetName() string
GetLabels() map[string]string
SetLabels(map[string]string)
GetAnnotations() map[string]string
SetAnnotations(map[string]string)
GetRules() []rbacv1.PolicyRule
SetRules([]rbacv1.PolicyRule)
GetAggregationRule() *rbacv1.AggregationRule
SetAggregationRule(*rbacv1.AggregationRule)
DeepCopyRuleOwner() RuleOwner
}
type ReconcileRoleOptions struct {
// Role is the expected role that will be reconciled
Role RuleOwner
// Confirm indicates writes should be performed. When false, results are returned as a dry-run.
Confirm bool
// RemoveExtraPermissions indicates reconciliation should remove extra permissions from an existing role
RemoveExtraPermissions bool
// Client is used to look up existing roles, and create/update the role when Confirm=true
Client RuleOwnerModifier
}
type ReconcileClusterRoleResult struct {
// Role is the reconciled role from the reconciliation operation.
// If the reconcile was performed as a dry-run, or the existing role was protected, the reconciled role is not persisted.
Role RuleOwner
// MissingRules contains expected rules that were missing from the currently persisted role
MissingRules []rbacv1.PolicyRule
// ExtraRules contains extra permissions the currently persisted role had
ExtraRules []rbacv1.PolicyRule
// MissingAggregationRuleSelectors contains expected selectors that were missing from the currently persisted role
MissingAggregationRuleSelectors []metav1.LabelSelector
// ExtraAggregationRuleSelectors contains extra selectors the currently persisted role had
ExtraAggregationRuleSelectors []metav1.LabelSelector
// Operation is the API operation required to reconcile.
// If no reconciliation was needed, it is set to ReconcileNone.
// If options.Confirm == false, the reconcile was in dry-run mode, so the operation was not performed.
// If result.Protected == true, the role opted out of reconciliation, so the operation was not performed.
// Otherwise, the operation was performed.
Operation ReconcileOperation
// Protected indicates an existing role prevented reconciliation
Protected bool
}
func (o *ReconcileRoleOptions) Run() (*ReconcileClusterRoleResult, error) {
return o.run(0)
}
func (o *ReconcileRoleOptions) run(attempts int) (*ReconcileClusterRoleResult, error) {
// This keeps us from retrying forever if a role keeps appearing and disappearing as we reconcile.
// Conflict errors on update are handled at a higher level.
if attempts > 2 {
return nil, fmt.Errorf("exceeded maximum attempts")
}
var result *ReconcileClusterRoleResult
existing, err := o.Client.Get(o.Role.GetNamespace(), o.Role.GetName())
switch {
case errors.IsNotFound(err):
aggregationRule := o.Role.GetAggregationRule()
if aggregationRule == nil {
aggregationRule = &rbacv1.AggregationRule{}
}
result = &ReconcileClusterRoleResult{
Role: o.Role,
MissingRules: o.Role.GetRules(),
MissingAggregationRuleSelectors: aggregationRule.ClusterRoleSelectors,
Operation: ReconcileCreate,
}
case err != nil:
return nil, err
default:
result, err = computeReconciledRole(existing, o.Role, o.RemoveExtraPermissions)
if err != nil {
return nil, err
}
}
// If reconcile-protected, short-circuit
if result.Protected {
return result, nil
}
// If we're in dry-run mode, short-circuit
if !o.Confirm {
return result, nil
}
switch result.Operation {
case ReconcileCreate:
created, err := o.Client.Create(result.Role)
// If created since we started this reconcile, re-run
if errors.IsAlreadyExists(err) {
return o.run(attempts + 1)
}
if err != nil {
return nil, err
}
result.Role = created
case ReconcileUpdate:
updated, err := o.Client.Update(result.Role)
// If deleted since we started this reconcile, re-run
if errors.IsNotFound(err) {
return o.run(attempts + 1)
}
if err != nil {
return nil, err
}
result.Role = updated
case ReconcileNone:
// no-op
default:
return nil, fmt.Errorf("invalid operation: %v", result.Operation)
}
return result, nil
}
// computeReconciledRole returns the role that must be created and/or updated to make the
// existing role's permissions match the expected role's permissions
func computeReconciledRole(existing, expected RuleOwner, removeExtraPermissions bool) (*ReconcileClusterRoleResult, error) {
result := &ReconcileClusterRoleResult{Operation: ReconcileNone}
result.Protected = (existing.GetAnnotations()[rbacv1.AutoUpdateAnnotationKey] == "false")
// Start with a copy of the existing object
result.Role = existing.DeepCopyRuleOwner()
// Merge expected annotations and labels
result.Role.SetAnnotations(merge(expected.GetAnnotations(), result.Role.GetAnnotations()))
if !reflect.DeepEqual(result.Role.GetAnnotations(), existing.GetAnnotations()) {
result.Operation = ReconcileUpdate
}
result.Role.SetLabels(merge(expected.GetLabels(), result.Role.GetLabels()))
if !reflect.DeepEqual(result.Role.GetLabels(), existing.GetLabels()) {
result.Operation = ReconcileUpdate
}
// Compute extra and missing rules
_, result.ExtraRules = validation.Covers(expected.GetRules(), existing.GetRules())
_, result.MissingRules = validation.Covers(existing.GetRules(), expected.GetRules())
switch {
case !removeExtraPermissions && len(result.MissingRules) > 0:
// add missing rules in the union case
result.Role.SetRules(append(result.Role.GetRules(), result.MissingRules...))
