Redis

This document describes how to configure your Google Kubernetes Engine deployment so that you can use Google Cloud Managed Service for Prometheus to collect metrics from Redis. This document shows you how to do the following:

Set up the exporter for Redis to report metrics.
Configure a PodMonitoring resource for Managed Service for Prometheus to collect the exported metrics.
Access a dashboard in Cloud Monitoring to view the metrics.
Configure alerting rules to monitor the metrics.

These instructions apply only if you are using managed collection with Managed Service for Prometheus. If you are using self-deployed collection, then see the source repository for the Redis exporter for installation information.

These instructions are provided as an example and are expected to work in most Kubernetes environments. If you are having trouble installing an application or exporter due to restrictive security or organizational policies, we recommend you consult open-source documentation for support.

For information about Redis, see Redis.

Prerequisites

To collect metrics from Redis by using Managed Service for Prometheus and managed collection, your deployment must meet the following requirements:

Your cluster must be running Google Kubernetes Engine version 1.21.4-gke.300 or later.
You must be running Managed Service for Prometheus with managed collection enabled. For more information, see Get started with managed collection.
To use dashboards available in Cloud Monitoring for the Redis integration, you must use redis_exporter version v1.43.1 or later.
For more information about available dashboards, see View dashboards.

Install the Redis exporter

We recommend that you install the Redis exporter, redis_exporter, as a sidecar to your Redis workload. For information about using sidecars, see Extended applications on Kubernetes with multi-container pods.

To install redis_exporter as a sidecar to Redis, modify your Redis configuration as shown in the following example:

# Copyright 2022 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     https:#www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: redis
  labels:
    app.kubernetes.io/name: redis
spec:
  selector:
    matchLabels:
+     app.kubernetes.io/name: redis
  template:
    metadata:
      labels:
+       app.kubernetes.io/name: redis
    spec:
      containers:
      - name: redis
        image: "redis:6.2"
        ... 
+     - name: redis-exporter
+       image: oliver006/redis_exporter:v1.43.1
+       args: [--include-system-metrics]
+       resources:
+         requests:
+           cpu: 100m
+           memory: 100Mi
+       ports:
+       - containerPort: 9121
    ...

You must add any lines preceded by the + symbol to your configuration.

These instructions assume you already have a working Redis installation and want to modify it to include an exporter. If you need to also set up Redis, you can configure and apply the Bitnami Helm chart. Pass in the following configuration values:

metrics.enabled = true
metrics.podLabels = {app.kubernetes.io/name: redis}

To apply configuration changes from a local file, run the following command:

kubectl apply -n NAMESPACE_NAME -f FILE_NAME

You can also use Terraform to manage your configurations.

Define a PodMonitoring resource

For target discovery, the Managed Service for Prometheus Operator requires a PodMonitoring resource that corresponds to the Redis exporter in the same namespace.

You can use the following PodMonitoring configuration:

# Copyright 2022 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

apiVersion: monitoring.googleapis.com/v1
kind: PodMonitoring
metadata:
  name: redis
  labels:
    app.kubernetes.io/name: redis
    app.kubernetes.io/part-of: google-cloud-managed-prometheus
spec:
  selector:
    matchLabels:
      app.kubernetes.io/name: redis
  endpoints:
  - port: 9121
    interval: 30s

Ensure that the label selectors and the port match the selectors and port used in Install the Redis exporter.

To apply configuration changes from a local file, run the following command:

kubectl apply -n NAMESPACE_NAME -f FILE_NAME

You can also use Terraform to manage your configurations.

