open-consul/agent/submatview/local_materializer.go
Daniel Upton 1cd7ec0543 proxycfg: terminate stream on irrecoverable errors
This is the OSS portion of enterprise PR 2339.

It improves our handling of "irrecoverable" errors in proxycfg data sources.

The canonical example of this is what happens when the ACL token presented by
Envoy is deleted/revoked. Previously, the stream would get "stuck" until the
xDS server re-checked the token (after 5 minutes) and terminated the stream.

Materializers would also sit burning resources retrying something that could
never succeed.

Now, it is possible for data sources to mark errors as "terminal" which causes
the xDS stream to be closed immediately. Similarly, the submatview.Store will
evict materializers when it observes they have encountered such an error.
2022-08-23 20:17:49 +01:00

148 lines
3.6 KiB
Go

package submatview
import (
"context"
"errors"
"github.com/hashicorp/consul/acl"
"github.com/hashicorp/consul/acl/resolver"
"github.com/hashicorp/consul/agent/consul/state"
"github.com/hashicorp/consul/agent/consul/stream"
"github.com/hashicorp/consul/lib/retry"
"github.com/hashicorp/consul/proto/pbsubscribe"
)
// LocalMaterializer is a materializer for a stream of events
// and manages the local subscription to the event publisher
// until the cache result is discarded when its TTL expires.
type LocalMaterializer struct {
deps LocalMaterializerDeps
retryWaiter *retry.Waiter
handler eventHandler
mat *materializer
}
type LocalMaterializerDeps struct {
Deps
Backend LocalBackend
ACLResolver ACLResolver
}
var _ Materializer = (*LocalMaterializer)(nil)
type LocalBackend interface {
Subscribe(req *stream.SubscribeRequest) (*stream.Subscription, error)
}
//go:generate mockery --name ACLResolver --inpackage
type ACLResolver interface {
ResolveTokenAndDefaultMeta(token string, entMeta *acl.EnterpriseMeta, authzContext *acl.AuthorizerContext) (resolver.Result, error)
}
func NewLocalMaterializer(deps LocalMaterializerDeps) *LocalMaterializer {
m := LocalMaterializer{
deps: deps,
mat: newMaterializer(deps.Logger, deps.View, deps.Waiter),
}
return &m
}
// Query implements Materializer
func (m *LocalMaterializer) Query(ctx context.Context, minIndex uint64) (Result, error) {
return m.mat.query(ctx, minIndex)
}
// Run receives events from a local subscription backend and sends them to the View.
// It runs until ctx is cancelled, so it is expected to be run in a goroutine.
// Mirrors implementation of RPCMaterializer.
//
// Run implements Materializer
func (m *LocalMaterializer) Run(ctx context.Context) {
for {
req := m.deps.Request(m.mat.currentIndex())
err := m.subscribeOnce(ctx, req)
if ctx.Err() != nil {
return
}
if m.isTerminalError(err) {
return
}
m.mat.handleError(req, err)
if err := m.mat.retryWaiter.Wait(ctx); err != nil {
return
}
}
}
// isTerminalError determines whether the given error cannot be recovered from
// and should cause the materializer to halt and be evicted from the view store.
//
// This roughly matches the logic in agent/proxycfg-glue.newUpdateEvent.
func (m *LocalMaterializer) isTerminalError(err error) bool {
return acl.IsErrNotFound(err)
}
// subscribeOnce opens a new subscription to a local backend and runs
// for its lifetime or until the view is closed.
func (m *LocalMaterializer) subscribeOnce(ctx context.Context, req *pbsubscribe.SubscribeRequest) error {
ctx, cancel := context.WithCancel(ctx)
defer cancel()
m.handler = initialHandler(req.Index)
entMeta := req.EnterpriseMeta()
authz, err := m.deps.ACLResolver.ResolveTokenAndDefaultMeta(req.Token, &entMeta, nil)
if err != nil {
return err
}
subReq, err := state.PBToStreamSubscribeRequest(req, entMeta)
if err != nil {
return err
}
sub, err := m.deps.Backend.Subscribe(subReq)
if err != nil {
return err
}
defer sub.Unsubscribe()
for {
event, err := sub.Next(ctx)
switch {
case errors.Is(err, stream.ErrSubForceClosed):
m.deps.Logger.Trace("subscription reset by server")
return err
case err != nil:
return err
}
if !event.Payload.HasReadPermission(authz) {
continue
}
e := event.Payload.ToSubscriptionEvent(event.Index)
m.handler, err = m.handler(m, e)
if err != nil {
m.mat.reset()
return err
}
}
}
// updateView implements viewState
func (m *LocalMaterializer) updateView(events []*pbsubscribe.Event, index uint64) error {
return m.mat.updateView(events, index)
}
// reset implements viewState
func (m *LocalMaterializer) reset() {
m.mat.reset()
}