server

The largest module — everything the etcd binary does. Source: server/.

Scope

go.etcd.io/etcd/server/v3 packages the cluster member, including:

• Flag parsing and process bootstrap (etcdmain/, embed/, config/).
• Core server logic (etcdserver/).
• Storage stack (storage/).
• Auth and lease subsystems (auth/, lease/).
• gRPC and HTTP surfaces (etcdserver/api/v3rpc/, etcdserver/api/etcdhttp/).
• Peer transport (etcdserver/api/rafthttp/).
• Stateless modes (etcdmain/gateway.go, etcdmain/grpc_proxy.go, proxy/).
• Feature-gate definitions (features/).
• Verifier helpers (verify/).

For deep dives into individual components, see systems/.

Subpackage map

Path	One-liner
server/main.go	Process entry; calls etcdmain.Main.
server/etcdmain/	Flag parsing, mode selection (server/gateway/grpc-proxy), help text.
server/embed/	Library form of etcd; embed.Etcd, embed.Config.
server/etcdserver/	EtcdServer, raft loop, apply pipeline, txn engine, version manager.
server/etcdserver/api/	All RPC and HTTP surfaces, plus snapshot store, membership, discovery, alarms.
server/etcdserver/api/v3rpc/	gRPC service implementations.
server/etcdserver/api/etcdhttp/	/health, /metrics, /version, debug, peer health/version.
server/etcdserver/api/rafthttp/	HTTP-based Raft transport.
server/etcdserver/api/snap/	Snapshot file store.
server/etcdserver/api/membership/	Cluster member registry, learner promotion.
server/etcdserver/api/v3compactor/	Periodic + revision-based compaction.
server/etcdserver/api/v3discovery/	Discovery v3 client.
server/etcdserver/api/v3alarm/	NOSPACE / CORRUPT alarm management.
server/etcdserver/api/v3client/	In-process client used by v3election / v3lock.
server/etcdserver/api/v3election/	Election service (gRPC).
server/etcdserver/api/v3lock/	Distributed lock service (gRPC).
server/etcdserver/apply/	Apply uberApplier and per-op handlers.
server/etcdserver/cindex/	Consistent-index tracker (last-applied).
server/etcdserver/errors/	Sentinel server-side errors.
server/etcdserver/read/	Read-index helpers.
server/etcdserver/txn/	Transaction evaluation (If/Then/Else).
server/etcdserver/version/	Server-version + cluster-version negotiation.
server/auth/	RBAC store, simple + JWT tokens, range-permission cache.
server/config/	Server-side Config (consumed by EtcdServer).
server/features/	Server feature-gate registry.
server/lease/	TTL leases, expiration heap, checkpoints.
server/storage/	Storage facade + per-implementation packages.
server/storage/backend/	bbolt wrapper, batched read/write tx, freelist mgmt.
server/storage/datadir/	Layout helpers for <data-dir>.
server/storage/mvcc/	MVCC store, watcher group, hash storage.
server/storage/schema/	Bolt buckets, schema versioning, migrations.
server/storage/wal/	Write-ahead log.
server/proxy/grpcproxy/	gRPC proxy mode (caching).
server/proxy/tcpproxy/	TCP/L4 proxy mode (gateway).
server/verify/	Boot- and shutdown-time invariants (debug builds).
server/mock/	Test doubles for the storage stack.

Cross-cutting choices

• Logging: every constructor accepts a *zap.Logger. The default is structured JSON.
• Metrics: every package owns a metrics.go; metrics are registered to prometheus.DefaultRegisterer.
• Errors: sentinel package-level errors; no panics in normal control flow.
• Concurrency: explicit named mutexes; long-running goroutines are launched with EtcdServer.goAttach so shutdown can wait for them.
• Testing: every non-trivial file ships a corresponding _test.go; the cluster-level tests live in tests/integration/ rather than here.

Active contributors

CODEOWNERS-equivalent lives in OWNERS and OWNERS_ALIASES. Recent committers across server/ (last 90 days) include Benjamin Wang (ahrtr), Marek Siarkowicz (serathius), Chun-Hung Tseng (henrybear327), Jordan Liggitt, Ivan Valdes, Jefftree, joshjms, and Wei Fu.