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A Cloud Guru

Using Prometheus Recording Rules

Prometheus is a great way to collect a variety of metrics for your servers and applications. However, sometimes you need to perform calculations on the raw data Prometheus collects in order to gain actionable information. While queries can help you do this, recording rules provide an additional layer of optimization by allowing you to periodically pre-calculate query results and save them. In this lab, you will have the opportunity to implement some basic recording rules. This will provide you with some hands-on familiarity with the process of creating and managing recording rules.

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Path Info

Level

Intermediate

Duration

45m

Published

Jun 12, 2020

Challenge

Implement a Recording Rule to Pre-Calculate CPU Usage
1. Log in to the Prometheus server.
2. Create a directory to store rules files:
```
sudo mkdir -p /etc/prometheus/rules
```
3. Edit the Prometheus config and add a rules location:
```
sudo vi /etc/prometheus/prometheus.yml
```
```
...

rule_files:
  - "/etc/prometheus/rules/*.yml"

...
```
4. Create a rules file for limedrop-gateway server metrics:
```
sudo vi /etc/prometheus/rules/limedrop-gateway.yml
```
5. Implement a recording rule to pre-calculate CPU usage for the server:
```
groups:
- name: limedrop_gateway
  rules:
  - record: limedrop_gateway:cpu_usage
    expr: sum(rate(node_cpu_seconds_total{instance='limedrop-gateway:9100',mode!='idle'}[5m])) * 100 / 2
```
6. Restart Prometheus to load the new configuration:
```
sudo systemctl restart prometheus
```
7. Access the expression browser (http://<PROMETHEUS_SERVER_PUBLIC_IP>:9090/graph) and run a query to verify you can see the pre-calculated data:
```
limedrop_gateway:cpu_usage[5m]
```

Challenge

Add a Recording Rule to Pre-Calculate Memory Usage

Edit the rules file:

sudo vi /etc/prometheus/rules/limedrop-gateway.yml

Add a recording rule to pre-calculate memory usage for the server:

groups:
- name: limedrop_gateway
  rules:
  - record: limedrop_gateway:cpu_usage
    expr: sum(rate(node_cpu_seconds_total{instance='limedrop-gateway:9100',mode!='idle'}[5m])) * 100 / 2
  - record: limedrop_gateway:memory_usage
    expr: 100 - (node_memory_MemAvailable_bytes{instance='limedrop-gateway:9100'} / node_memory_MemTotal_bytes{instance='limedrop-gateway:9100'}) * 100

Restart Prometheus to load the new configuration:
```
sudo systemctl restart prometheus
```
Access the expression browser (http://<PROMETHEUS_SERVER_PUBLIC_IP>:9090/graph) and run a query to verify you can see the pre-calculated data:
```
limedrop_gateway:memory_usage[5m]
```
You can also check out the rules interface (http://<PROMETHEUS_SERVER_PUBLIC_IP>:9090/rules) to see the status of your rules.

Author

A Cloud Guru

The Cloud Content team comprises subject matter experts hyper focused on services offered by the leading cloud vendors (AWS, GCP, and Azure), as well as cloud-related technologies such as Linux and DevOps. The team is thrilled to share their knowledge to help you build modern tech solutions from the ground up, secure and optimize your environments, and so much more!

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