redis-observability

# Redis Observability What to watch, what to run, and what to alert on. Covers the metrics every Redis deployment should monitor and the built-in commands for ad-hoc diagnosis. ## When to apply - Setting up monitoring or alerts for a Redis instance. - Diagnosing a Redis performance regression (high latency, memory pressure, connection storms). - Profiling a slow `FT.SEARCH` or pipeline. - Wiring Redis metrics into Prometheus, Datadog, CloudWatch, or similar. ## 1. Monitor these metrics These come from `INFO` and should be exported to your monitoring system. | Metric | What it tells you | Alert when | |---|---|---| | `used_memory` | Current memory usage | > 80% of `maxmemory` | | `connected_clients` | Open connections | Sudden spikes or drops | | `blocked_clients` | Clients waiting on blocking ops | > 0 sustained | | `instantaneous_ops_per_sec` | Current throughput | Significant drops | | `keyspace_hits` / `keyspace_misses` | Cache hit ratio | Hit ratio < 80% | | `rejected_connections` | Hit `maxclients` cap | > 0 | | `rdb_last_save_time` | Last persistence snapshot | Too old vs. RPO | ```python info = redis.info() hit_ratio = info["keyspace_hits"] / max(1, info["keyspace_hits"] + info["keyspace_misses"]) print(f"Memory: {info['used_memory_human']}") print(f"Clients: {info['connected_clients']}") print(f"Ops/sec: {info['instantaneous_ops_per_sec']}") print(f"Hit ratio: {hit_ratio:.1%}") ``` See [references/metrics.md](references/metrics.md). ## 2. Built-in commands for debugging Reach for these when something looks off. | Topic | Command | |---|---| | Slow commands | `SLOWLOG GET 10` / `SLOWLOG LEN` / `SLOWLOG RESET` | | Server snapshot | `INFO all` (or `INFO memory` / `INFO stats` / `INFO clients` / `INFO replication`) | | Memory diagnostics | `MEMORY DOCTOR` / `MEMORY STATS` / `MEMORY USAGE <key>` | | Connections | `CLIENT LIST` / `CLIENT INFO` | | RQE / Search | `FT.INFO <idx>` / `FT.PROFILE <idx> SEARCH QUERY "..."` | The two most useful for incident triage: - **`SLOWLOG GET`** to find queries that exceeded the `slowlog-log-slower-than` threshold (10ms by default). The output shows the exact command and duration in microseconds. - **`MEMORY DOCTOR`** for memory pressure — it returns a one-paragraph summary of what's unusual about memory usage right now. ```python for entry in redis.slowlog_get(10): print(f"{entry['duration']}μs {entry['command']}") ``` See [references/commands.md](references/commands.md). ## 3. Redis Insight For interactive use (running queries, browsing keys, profiling indexes), [Redis Insight](https://redis.io/insight/) is the official GUI. It surfaces the same `SLOWLOG` / `INFO` / `FT.PROFILE` data visually and includes Redis Copilot for natural-language queries. Useful during development and incident response; not a replacement for exporting metrics to your monitoring system. ## References - [Redis: Latency monitoring](https://redis.io/docs/latest/operate/oss_and_stack/management/optimization/latency/) - [Redis Insight](https://redis.io/insight/)