Previous change logs can be found at [CHANGELOG-3.4](https://github.com/coreos/etcd/blob/master/CHANGELOG-3.4.md).


## v3.5.0 (TBD 2018-12)

See [code changes](https://github.com/coreos/etcd/compare/v3.4.0...v3.5.0) and [v3.5 upgrade guide](https://github.com/coreos/etcd/blob/master/Documentation/upgrades/upgrade_3_5.md) for any breaking changes. **Again, before running upgrades from any previous release, please make sure to read change logs below and [v3.5 upgrade guide](https://github.com/coreos/etcd/blob/master/Documentation/upgrades/upgrade_3_5.md).**

### Breaking Changes

- [gRPC gateway](https://github.com/grpc-ecosystem/grpc-gateway) only supports [`/v3`](TODO) endpoint.
  - Deprecated [`/v3beta`](https://github.com/coreos/etcd/pull/9298).
  - `curl -L http://localhost:2379/v3beta/kv/put -X POST -d '{"key": "Zm9v", "value": "YmFy"}'` does work in v3.5. Use `curl -L http://localhost:2379/v3/kv/put -X POST -d '{"key": "Zm9v", "value": "YmFy"}'` instead.
- **`etcd --log-output` flag has been deprecated.** Use **`etcd --log-outputs`** instead.
- **`etcd --logger=zap --log-outputs=stderr`** is now the default.
- **`etcd --logger=capnslog` flag has been deprecated.**
- **`etcd --logger=zap --log-outputs=default` flag value is not supported.**.
  - Instead, use `etcd --logger=zap --log-outputs=stderr`.
  - Or, use `etcd --logger=zap --log-outputs=systemd/journal` to send logs to the local systemd journal.
  - Previously, if etcd parent process ID (PPID) is 1 (e.g. run with systemd), `etcd --logger=capnslog --log-outputs=default` redirects server logs to local systemd journal. And if write to journald fails, it writes to `os.Stderr` as a fallback.
  - However, even with PPID 1, it can fail to dial systemd journal (e.g. run embedded etcd with Docker container). Then, [every single log write will fail](https://github.com/coreos/etcd/pull/9729) and fall back to `os.Stderr`, which is inefficient.
  - To avoid this problem, systemd journal logging must be configured manually.
- **`etcd --log-outputs=stderr`** is now the default.
- **`etcd --log-package-levels` flag for `capnslog` has been deprecated.** Now, **`etcd --logger=zap --log-outputs=stderr`** is the default.
- **`[CLIENT-URL]/config/local/log` endpoint has been deprecated, as is `etcd --log-package-levels` flag.**
  - `curl http://127.0.0.1:2379/config/local/log -XPUT -d '{"Level":"DEBUG"}'` won't work.
  - Please use `etcd --logger=zap --log-outputs=stderr` instead.
- Deprecated `etcd_debugging_mvcc_db_total_size_in_bytes` Prometheus metric. Instead, use `etcd_mvcc_db_total_size_in_bytes`.

### Metrics, Monitoring

See [List of metrics](https://etcd.readthedocs.io/en/latest/operate.html#latest) for all metrics per release.

Note that any `etcd_debugging_*` metrics are experimental and subject to change.

- Deprecated `etcd_debugging_mvcc_db_total_size_in_bytes` Prometheus metric. Instead, use `etcd_mvcc_db_total_size_in_bytes`.

### gRPC gateway

- [gRPC gateway](https://github.com/grpc-ecosystem/grpc-gateway) only supports [`/v3`](TODO) endpoint.
  - Deprecated [`/v3beta`](https://github.com/coreos/etcd/pull/9298).
  - `curl -L http://localhost:2379/v3beta/kv/put -X POST -d '{"key": "Zm9v", "value": "YmFy"}'` does work in v3.5. Use `curl -L http://localhost:2379/v3/kv/put -X POST -d '{"key": "Zm9v", "value": "YmFy"}'` instead.