Production-Ready Template

Production-Ready Redis Monitoring with Prometheus Alert Templates

Redis is a critical component in modern infrastructure, serving as a high-performance in-memory data store and cache. Ensuring its health and availability is essential for application performance and reliability. This blog explores how to monitor Redis effectively using Prometheus and a set of pre-built community alert rules from the DrDroidLab/prometheus-alert-templates GitHub repository. These alerts cover critical failure modes, performance degradation, and resource exhaustion, enabling site reliability engineers (SREs), DevOps teams, and infrastructure managers to detect and resolve issues proactively.

Core Alert Rule

RedisDown
Critical Performance Bottleneck
redis_up == 0
Why this matters
Fires when the Redis exporter reports that the Redis instance is down or unreachable. This could indicate a crash, connectivity issue, or configuration error.
Tuning tips
Increase the evaluation interval or add for-duration (e.g., for: 2m) to avoid noise during brief restarts or exporter hiccups.
RedisOutOfMemory
Operations blocking event loop
redis_memory_used_bytes / redis_memory_max_bytes > 0.9
Why this matters
Triggers when Redis is using more than 90% of its maximum memory limit, indicating possible eviction pressure, memory leaks, or misconfigured limits.
Tuning tips
Adjust the threshold if your workload tolerates higher memory usage or tune `maxmemory-policy` in Redis accordingly.
RedisTooManyConnections
Memory efficiency warning
redis_connected_clients > 1000
Why this matters
Alerts when the number of active client connections exceeds 1000, which may indicate client connection leaks or denial-of-service (DoS) attempts.
Tuning tips
Tune the threshold based on expected connection volume, and ensure connection pooling or rate-limiting on clients is in place.
RedisReplBacklogFull
Service availability check
redis_replication_backlog_histlen / redis_replication_backlog_size_bytes > 0.9
Why this matters
Indicates that the Redis replication backlog is close to full, which can compromise the ability of replicas to re-sync without a full resync.
Tuning tips
Increase `repl-backlog-size` in Redis or reduce replica reconnection frequency.
RedisRoleChange
Service availability check
changes(redis_instance_info{role='master'}[5m]) > 0
Why this matters
Fires when a Redis instance switches roles unexpectedly (e.g., master to replica), which may indicate failover events or misconfigurations.
Tuning tips
Use this in HA deployments only. Add `for: 5m` to reduce flapping alerts during legitimate failovers.
Service availability check
Why this matters
Clone the alert templates repository from GitHub: git clone https://github.com/DrDroidLab/prometheus-alert-templates.git
Tuning tips
Copy the redis alert file (redis.rules) into your Prometheus configuration folder.
Service availability check
Why this matters
Tuning tips
Service availability check
Why this matters
Tuning tips

Quick Setup

1
Include the alert rule file in your Prometheus configuration under 'rule_files': e.g., rule_files: ["redis.rules"]
2
Reload Prometheus to apply the new alert rules: `kill -HUP $(pidof prometheus)` or restart the service
3
Ensure Alertmanager is configured to receive alerts and route accordingly.
4
How do I ensure these alerts work with custom Redis exporters?
5
These alerts assume standard Redis exporter metrics. If you're using a fork or customized exporter, validate metric names.

Frequently Asked Questions

What namespace or job label does this template assume?
Can these alerts be used in Kubernetes?
What Prometheus version is required?

Ready to Get Started?

Start monitoring your Redis instances more reliably today by integrating the Redis alert rules from the DrDroidLab prometheus-alert-templates GitHub repo. These pre-defined alerts provide a production-ready foundation for observability teams focused on Redis health and availability.

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