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Lock bootstrap data with empty key to prevent conflicts

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Signed-off-by: Brad Davidson <brad.davidson@rancher.com>
pull/7256/head
Brad Davidson 2 years ago committed by Brad Davidson
parent 12091fc724
commit d95980bba3
3 changed files with 106 additions and 51 deletions
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34
pkg/cluster/bootstrap.go
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@ -273,31 +273,17 @@ func (c *Cluster) ReconcileBootstrapData(ctx context.Context, buf io.ReadSeeker,
}
defer storageClient.Close()
ticker := time.NewTicker(5 * time.Second)
defer ticker.Stop()
RETRY:
for {
value, c.saveBootstrap, err = getBootstrapKeyFromStorage(ctx, storageClient, normalizedToken, token)
if err != nil {
if strings.Contains(err.Error(), "not supported for learner") {
for range ticker.C {
continue RETRY
}
}
return err
}
if value == nil {
return nil
}
dbRawData, err = decrypt(normalizedToken, value.Data)
if err != nil {
return err
}
value, c.saveBootstrap, err = getBootstrapKeyFromStorage(ctx, storageClient, normalizedToken, token)
if err != nil {
return err
}
if value == nil {
return nil
}
break
dbRawData, err = decrypt(normalizedToken, value.Data)
if err != nil {
return err
}
buf = bytes.NewReader(dbRawData)

