docs: raft cluster status, plans closed, CHANGELOG/README/monitoring
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- Add raft-cluster-status overview (C3a/C3b/post-C3b shipped on main)
- Mark C3a/C3b design+plans done; refresh operator docs en/bg
- CHANGELOG 1.2.0 Raft section; README cluster example and status line
- monitoring.md health/metrics match real HTTP port+440 and raft series
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2026-07-30 21:41:15 +03:00
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commit 16ec8b5dc4
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@@ -5,9 +5,11 @@ BaraDB supports distributed deployment with Raft consensus, sharding, and replic
> ⚠️ **Multi-Database Limitation**
> The distributed modules (Raft, sharding, and replication) are currently wired to the **`default`** database only. If you use multiple databases (`CREATE DATABASE`, `USE DATABASE`), distributed features do not yet span across them. Each database would need its own cluster setup.
> **Status (2026-07-30):** Raft C3a (network election), C3b (SQL writes), DDL replication, leader forwarding, log compaction, and metrics are **shipped on `main`**. Design/history: `docs/superpowers/specs/2026-07-30-raft-cluster-status.md`.
## Raft Consensus
Leader election and log replication over TCP. Enable with:
Leader election and log replication over TCP; SQL DML/DDL on the default DB go through the raft log. Enable with:
| Env | Meaning |
|-----|---------|
@@ -25,6 +27,26 @@ When Raft is enabled, SQL DML (`INSERT`/`UPDATE`/`DELETE`/`MERGE` and transactio
**Metrics:** with raft enabled, `GET /metrics` (HTTP port = `BARADB_PORT + 440`) includes Prometheus lines such as `baradb_raft_is_leader`, `baradb_raft_term`, `baradb_raft_log_entries`, `baradb_raft_apply_lag`, `baradb_raft_commit_wait_ms_total`, `baradb_raft_elections_total`, `baradb_raft_forwards_total`, and `baradb_raft_compactions_total`. `GET /health` embeds a `raft` object (`role`, `term`, `leader_id`, `commit_index`, `apply_lag`, …).
### Minimal 3-node example
```bash
# Shared peers (raft ports) and client peers (SQL ports)
export BARADB_RAFT_ENABLED=true
export BARADB_RAFT_PEERS=n1@127.0.0.1:46101,n2@127.0.0.1:46102,n3@127.0.0.1:46103
export BARADB_RAFT_CLIENT_PEERS=n1@127.0.0.1:46010,n2@127.0.0.1:46020,n3@127.0.0.1:46030
# Terminal 1
BARADB_PORT=46010 BARADB_RAFT_PORT=46101 BARADB_RAFT_NODE_ID=n1 \
BARADB_DATA_DIR=./data/n1 ./build/baradadb
# Terminal 2 / 3 — n2@46020/46102, n3@46030/46103 similarly
# After a leader appears (check logs for "became leader"):
# curl http://127.0.0.1:46450/health # n1 HTTP = 46010+440
```
### In-process API (tests / embedding)
```nim
import barabadb/core/raft
@@ -39,6 +61,13 @@ n1.becomeLeader()
let entry = n1.appendLog("SET key1 value1")
```
### E2E tests
| Test | What it proves |
|------|----------------|
| `tests/raft_e2e_test.nim` | 3 real processes; election + kill-leader failover |
| `tests/raft_writes_e2e_test.nim` | DDL/DML via raft, follower forward, index SELECT, failover writes |
## Sharding
Distribute data across nodes:
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@@ -4,21 +4,39 @@
### HTTP Health Endpoint
HTTP listens on **TCP port + 440** (e.g. `BARADB_PORT=9472` → health on `9912`).
```bash
curl http://localhost:9470/health
curl http://localhost:9912/health
```
Response:
Response (raft disabled):
```json
{
"status": "healthy",
"version": "0.1.0",
"uptime_seconds": 86400,
"checks": {
"storage": "ok",
"memory": "ok",
"connections": "ok"
"status": "ok",
"version": "1.1.6",
"raft": { "enabled": false }
}
```
With `BARADB_RAFT_ENABLED=true`, a `raft` object is included:
```json
{
"status": "ok",
"version": "1.1.6",
"raft": {
"enabled": true,
"node_id": "n1",
"role": "leader",
"term": 2,
"leader_id": "n1",
"commit_index": 42,
"last_applied": 42,
"apply_lag": 0,
"log_entries": 12,
"snapshot_index": 30
}
}
```
@@ -35,10 +53,38 @@ Returns `200 OK` when the server is ready to accept traffic, `503` during startu
### Prometheus-Compatible Metrics
Same HTTP base port as health (`BARADB_PORT + 440`). When auth is enabled, send a Bearer token.
```bash
curl http://localhost:9470/metrics
curl http://localhost:9912/metrics
```
Always present:
| Metric | Meaning |
|--------|---------|
| `baradb_queries_total` | HTTP queries handled |
| `baradb_query_errors_total` | Failed HTTP queries |
| `baradb_inserts_total` / `baradb_selects_total` | Statement class counts |
| `baradb_connections_active` | Active connections |
With raft enabled, additional series (labels include `node="…"`):
| Metric | Meaning |
|--------|---------|
| `baradb_raft_is_leader` | 1 if this process is leader |
| `baradb_raft_term` | Current term |
| `baradb_raft_log_entries` | In-memory log length |
| `baradb_raft_commit_index` / `baradb_raft_last_applied` | Raft indices |
| `baradb_raft_apply_lag` | commit applied |
| `baradb_raft_snapshot_index` | Compacted log base |
| `baradb_raft_elections_total` | Times this node became leader |
| `baradb_raft_commit_wait_ms_total` / `_avg` | Wait-for-commit latency |
| `baradb_raft_forwards_total` | Follower→leader SQL forwards |
| `baradb_raft_compactions_total` | Log prefix compactions |
See also [distributed.md](distributed.md) for cluster env vars and ops notes.
Example output:
```