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fix(bgp_policy): allow for statement add / remove

Browse Source 
The previous version of the bgp_policies code only allowed for creating
a policy when the policy didn't exist already. However, with the advent
of dual-stack we need to be able to add / remove statements if we add or
lose a specific IP family (e.g. IPv4 or IPv6) since they are handled in
different statements.

Given that the owner of GoBGP has let us know that policies are
idempotent, this now involves quite a bit of work. We need to follow the
following procedure:

add statements if missing -> add them to a policy -> if policy doesn't
  equal the one already in GoBGP -> create the new policy and associate
  it -> de-associate the old policy -> remove the old policy
This commit is contained in:
Aaron U'Ren 2023-03-19 14:59:45 -05:00 committed by Aaron U'Ren
parent 1d5c9ce25c
commit 384ed97a76
3 changed files with 311 additions and 92 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

356
pkg/controllers/routing/bgp_policies.go
View File

@ -6,8 +6,10 @@ import (
"fmt"
"net"
"reflect"
"regexp"
"sort"
"strconv"
"strings"
gobgpapi "github.com/osrg/gobgp/v3/api"
v1core "k8s.io/api/core/v1"
@ -41,6 +43,10 @@ const (
maxIPv6MaskSize = uint32(128)
)
var (
rePolicyVersionExtractor = regexp.MustCompile(`(kube_router_(?:import|export))(\d*)`)
)
// AddPolicies adds BGP import and export policies
func (nrc *NetworkRoutingController) AddPolicies() error {
// we are rr server do not add export policies
@ -579,7 +585,7 @@ func (nrc *NetworkRoutingController) addAllBGPPeersDefinedSet(
// iBGP peers
// - an option to allow overriding the next-hop-address with the outgoing ip for external bgp peers
func (nrc *NetworkRoutingController) addExportPolicies() error {
statements := make([]*gobgpapi.Statement, 0)
statementNames := make([]string, 0)
var bgpActions gobgpapi.Actions
if nrc.pathPrepend {
@ -616,8 +622,7 @@ func (nrc *NetworkRoutingController) addExportPolicies() error {
continue
}
statements = append(statements,
&gobgpapi.Statement{
statement := gobgpapi.Statement{
Conditions: &gobgpapi.Conditions{
PrefixSet: &gobgpapi.MatchSet{
Type: gobgpapi.MatchSet_ANY,
@ -629,7 +634,12 @@ func (nrc *NetworkRoutingController) addExportPolicies() error {
},
},
Actions: &actions,
})
Name: podSet + iBGPPeerSet,
}
if err = nrc.ensureStatementExists(&statement); err != nil {
return fmt.Errorf("could not check or create statement: %s - %v", statement.Name, err)
}
statementNames = append(statementNames, statement.Name)
}
}
@ -674,7 +684,7 @@ func (nrc *NetworkRoutingController) addExportPolicies() error {
continue
}
statements = append(statements, &gobgpapi.Statement{
statement := gobgpapi.Statement{
Conditions: &gobgpapi.Conditions{
PrefixSet: &gobgpapi.MatchSet{
Type: gobgpapi.MatchSet_ANY,
@ -686,7 +696,12 @@ func (nrc *NetworkRoutingController) addExportPolicies() error {
},
},
Actions: &bgpActions,
})
Name: serviceVIPSet + peerSet,
}
if err = nrc.ensureStatementExists(&statement); err != nil {
return fmt.Errorf("could not check or create statement: %s - %v", statement.Name, err)
}
statementNames = append(statementNames, statement.Name)
}
if nrc.advertisePodCidr {
@ -704,7 +719,7 @@ func (nrc *NetworkRoutingController) addExportPolicies() error {
continue
}
statements = append(statements, &gobgpapi.Statement{
statement := gobgpapi.Statement{
Conditions: &gobgpapi.Conditions{
PrefixSet: &gobgpapi.MatchSet{
Type: gobgpapi.MatchSet_ANY,
@ -716,21 +731,36 @@ func (nrc *NetworkRoutingController) addExportPolicies() error {
},
},
Actions: &bgpActions,
Name: podSet + peerSet,
}
if err = nrc.ensureStatementExists(&statement); err != nil {
return fmt.Errorf("could not check or create statement: %s - %v", statement.Name, err)
}
statementNames = append(statementNames, statement.Name)
}
}
}
}
newStatementsByName := make([]*gobgpapi.Statement, 0)
for _, st := range statementNames {
newStatementsByName = append(newStatementsByName, &gobgpapi.Statement{
Name: st,
})
}
}
}
}
definition := gobgpapi.Policy{
newPolicy := gobgpapi.Policy{
Name: kubeRouterExportPolicy,
Statements: statements,
Statements: newStatementsByName,
}
policyAlreadyExists := false
currentPolicyFound := false
currentPolicyName := ""
currentPolicySameAsNewPolicy := false
checkExistingPolicy := func(existingPolicy *gobgpapi.Policy) {
if existingPolicy.Name == kubeRouterExportPolicy {
policyAlreadyExists = true
