etcd/CHANGELOG-3.4.md

v3.4.0 (TBD 2018-05-01)

See code changes and v3.4 upgrade guide for any breaking changes.

Improved

• Compile with Go 1.10+.
• Add jitter to watch progress notify to prevent spikes in etcd_network_client_grpc_sent_bytes_total.
• Add warnings on requests taking too long.
  • e.g. etcdserver: read-only range request "key:\"\\000\" range_end:\"\\000\" " took too long [3.389041388s] to execute
• Improve long-running concurrent read transactions under light write workloads.
  • Previously, periodic commit on pending writes blocks incoming read transactions, even if there is no pending write.
  • Now, periodic commit operation does not block concurrent read transactions, thus improves long-running read transaction performance.
• Adjust election timeout on server restart to reduce disruptive rejoining servers.
  • Previously, etcd fast-forwards election ticks on server start, with only one tick left for leader election. This is to speed up start phase, without having to wait until all election ticks elapse. Advancing election ticks is useful for cross datacenter deployments with larger election timeouts. However, it was affecting cluster availability if the last tick elapses before leader contacts the restarted node.
  • Now, when etcd restarts, it adjusts election ticks with more than one tick left, thus more time for leader to prevent disruptive restart.
• Add Raft Pre-Vote feature to reduce disruptive rejoining servers.
  • For instance, a flaky(or rejoining) member may drop in and out, and start campaign. This member will end up with a higher term, and ignore all incoming messages with lower term. In this case, a new leader eventually need to get elected, thus disruptive to cluster availability. Raft implements Pre-Vote phase to prevent this kind of disruptions. If enabled, Raft runs an additional phase of election to check if pre-candidate can get enough votes to win an election.
• Make Lease Lookup non-blocking with concurrent Grant/Revoke.

Breaking Changes

• Drop ACIs from official release.
  • AppC was officially suspended, as of late 2016.
  • acbuild is not maintained anymore.
  • *.aci files are not available from v3.4 release.
• Exit on empty hosts in advertise URLs.
  • Address advertise client URLs accepts empty hosts.
  • e.g. exit with error on --advertise-client-urls=http://:2379.
  • e.g. exit with error on --initial-advertise-peer-urls=http://:2380.
• Exit on shadowed environment variables.
  • Address error on shadowed environment variables.
  • e.g. exit with error on ETCD_NAME=abc etcd --name=def.
  • e.g. exit with error on ETCD_INITIAL_CLUSTER_TOKEN=abc etcd --initial-cluster-token=def.
  • e.g. exit with error on ETCDCTL_ENDPOINTS=abc.com ETCDCTL_API=3 etcdctl endpoint health --endpoints=def.com.
• Move "github.com/coreos/etcd/snap" to "github.com/coreos/etcd/raftsnap".
• Move "github.com/coreos/etcd/etcdserver/auth" to "github.com/coreos/etcd/etcdserver/v2auth".
• Move "github.com/coreos/etcd/error" to "github.com/coreos/etcd/etcdserver/v2error".
• Move "github.com/coreos/etcd/store" to "github.com/coreos/etcd/etcdserver/v2store".
• Change v3 etcdctl snapshot exit codes with snapshot package.
  • Exit on error with exit code 1 (no more exit code 5 or 6 on snapshot save/restore commands).
• Require Go 1.10+.
• Migrate dependency management tool from glide to golang/dep.
  • <= 3.3 puts vendor directory under cmd/vendor directory to prevent conflicting transitive dependencies.
  • 3.4 moves cmd/vendor directory to vendor at repository root.
  • Remove recursive symlinks in cmd directory.
  • Now go get/install/build on etcd packages (e.g. clientv3, tools/benchmark) enforce builds with etcd vendor directory.

Added: etcd

• Add --discovery-srv-name flag to support custom DNS SRV name with discovery.
  • If not given, etcd queries _etcd-server-ssl._tcp.[YOUR_HOST] and _etcd-server._tcp.[YOUR_HOST].
  • If --discovery-srv-name="foo", then query _etcd-server-ssl-foo._tcp.[YOUR_HOST] and _etcd-server-foo._tcp.[YOUR_HOST].
  • Useful for operating multiple etcd clusters under the same domain.
• Define embed.CompactorModePeriodic for compactor.ModePeriodic.
• Define embed.CompactorModeRevision for compactor.ModeRevision.

