Feature Gates

Reference

This page contains an overview of the various feature gates an administrator can specify on etcd.

See feature stages for an explanation of the stages for a feature.

Overview

Feature gates are a set of key=value pairs that describe etcd features. You can turn these features on or off using the --feature-gates command line flag on etcd.

etcd lets you enable or disable a set of feature gates. Use -h flag to see a full set of feature gates. To set feature gates, use the --feature-gates flag assigned to a list of feature pairs in commandline:

--feature-gates=...,StopGRPCServiceOnDefrag=true

Or specify feature-gates in YAML config file:

feature-gates: ...,StopGRPCServiceOnDefrag=true

Change in `embed.EtcdServer` struct

In 3.6, field ServerFeatureGate is added to embed.Config, and should be replacing the experimental fields listed below:

package embed

type Config struct {
  // Deprecated: Use CompactHashCheck Feature Gate instead. Will be decommissioned in v3.7.
  ExperimentalCompactHashCheckEnabled bool `json:"experimental-compact-hash-check-enabled"`

  // Deprecated: Use InitialCorruptCheck Feature Gate instead. Will be decommissioned in v3.7.
  ExperimentalInitialCorruptCheck bool `json:"experimental-initial-corrupt-check"`

  // Deprecated: Use TxnModeWriteWithSharedBuffer Feature Gate instead. Will be decommissioned in v3.7.
  ExperimentalTxnModeWriteWithSharedBuffer bool `json:"experimental-txn-mode-write-with-shared-buffer"`

  // Deprecated: Use StopGRPCServiceOnDefrag Feature Gate instead. Will be decommissioned in v3.7.
  ExperimentalStopGRPCServiceOnDefrag bool `json:"experimental-stop-grpc-service-on-defrag"`

  // Deprecated: Use LeaseCheckpoint Feature Gate instead. Will be decommissioned in v3.7.
  ExperimentalEnableLeaseCheckpoint bool `json:"experimental-enable-lease-checkpoint"`
  
  // Deprecated: Use LeaseCheckpointPersist Feature Gate instead. Will be decommissioned in v3.7.
  ExperimentalEnableLeaseCheckpointPersist bool `json:"experimental-enable-lease-checkpoint-persist"`

+ // ServerFeatureGate is a server level feature gate
+ ServerFeatureGate featuregate.FeatureGate
  ...

Feature gates for Alpha or Beta features

The following tables are a summary of the feature gates that you can set on etcd.

Feature	Default	Stage	Details
CompactHashCheck	false	Alpha	Enables to check data corruption before serving any client/peer traffic.
InitialCorruptCheck	false	Alpha	Enables leader to periodically check followers compaction hashes.
LeaseCheckpoint	false	Alpha	Enables leader to send regular checkpoints to other members to prevent reset of remaining TTL on leader change.
LeaseCheckpointPersist	false	Alpha	Enables persisting remainingTTL to prevent indefinite auto-renewal of long lived leases.
SetMemberLocalAddr	false	Alpha	Enables using the first specified and non-loopback local address from initial-advertise-peer-urls as the local address when communicating with a peer.
StopGRPCServiceOnDefrag	false	Alpha	Enables etcd gRPC service to stop serving client requests on defragmentation.
TxnModeWriteWithSharedBuffer	true	Beta	Enables the write transaction to use a shared buffer in its readonly check operations.

Using a feature

Feature stages

A feature can be in Alpha, Beta, GA or Deprecated stage. An Alpha feature means:

Disabled by default.
Might be buggy. Enabling the feature may expose bugs.
Support for feature may be dropped at any time without notice.
The API may change in incompatible ways in a later software release without notice.
Recommended for use only in short-lived testing clusters, due to increased risk of bugs and lack of long-term support.

A Beta feature means:

Enabled by default.
The feature is well tested. Enabling the feature is considered safe.
Support for the overall feature will not be dropped, though details may change.
Recommended for only non-business-critical uses because of potential for discovering new hard-to-spot bugs through wider adoption.

Note

Please do try Beta features and give feedback on them! After they exit beta, it may not be practical for us to make more changes.

A General Availability (GA) feature is also referred to as a stable feature. It means:

The feature is always enabled; you cannot disable it.
The corresponding feature gate is no longer needed.
Stable versions of features will appear in released software for many subsequent versions.

A Deprecated feature means:

The feature gate is no longer in use.
The feature has graduated to GA or been removed.