if strings.HasPrefix(existingPolicy.Name, kubeRouterExportPolicy) {
currentPolicyFound = true
currentPolicyName = existingPolicy.Name
currentPolicySameAsNewPolicy = statementsEqualByName(existingPolicy.Statements, newPolicy.Statements)
}
}
err := nrc.bgpServer.ListPolicy(context.Background(), &gobgpapi.ListPolicyRequest{}, checkExistingPolicy)
@ -738,39 +768,37 @@ func (nrc *NetworkRoutingController) addExportPolicies() error {
return errors.New("Failed to verify if kube-router BGP export policy exists: " + err.Error())
}
if !policyAlreadyExists {
err = nrc.bgpServer.AddPolicy(context.Background(), &gobgpapi.AddPolicyRequest{Policy: &definition})
if err != nil {
return errors.New("Failed to add policy: " + err.Error())
}
// If this is the first time this is run and there is no current policy in GoBGP initialize it before sending it off
// to incrementAndCreatePolicy so that the below method doesn't have to carry context about where it is called from
if currentPolicyName == "" {
currentPolicyName = kubeRouterExportPolicy + "0"
klog.Infof("Did not match any existing policies, starting import policy with default name: %s",
currentPolicyName)
}
policyAssignmentExists := false
checkExistingPolicyAssignment := func(existingPolicyAssignment *gobgpapi.PolicyAssignment) {
for _, policy := range existingPolicyAssignment.Policies {
if policy.Name == kubeRouterExportPolicy {
policyAssignmentExists = true
}
}
}
err = nrc.bgpServer.ListPolicyAssignment(context.Background(),
&gobgpapi.ListPolicyAssignmentRequest{Name: "global", Direction: gobgpapi.PolicyDirection_EXPORT},
checkExistingPolicyAssignment)
if err != nil {
return errors.New("Failed to verify if kube-router BGP export policy assignment exists: " + err.Error())
if currentPolicySameAsNewPolicy {
klog.V(1).Infof("Policies in %s are the same, nothing to do here", currentPolicyName)
return nil
}
policyAssignment := gobgpapi.PolicyAssignment{
Name: "global",
Direction: gobgpapi.PolicyDirection_EXPORT,
Policies: []*gobgpapi.Policy{&definition},
DefaultAction: gobgpapi.RouteAction_REJECT,
klog.Infof("Current policy does not appear to match new policy: %s - creating new policy",
newPolicy.Name)
if err = nrc.incrementAndCreatePolicy(currentPolicyName, &newPolicy); err != nil {
return fmt.Errorf("could not increment and create new policy: %v", err)
}
if !policyAssignmentExists {
err = nrc.bgpServer.AddPolicyAssignment(context.Background(),
&gobgpapi.AddPolicyAssignmentRequest{Assignment: &policyAssignment})
klog.Infof("Ensuring that policy %s is assigned", newPolicy.Name)
err = nrc.assignPolicyByName(&newPolicy, gobgpapi.PolicyDirection_EXPORT, gobgpapi.RouteAction_REJECT)
if err != nil {
return errors.New("Failed to add policy assignment: " + err.Error())
return fmt.Errorf("could not assign policy by name: %v", err)
}
if currentPolicyFound {
klog.Infof("Now that new policy %s has been created and assigned, removing previous policy %s",
newPolicy.Name, currentPolicyName)
if err = nrc.unassignAndRemovePolicy(currentPolicyName, gobgpapi.PolicyDirection_EXPORT,
gobgpapi.RouteAction_REJECT); err != nil {
return fmt.Errorf("could not clean up old policy: %v", err)
}
}
@ -781,7 +809,7 @@ func (nrc *NetworkRoutingController) addExportPolicies() error {
// - do not import Service VIPs advertised from any peers, instead each kube-router originates and injects
// Service VIPs into local rib.
func (nrc *NetworkRoutingController) addImportPolicies() error {
statements := make([]*gobgpapi.Statement, 0)
statementNames := make([]string, 0)
actions := gobgpapi.Actions{
RouteAction: gobgpapi.RouteAction_REJECT,
@ -810,7 +838,7 @@ func (nrc *NetworkRoutingController) addImportPolicies() error {
continue
}
statements = append(statements, &gobgpapi.Statement{
statement := gobgpapi.Statement{
Conditions: &gobgpapi.Conditions{
PrefixSet: &gobgpapi.MatchSet{
Type: gobgpapi.MatchSet_ANY,
@ -822,10 +850,15 @@ func (nrc *NetworkRoutingController) addImportPolicies() error {
},
},
Actions: &actions,
})
Name: vipSet + peerSet,
}
if err = nrc.ensureStatementExists(&statement); err != nil {
return fmt.Errorf("could not check or create statement: %s - %v", statement.Name, err)
}
statementNames = append(statementNames, statement.Name)
}
statements = append(statements, &gobgpapi.Statement{
statement := gobgpapi.Statement{
Conditions: &gobgpapi.Conditions{
PrefixSet: &gobgpapi.MatchSet{
Type: gobgpapi.MatchSet_ANY,
@ -837,10 +870,15 @@ func (nrc *NetworkRoutingController) addImportPolicies() error {