Define rules and alerts

You can use the following Rules configuration to define alerts on your Redis metrics:

# Copyright 2022 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

apiVersion: monitoring.googleapis.com/v1
kind: Rules
metadata:
  name: redis-rules
  labels:
    app.kubernetes.io/component: rules
    app.kubernetes.io/name: redis-rules
    app.kubernetes.io/part-of: google-cloud-managed-prometheus
spec:
  groups:
  - name: redis
    interval: 30s
    rules:
    - alert: RedisDown
      annotations:
        description: |-
          Redis instance is down 
            VALUE = {{ $value }}
            LABELS: {{ $labels }}
        summary: Redis down (instance {{ $labels.instance }})
      expr: redis_up{job="redis"} == 0
      for: 5m
      labels:
        severity: critical
    - alert: RedisOutOfMemory
      annotations:
        description: |-
          Redis is running out of memory (> 90%)
            VALUE = {{ $value }}
            LABELS: {{ $labels }}
        summary: Redis out of memory (instance {{ $labels.instance }})
      expr: redis_memory_used_bytes{job="redis"} / redis_total_system_memory_bytes{job="redis"}
        * 100 > 90
      for: 5m
      labels:
        severity: warning
    - alert: RedisTooManyConnections
      annotations:
        description: |-
          Redis instance has too many connections
            VALUE = {{ $value }}
            LABELS: {{ $labels }}
        summary: Redis too many connections (instance {{ $labels.instance }})
      expr: redis_connected_clients{job="redis"} > 100
      for: 5m
      labels:
        severity: warning
    - alert: RedisClusterSlotFail
      annotations:
        description: |-
          Redis cluster has slots fail
            VALUE = {{ $value }}
            LABELS: {{ $labels }}
        summary: Number of hash slots mapping to a node in FAIL state (instance {{ $labels.instance }})
      expr: redis_cluster_slots_fail{job="redis"} > 0
      for: 5m
      labels:
        severity: warning
    - alert: RedisClusterSlotPfail
      annotations:
        description: |-
          Redis cluster has slots pfail
            VALUE = {{ $value }}
            LABELS: {{ $labels }}
        summary: Number of hash slots mapping to a node in PFAIL state (instance {{ $labels.instance }})
      expr: redis_cluster_slots_pfail{job="redis"} > 0
      for: 5m
      labels:
        severity: warning
    - alert: RedisClusterStateNotOk
      annotations:
        description: |-
          Redis cluster is not ok 
            VALUE = {{ $value }}
            LABELS: {{ $labels }}
        summary: Redis cluster state is not ok (instance {{ $labels.instance }})
      expr: redis_cluster_state{job="redis"} == 0
      for: 5m
      labels:
        severity: critical
    - expr: redis_memory_used_rss_bytes{job="redis"} / redis_memory_used_bytes{job="redis"}
      record: redis_memory_fragmentation_ratio

To apply configuration changes from a local file, run the following command:

kubectl apply -n NAMESPACE_NAME -f FILE_NAME

You can also use Terraform to manage your configurations.

For more information about applying rules to your cluster, see Managed rule evaluation and alerting.

This Rules configuration was adapted from the rules and alerts contributed to the redis_exporter repository.

Verify the configuration

You can use Metrics Explorer to verify that you correctly configured the Redis exporter. It might take one or two minutes for Cloud Monitoring to ingest your metrics.

To verify the metrics are ingested, do the following:

In the navigation panel of the Google Cloud console, select Monitoring, and then select Metrics explorer:
Go to Metrics explorer
In the toolbar of the query-builder pane, select the button whose name is either MQL or PromQL.
Verify that PromQL is selected in the Language toggle. The language toggle is in the same toolbar that lets you format your query.

Enter and run the following query:

up{job="redis", cluster="CLUSTER_NAME", namespace="NAMESPACE_NAME"}

View dashboards

The Cloud Monitoring integration includes the Redis Prometheus Overview dashboard. Dashboards are automatically installed when you configure the integration. You can also view static previews of dashboards without installing the integration.

To view an installed dashboard, do the following:

In the navigation panel of the Google Cloud console, select Monitoring, and then select Dashboards:
Go to Dashboards
Select the Dashboard List tab.
Choose the Integrations category.
Click the name of the dashboard, for example, Redis Prometheus Overview.

To view a static preview of the dashboard, do the following:

In the navigation panel of the Google Cloud console, select Monitoring, and then select Integrations:
Go to Integrations
Click the Kubernetes Engine deployment-platform filter.
Locate the Redis integration and click View Details.
Select the Dashboards tab.

Troubleshooting

For information about troubleshooting metric ingestion problems, see Problems with collection from exporters in Troubleshooting ingestion-side problems.