Different Prometheus Scrape Url for Every Target

To configure Prometheus to use different scrape URLs for each target, you can leverage the relabel_configs section in your prometheus.yml file. This allows you to define specific scrape configurations per target. Here’s how to set it up:

Example Configuration

Below is an example of a prometheus.yml configuration that demonstrates how to use different scrape URLs for each target:

global:
  scrape_interval: 15s

scrape_configs:
  - job_name: 'my_application'
    static_configs:
      - targets:
          - 'localhost:9090'  # Default target
          - 'example.com:8080'  # Another target with default URL
          - 'localhost:3000'  # A different target with a different URL
    relabel_configs:
      # First target
      - source_labels: [__address__]
        target_label: __address__
        replacement: 'localhost:9090'  # Scrape URL for localhost
        regex: 'localhost:.*'
      # Second target
      - source_labels: [__address__]
        target_label: __address__
        replacement: 'example.com:8080'  # Scrape URL for example.com
        regex: 'example.com:.*'
      # Third target
      - source_labels: [__address__]
        target_label: __address__
        replacement: 'localhost:3000'  # Scrape URL for localhost:3000
        regex: 'localhost:.*'

Explanation of the Configuration

1. Job Definition: The job_name defines the logical grouping of the targets you are scraping.
2. Static Configurations: The targets section lists the targets. You can list multiple targets here, and they can have different URLs.
3. Relabeling:
   • The relabel_configs section allows you to modify how targets are scraped.
   • source_labels: This specifies which label to check (in this case, __address__).
   • target_label: Here, you redefine the __address__ label to the specific scrape URL you want for each target.
   • replacement: This defines what the __address__ label will be set to for scraping. You specify the actual URL to scrape.
   • regex: This is used to match specific targets, allowing you to differentiate between them.

Tips for Configuring Different URLs

• Dynamic Targets: If your targets are dynamic (e.g., in a cloud environment or using service discovery), you might want to use service discovery mechanisms instead of static configurations.
• Using Service Discovery: Prometheus supports various service discovery mechanisms (like Kubernetes, Consul, etc.) which can be configured to automatically scrape metrics from dynamically changing endpoints.

Conclusion

By utilizing the relabel_configs section in your Prometheus configuration, you can effectively set different scrape URLs for each target. This is particularly useful when working with multiple services or instances that expose metrics at different endpoints.

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