result.Operation = ReconcileUpdate
case removeExtraPermissions && (len(result.MissingRules) > 0 || len(result.ExtraRules) > 0):
// stomp to expected rules in the non-union case
result.Role.SetRules(expected.GetRules())
result.Operation = ReconcileUpdate
}
// Compute extra and missing rules
_, result.ExtraAggregationRuleSelectors = aggregationRuleCovers(expected.GetAggregationRule(), existing.GetAggregationRule())
_, result.MissingAggregationRuleSelectors = aggregationRuleCovers(existing.GetAggregationRule(), expected.GetAggregationRule())
switch {
case expected.GetAggregationRule() == nil && existing.GetAggregationRule() != nil:
// we didn't expect this to be an aggregated role at all, remove the existing aggregation
result.Role.SetAggregationRule(nil)
result.Operation = ReconcileUpdate
case !removeExtraPermissions && len(result.MissingAggregationRuleSelectors) > 0:
// add missing rules in the union case
aggregationRule := result.Role.GetAggregationRule()
if aggregationRule == nil {
aggregationRule = &rbacv1.AggregationRule{}
}
aggregationRule.ClusterRoleSelectors = append(aggregationRule.ClusterRoleSelectors, result.MissingAggregationRuleSelectors...)
result.Role.SetAggregationRule(aggregationRule)
result.Operation = ReconcileUpdate
case removeExtraPermissions && (len(result.MissingAggregationRuleSelectors) > 0 || len(result.ExtraAggregationRuleSelectors) > 0):
result.Role.SetAggregationRule(expected.GetAggregationRule())
result.Operation = ReconcileUpdate
}
return result, nil
}
// merge combines the given maps with the later annotations having higher precedence
func merge(maps ...map[string]string) map[string]string {
var output map[string]string = nil
for _, m := range maps {
if m != nil && output == nil {
output = map[string]string{}
}
for k, v := range m {
output[k] = v
}
}
return output
}
// aggregationRuleCovers determines whether or not the ownerSelectors cover the servantSelectors in terms of semantically
// equal label selectors.
// It returns whether or not the ownerSelectors cover and a list of the rules that the ownerSelectors do not cover.
func aggregationRuleCovers(ownerRule, servantRule *rbacv1.AggregationRule) (bool, []metav1.LabelSelector) {
switch {
case ownerRule == nil && servantRule == nil:
return true, []metav1.LabelSelector{}
case ownerRule == nil && servantRule != nil:
return false, servantRule.ClusterRoleSelectors
case ownerRule != nil && servantRule == nil:
return true, []metav1.LabelSelector{}
}
ownerSelectors := ownerRule.ClusterRoleSelectors
servantSelectors := servantRule.ClusterRoleSelectors
uncoveredSelectors := []metav1.LabelSelector{}
for _, servantSelector := range servantSelectors {
covered := false
for _, ownerSelector := range ownerSelectors {
if equality.Semantic.DeepEqual(ownerSelector, servantSelector) {
covered = true
break
}
}
if !covered {
uncoveredSelectors = append(uncoveredSelectors, servantSelector)
}
}
return (len(uncoveredSelectors) == 0), uncoveredSelectors
}