Security, Authentication

• Add --host-whitelist flag, etcdserver.Config.HostWhitelist, and embed.Config.HostWhitelist, to prevent "DNS Rebinding" attack.
  • Any website can simply create an authorized DNS name, and direct DNS to "localhost" (or any other address). Then, all HTTP endpoints of etcd server listening on "localhost" becomes accessible, thus vulnerable to DNS rebinding attacks (CVE-2018-5702).
  • Client origin enforce policy works as follow:
    • If client connection is secure via HTTPS, allow any hostnames..
    • If client connection is not secure and "HostWhitelist" is not empty, only allow HTTP requests whose Host field is listed in whitelist.
  • By default, "HostWhitelist" is empty, which means insecure server allows all client HTTP requests.
  • Note that the client origin policy is enforced whether authentication is enabled or not, for tighter controls.
  • When specifying hostnames, loopback addresses are not added automatically. To allow loopback interfaces, add them to whitelist manually (e.g. "localhost", "127.0.0.1", etc.).
  • e.g. etcd --host-whitelist example.com, then the server will reject all HTTP requests whose Host field is not example.com (also rejects requests to "localhost").
• Support ttl field for etcd Authentication JWT token.
  • e.g. etcd --auth-token jwt,pub-key=<pub key path>,priv-key=<priv key path>,sign-method=<sign method>,ttl=5m.
• Allow empty token provider in etcdserver.ServerConfig.AuthToken.

Added: API

• Add snapshot package for snapshot restore/save operations.
• Add watch_id field to etcdserverpb.WatchCreateRequest, allow user-provided watch ID to mvcc.
  • Corresponding watch_id is returned via etcdserverpb.WatchResponse, if any.
• Add raftAppliedIndex field to etcdserverpb.StatusResponse for current Raft applied index.
• Add errors field to etcdserverpb.StatusResponse for server-side error.
  • e.g. "etcdserver: no leader", "NOSPACE", "CORRUPT"
• Add dbSizeInUse field to etcdserverpb.StatusResponse for actual DB size after compaction.

Added: v3 etcdctl

• Add check datascale command.
• Add check datascale --auto-compact, --auto-defrag flags.
• Add check perf --auto-compact, --auto-defrag flags.
• Add defrag --cluster flag.
• Add "raft applied index" field to endpoint status.
• Add "errors" field to endpoint status.

Added: metrics

• Add etcd_debugging_mvcc_db_total_size_in_use_in_bytes Prometheus metric.

Added: gRPC gateway

• Replace gRPC gateway endpoint with /v3.
  • To deprecate /v3beta in v3.5.

Package raft

• Fix deadlock during PreVote migration process.
• Add raft.ErrProposalDropped.
  • Now (r *raft) Step returns raft.ErrProposalDropped if a proposal has been ignored.
  • e.g. a node is removed from cluster, ongoing leadership transfer, etc.
• Improve Raft becomeLeader and stepLeader by keeping track of latest pb.EntryConfChange index.
  • Previously record pendingConf boolean field scanning the entire tail of the log, which can delay hearbeat send.
• Fix missing learner nodes on (n *node) ApplyConfChange.

Fixed: v3

• Fix mvcc "unsynced" watcher restore operation.
  • "unsynced" watcher is watcher that needs to be in sync with events that have happened.
  • That is, "unsynced" watcher is the slow watcher that was requested on old revision.
  • "unsynced" watcher restore operation was not correctly populating its underlying watcher group.
  • Which possibly causes missing events from "unsynced" watchers.
• Fix server panic on invalid Election Proclaim/Resign HTTP(S) requests.
  • Previously, wrong-formatted HTTP requests to Election API could trigger panic in etcd server.
  • e.g. curl -L http://localhost:2379/v3/election/proclaim -X POST -d '{"value":""}', curl -L http://localhost:2379/v3/election/resign -X POST -d '{"value":""}'.
• Fix revision-based compaction retention parsing.
  • Previously, etcd --auto-compaction-mode revision --auto-compaction-retention 1 was translated to revision retention 3600000000000.
  • Now, etcd --auto-compaction-mode revision --auto-compaction-retention 1 is correctly parsed as revision retention 1.
• Prevent overflow by large TTL values for Lease Grant.
  • TTL parameter to Grant request is unit of second.
  • Leases with too large TTL values exceeding math.MaxInt64 expire in unexpected ways.
  • Server now returns rpctypes.ErrLeaseTTLTooLarge to client, when the requested TTL is larger than 9,000,000,000 seconds (which is >285 years).
  • Again, etcd Lease is meant for short-periodic keepalives or sessions, in the range of seconds or minutes. Not for hours or days!
• Enable etcd server raft.Config.CheckQuorum when starting with ForceNewCluster.