121
pkg/cluster/storage.go
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@ -6,20 +6,27 @@ import (
"errors"
"os"
"path/filepath"
"strings"
"time"
"github.com/k3s-io/k3s/pkg/bootstrap"
"github.com/k3s-io/k3s/pkg/clientaccess"
"github.com/k3s-io/k3s/pkg/daemons/config"
"github.com/k3s-io/kine/pkg/client"
"github.com/sirupsen/logrus"
"go.etcd.io/etcd/api/v3/v3rpc/rpctypes"
"k8s.io/apimachinery/pkg/util/wait"
)
// maxBootstrapWaitAttempts is the number of iterations to wait for another node to populate an empty bootstrap key.
// After this many attempts, the lock is deleted and the counter reset.
const maxBootstrapWaitAttempts = 5
// Save writes the current ControlRuntimeBootstrap data to the datastore. This contains a complete
// snapshot of the cluster's CA certs and keys, encryption passphrases, etc - encrypted with the join token.
// This is used when bootstrapping a cluster from a managed database or external etcd cluster.
// This is NOT used with embedded etcd, which bootstraps over HTTP.
func Save(ctx context.Context, config *config.Control, override bool) error {
logrus.Info("Saving cluster bootstrap data to datastore")
buf := &bytes.Buffer{}
if err := bootstrap.ReadFromDisk(buf, &config.Runtime.ControlRuntimeBootstrap); err != nil {
return err
@ -48,13 +55,19 @@ func Save(ctx context.Context, config *config.Control, override bool) error {
}
defer storageClient.Close()
if _, _, err = getBootstrapKeyFromStorage(ctx, storageClient, normalizedToken, token); err != nil {
currentKey, _, err := getBootstrapKeyFromStorage(ctx, storageClient, normalizedToken, token)
if err != nil {
return err
}
// If there's an empty bootstrap key, then we've locked it and can override.
if currentKey != nil && len(currentKey.Data) == 0 {
logrus.Info("Bootstrap key lock is held")
override = true
}
if err := storageClient.Create(ctx, storageKey(normalizedToken), data); err != nil {
if err.Error() == "key exists" {
logrus.Warn("bootstrap key already exists")
if override {
bsd, err := bootstrapKeyData(ctx, storageClient)
if err != nil {
@ -62,9 +75,10 @@ func Save(ctx context.Context, config *config.Control, override bool) error {
}
return storageClient.Update(ctx, storageKey(normalizedToken), bsd.Modified, data)
}
logrus.Warn("Bootstrap key already exists")
return nil
} else if strings.Contains(err.Error(), "not supported for learner") {
logrus.Debug("skipping bootstrap data save on learner")
} else if errors.Is(err, rpctypes.ErrGPRCNotSupportedForLearner) {
logrus.Debug("Skipping bootstrap data save on learner")
return nil
}
return err
@ -89,9 +103,12 @@ func bootstrapKeyData(ctx context.Context, storageClient client.Client) (*client
return &bootstrapList[0], nil
}
// storageBootstrap loads data from the datastore into the ControlRuntimeBootstrap struct.
// The storage key and encryption passphrase are both derived from the join token.
// token is either passed.
// storageBootstrap loads data from the datastore's bootstrap key into the
// ControlRuntimeBootstrap struct. The storage key and encryption passphrase are both derived
// from the join token. If no bootstrap key exists, indicating that data needs to be written
// back to the datastore, this function will set c.saveBootstrap to true and create an empty
// bootstrap key as a lock. This function will not return successfully until either the
// bootstrap key has been locked, or data is read into the struct.
func (c *Cluster) storageBootstrap(ctx context.Context) error {
if err := c.startStorage(ctx); err != nil {
return err
@ -110,7 +127,12 @@ func (c *Cluster) storageBootstrap(ctx context.Context) error {
return err
}
if tokenFromFile == "" {
// at this point this is a fresh start in a non managed environment
// No token on disk or from CLI, but we don't know if there's data in the datastore.
// Return here and generate new CA certs and tokens. Note that startup will fail
// later when saving to the datastore if there's already a bootstrap key - but
// that's AFTER generating CA certs and tokens. If the config is updated to set the
// matching key, further startups will still be blocked pending cleanup of the
// "newer" files as per the bootstrap reconciliation code.
c.saveBootstrap = true
return nil
}
@ -121,34 +143,81 @@ func (c *Cluster) storageBootstrap(ctx context.Context) error {
return err
}
value, saveBootstrap, err := getBootstrapKeyFromStorage(ctx, storageClient, normalizedToken, token)
c.saveBootstrap = saveBootstrap
if err != nil {
return err
}
if value == nil {
return nil
}
attempts := 0
tokenKey := storageKey(normalizedToken)
return wait.PollImmediateUntilWithContext(ctx, time.Second, func(ctx context.Context) (bool, error) {
attempts++
value, saveBootstrap, err := getBootstrapKeyFromStorage(ctx, storageClient, normalizedToken, token)
c.saveBootstrap = saveBootstrap
if err != nil {
return false, err
}
data, err := decrypt(normalizedToken, value.Data)
if err != nil {
return err
}
if value == nil {
// No bootstrap keys found in the datastore - create an empty bootstrap key as a lock to
// ensure that no other node races us to populate it. If we fail to create the key, then
// some other node beat us to it and we should just wait for them to finish.
if err := storageClient.Create(ctx, tokenKey, []byte{}); err != nil {
if err.Error() == "key exists" {
logrus.Info("Bootstrap key already locked - waiting for data to be populated by another server")
return false, nil
}
return false, err
}
logrus.Info("Bootstrap key locked for initial create")
return true, nil
}
if len(value.Data) == 0 {
// Empty (locked) bootstrap key found - check to see if we should continue waiting, or
// delete it and attempt to retake the lock on the next iteration (assuming that the
// other node failed while holding the lock).
if attempts >= maxBootstrapWaitAttempts {
logrus.Info("Bootstrap key lock timed out - deleting lock and retrying")
attempts = 0
if err := storageClient.Delete(ctx, tokenKey, value.Modified); err != nil {
return false, err
}
} else {
logrus.Infof("Bootstrap key is locked - waiting for data to be populated by another server")
}
return false, nil
}
data, err := decrypt(normalizedToken, value.Data)
if err != nil {
return false, err
}
return c.ReconcileBootstrapData(ctx, bytes.NewReader(data), &c.config.Runtime.ControlRuntimeBootstrap, false)
return true, c.ReconcileBootstrapData(ctx, bytes.NewReader(data), &c.config.Runtime.ControlRuntimeBootstrap, false)
})
}
// getBootstrapKeyFromStorage will list all keys that has prefix /bootstrap and will check for key that is
// hashed with empty string and will check for any key that is hashed by different token than the one
// passed to it, it will return error if it finds a key that is hashed with different token and will return
// value if it finds the key hashed by passed token or empty string
// value if it finds the key hashed by passed token or empty string.
// Upon receiving a "not supported for learner" error from etcd, this function will retry until the context is cancelled.
func getBootstrapKeyFromStorage(ctx context.Context, storageClient client.Client, normalizedToken, oldToken string) (*client.Value, bool, error) {
emptyStringKey := storageKey("")
tokenKey := storageKey(normalizedToken)
bootstrapList, err := storageClient.List(ctx, "/bootstrap", 0)
if err != nil {
var bootstrapList []client.Value
var err error
if err := wait.PollImmediateUntilWithContext(ctx, 5*time.Second, func(ctx context.Context) (bool, error) {
bootstrapList, err = storageClient.List(ctx, "/bootstrap", 0)
if err != nil {
if errors.Is(err, rpctypes.ErrGPRCNotSupportedForLearner) {
return false, nil
}
return false, err
}
return true, nil
}); err != nil {
return nil, false, err
}
if len(bootstrapList) == 0 {
return nil, true, nil
}
@ -248,7 +317,7 @@ func doMigrateToken(ctx context.Context, storageClient client.Client, keyValue c
if err := storageClient.Create(ctx, newTokenKey, encryptedData); err != nil {
if err.Error() == "key exists" {
logrus.Warn("bootstrap key exists")
} else if strings.Contains(err.Error(), "not supported for learner") {
} else if errors.Is(err, rpctypes.ErrGPRCNotSupportedForLearner) {
logrus.Debug("skipping bootstrap data save on learner")
return nil
} else {

2
pkg/etcd/etcd.go
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@ -951,7 +951,7 @@ func (e *ETCD) RemovePeer(ctx context.Context, name, address string, allowSelfRe
}
logrus.Infof("Removing name=%s id=%d address=%s from etcd", member.Name, member.ID, address)
_, err := e.client.MemberRemove(ctx, member.ID)
if err == rpctypes.ErrGRPCMemberNotFound {
if errors.Is(err, rpctypes.ErrGRPCMemberNotFound) {
return nil
}
return err

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