Prometheus is an open-source systems monitoring and alerting toolkit originally built at SoundCloud. It is designed for reliability and scalability, making it a popular choice for monitoring applications and infrastructure. Prometheus collects metrics from configured targets at given intervals, evaluates rule expressions, displays the results, and can trigger alerts if certain conditions are observed.
One common issue users encounter is when Prometheus is not scraping new metrics. This means that even though new metrics are expected to be collected, they do not appear in Prometheus's database or queries. This can be frustrating as it prevents accurate monitoring and alerting based on the latest data.
The primary reasons for Prometheus not scraping new metrics include:
If Prometheus fails to scrape new metrics, it can lead to outdated data being used for monitoring and alerting, potentially causing missed alerts or incorrect insights into system performance.
First, ensure that the target application is exposing the new metrics. You can do this by accessing the metrics endpoint directly in your browser or using a tool like curl:
curl http://your-target:port/metrics
Check if the new metrics are listed in the output.
Next, verify that the Prometheus configuration file (prometheus.yml) is correctly set up to scrape the target. Ensure that the job name and target endpoint are correctly specified:
scrape_configs:
- job_name: 'your-job-name'
static_configs:
- targets: ['your-target:port']
After making changes, reload the Prometheus configuration by sending a SIGHUP signal or using the web interface.
Ensure that the scrape interval is appropriate for your needs. If the interval is too long, it might seem like metrics are not being updated. Adjust the scrape_interval as needed:
scrape_interval: 15s
Review the Prometheus logs for any errors related to scraping. This can provide insights into what might be going wrong. Logs can be accessed via the command line or through your logging system:
docker logs prometheus-container
By following these steps, you should be able to diagnose and resolve issues related to Prometheus not scraping new metrics. For more detailed information, refer to the Prometheus documentation and the configuration guide.
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