},
},
Actions: &actions,
})
Name: defaultRouteSet + peerSet,
}
if err = nrc.ensureStatementExists(&statement); err != nil {
return fmt.Errorf("could not check or create statement: %s - %v", statement.Name, err)
}
statementNames = append(statementNames, statement.Name)
if len(nrc.nodeCustomImportRejectIPNets) > 0 {
statements = append(statements, &gobgpapi.Statement{
statement = gobgpapi.Statement{
Conditions: &gobgpapi.Conditions{
PrefixSet: &gobgpapi.MatchSet{
Name: customImportRejectSet,
@ -852,59 +890,72 @@ func (nrc *NetworkRoutingController) addImportPolicies() error {
},
},
Actions: &actions,
Name: customImportRejectSet + peerSet,
}
if err = nrc.ensureStatementExists(&statement); err != nil {
return fmt.Errorf("could not check or create statement: %s - %v", statement.Name, err)
}
statementNames = append(statementNames, statement.Name)
}
}
newStatementsByName := make([]*gobgpapi.Statement, 0)
for _, st := range statementNames {
newStatementsByName = append(newStatementsByName, &gobgpapi.Statement{
Name: st,
})
}
}
definition := gobgpapi.Policy{
newPolicy := gobgpapi.Policy{
Name: kubeRouterImportPolicy,
Statements: statements,
Statements: newStatementsByName,
}
policyAlreadyExists := false
currentPolicyFound := false
currentPolicyName := ""
currentPolicySameAsNewPolicy := false
checkExistingPolicy := func(existingPolicy *gobgpapi.Policy) {
if existingPolicy.Name == kubeRouterImportPolicy {
policyAlreadyExists = true
if strings.HasPrefix(existingPolicy.Name, kubeRouterImportPolicy) {
currentPolicyFound = true
currentPolicyName = existingPolicy.Name
currentPolicySameAsNewPolicy = statementsEqualByName(existingPolicy.Statements, newPolicy.Statements)
}
}
err := nrc.bgpServer.ListPolicy(context.Background(), &gobgpapi.ListPolicyRequest{}, checkExistingPolicy)
if err != nil {
return errors.New("Failed to verify if kube-router BGP import policy exists: " + err.Error())
return errors.New("Failed to verify if kube-router BGP export policy exists: " + err.Error())
}
if !policyAlreadyExists {
err = nrc.bgpServer.AddPolicy(context.Background(), &gobgpapi.AddPolicyRequest{Policy: &definition})
if err != nil {
return errors.New("Failed to add policy: " + err.Error())
}
// If this is the first time this is run and there is no current policy in GoBGP initialize it before sending it off
// to incrementAndCreatePolicy so that the below method doesn't have to carry context about where it is called from
if currentPolicyName == "" {
currentPolicyName = kubeRouterImportPolicy + "0"
klog.Infof("Did not match any existing policies, starting import policy with default name: %s",
currentPolicyName)
}
policyAssignmentExists := false
checkExistingPolicyAssignment := func(existingPolicyAssignment *gobgpapi.PolicyAssignment) {
for _, policy := range existingPolicyAssignment.Policies {
if policy.Name == kubeRouterImportPolicy {
policyAssignmentExists = true
}
}
}
err = nrc.bgpServer.ListPolicyAssignment(context.Background(),
&gobgpapi.ListPolicyAssignmentRequest{Name: "global", Direction: gobgpapi.PolicyDirection_IMPORT},
checkExistingPolicyAssignment)
if err != nil {
return errors.New("Failed to verify if kube-router BGP import policy assignment exists: " + err.Error())
if currentPolicySameAsNewPolicy {
klog.V(1).Infof("Policies in %s are the same, nothing to do here", currentPolicyName)
return nil
}
policyAssignment := gobgpapi.PolicyAssignment{
Name: "global",
Direction: gobgpapi.PolicyDirection_IMPORT,
Policies: []*gobgpapi.Policy{&definition},
DefaultAction: gobgpapi.RouteAction_ACCEPT,
klog.Infof("Current policy does not appear to match new policy: %s - creating new policy",
newPolicy.Name)
if err = nrc.incrementAndCreatePolicy(currentPolicyName, &newPolicy); err != nil {
return fmt.Errorf("could not increment and create new policy: %v", err)
}
if !policyAssignmentExists {
err = nrc.bgpServer.AddPolicyAssignment(context.Background(),
&gobgpapi.AddPolicyAssignmentRequest{Assignment: &policyAssignment})
klog.Infof("Ensuring that policy %s is assigned", newPolicy.Name)
err = nrc.assignPolicyByName(&newPolicy, gobgpapi.PolicyDirection_IMPORT, gobgpapi.RouteAction_ACCEPT)
if err != nil {
return errors.New("Failed to add policy assignment: " + err.Error())
return fmt.Errorf("could not assign policy by name: %v", err)
}
if currentPolicyFound {
klog.Infof("Now that new policy %s has been created and assigned, removing previous policy %s",
newPolicy.Name, currentPolicyName)
if err = nrc.unassignAndRemovePolicy(currentPolicyName, gobgpapi.PolicyDirection_IMPORT,
gobgpapi.RouteAction_ACCEPT); err != nil {
return fmt.Errorf("could not clean up old policy: %v", err)
}
}
@ -947,3 +998,140 @@ func (nrc *NetworkRoutingController) emptyCheckDefinedSets(defSets []gobgpapi.Li
}
return false, nil
}
// ensureStatementExists checks to see if a statement already exists by looking for its name. If it already exists,
// method is a noop, if it does not exist, then we make sure to create it.
//
// NOTE: the checking in this method is done only by name. For now this works well because we don't change how
//
// statements are formulated dynamically. If this changes in the future, then this method will need to be changed
func (nrc *NetworkRoutingController) ensureStatementExists(st *gobgpapi.Statement) error {
found := false
err := nrc.bgpServer.ListStatement(context.Background(), &gobgpapi.ListStatementRequest{},
func(statement *gobgpapi.Statement) {
if statement.Name == st.Name {
found = true
}
})
if err != nil {
return fmt.Errorf("could not list statements: %v", err)
}
if found {
return nil
}
err = nrc.bgpServer.AddStatement(context.Background(), &gobgpapi.AddStatementRequest{
Statement: st,
})
if err != nil {
return fmt.Errorf("could not add statement: %v", err)
}
return nil
}
func (nrc *NetworkRoutingController) incrementAndCreatePolicy(curPolName string,
newPolicy *gobgpapi.Policy) error {
// Get the current policy version and increment it
polVer := 0
polBaseName := ""
var err error
// sanity check
if curPolName == "" {
return fmt.Errorf("we require that curPolName be non-blank before calling this method")
}
matches := rePolicyVersionExtractor.FindStringSubmatch(curPolName)
switch len(matches) {
case 2:
polBaseName = matches[1]
case 3:
polBaseName = matches[1]
if polVer, err = strconv.Atoi(matches[2]); err != nil {
return fmt.Errorf("failed to parse %s GoBGP policy name: %v", curPolName, err)
}
default:
return fmt.Errorf("failed to parse %s GoBGP policy name via regex", curPolName)
}
newPolicyName := polBaseName + strconv.Itoa(polVer+1)
newPolicy.Name = newPolicyName
err = nrc.bgpServer.AddPolicy(context.Background(), &gobgpapi.AddPolicyRequest{
Policy: newPolicy,
ReferExistingStatements: true,
})
if err != nil {
return errors.New("Failed to add policy: " + err.Error())
}
return nil
}
func (nrc *NetworkRoutingController) assignPolicyByName(newPolicy *gobgpapi.Policy,
polDir gobgpapi.PolicyDirection, defaultAct gobgpapi.RouteAction) error {
policyAssignmentExists := false
// check to see if the policy is already assigned
checkExistingPolicyAssignment := func(existingPolicyAssignment *gobgpapi.PolicyAssignment) {
for _, policy := range existingPolicyAssignment.Policies {
if policy.Name == newPolicy.Name {
policyAssignmentExists = true
}
}
}
err := nrc.bgpServer.ListPolicyAssignment(context.Background(),
&gobgpapi.ListPolicyAssignmentRequest{Name: "global", Direction: polDir},
checkExistingPolicyAssignment)
if err != nil {
return errors.New("Failed to verify if kube-router BGP export policy assignment exists: " + err.Error())
}
if policyAssignmentExists {
return nil
}
// policy is not assigned, assign it
policyAssignment := gobgpapi.PolicyAssignment{
Name: "global",
Direction: polDir,
Policies: []*gobgpapi.Policy{newPolicy},
DefaultAction: defaultAct,
}
err = nrc.bgpServer.AddPolicyAssignment(context.Background(),
&gobgpapi.AddPolicyAssignmentRequest{Assignment: &policyAssignment})
if err != nil {
return errors.New("Failed to add policy assignment: " + err.Error())
}
return nil
}
func (nrc *NetworkRoutingController) unassignAndRemovePolicy(policyName string,
polDir gobgpapi.PolicyDirection, defaultAct gobgpapi.RouteAction) error {
err := nrc.bgpServer.DeletePolicyAssignment(context.Background(), &gobgpapi.DeletePolicyAssignmentRequest{
Assignment: &gobgpapi.PolicyAssignment{
Name: "global",
Direction: polDir,
Policies: []*gobgpapi.Policy{
{
Name: policyName,
},
},
DefaultAction: defaultAct,
},
})
if err != nil {
return fmt.Errorf("could not delete policy assignment for: %s - %v", policyName, err)
}
err = nrc.bgpServer.DeletePolicy(context.Background(), &gobgpapi.DeletePolicyRequest{
Policy: &gobgpapi.Policy{Name: policyName},
PreserveStatements: true,
All: true, // All here tells GoBGP to delete the policy instead of just clearing the statements
})
if err != nil {
return fmt.Errorf("could not delete policy for: %s - %v", policyName, err)
}
return nil
}

4
pkg/controllers/routing/bgp_policies_test.go
View File

@ -1431,7 +1431,7 @@ func checkPolicies(t *testing.T, testcase PolicyTestCase, gobgpDirection gobgpap
}
err := testcase.nrc.bgpServer.ListPolicy(context.Background(), &gobgpapi.ListPolicyRequest{}, func(policy *gobgpapi.Policy) {
if policy.Name == "kube_router_"+direction {
if policy.Name == "kube_router_"+direction+"1" {
policyExists = true
}
})
@ -1446,7 +1446,7 @@ func checkPolicies(t *testing.T, testcase PolicyTestCase, gobgpDirection gobgpap
err = testcase.nrc.bgpServer.ListPolicyAssignment(context.Background(), &gobgpapi.ListPolicyAssignmentRequest{}, func(policyAssignment *gobgpapi.PolicyAssignment) {
if policyAssignment.Name == "global" && policyAssignment.Direction == gobgpDirection {
for _, policy := range policyAssignment.Policies {
if policy.Name == "kube_router_"+direction {
if policy.Name == "kube_router_"+direction+"1" {
policyAssignmentExists = true
}
}

31
pkg/controllers/routing/utils.go
View File

@ -86,6 +86,37 @@ func stringSliceB64Decode(s []string) ([]string, error) {
return ss, nil
}
func statementsEqualByName(a, b []*gobgpapi.Statement) bool {
// First a is in the outer loop ensuring that all members of a are in b
for _, st1 := range a {
st1Found := false
for _, st2 := range b {
if st1.Name == st2.Name {
st1Found = true
}
}
if !st1Found {
return false
}
}
// Second b is in the outer loop ensuring that all members of b are in a
for _, st1 := range b {
st1Found := false
for _, st2 := range a {
if st1.Name == st2.Name {
st1Found = true
}
}
if !st1Found {
return false
}
}
// If we've made it through both loops then we know that the statements arrays are equal
return true
}
func getNodeSubnet(nodeIP net.IP) (net.IPNet, string, error) {
links, err := netlink.LinkList()
if err != nil {