VictoriaMetrics: Enhance Monitoring With Scrape Classes

Hey guys! Let's dive into a cool feature request for VictoriaMetrics. We're talking about supporting Scrape Classes, a concept from the Prometheus Operator that's super helpful, especially when you're using Istio. This addition would really level up how we monitor our systems, making things more flexible and secure. So, what's the deal with Scrape Classes, and why should VictoriaMetrics jump on board? Let's break it down.

The Need for Scrape Classes: Why It Matters

So, why do we even need Scrape Classes? Well, it all boils down to how we handle secure communication, particularly with Istio. When you're using Istio, you often need to configure TLS settings for secure connections. The Prometheus Operator provides CRDs (Custom Resource Definitions) like ServiceMonitor, PodMonitor, and Probe to define how Prometheus scrapes metrics from your applications. The challenge arises with how these CRDs handle TLS configurations, especially when Istio is in the mix. The current setup uses v1.TLSConfig for ServiceMonitors, which allows specifying caFile, certFile, and keyFile. However, newer CRDs like Probe and PodMonitor use v1.SafeTLSConfig, which, for security reasons, intentionally omits these file paths. This incompatibility creates a problem because Istio often requires these file paths for secure, mTLS-enabled communication.

This is where Scrape Classes come in. Scrape Classes provide a way to define common configurations that can be applied to various scraping targets. By supporting Scrape Classes, VictoriaMetrics could offer a standardized way to manage these TLS configurations, ensuring that all CRDs can work seamlessly with Istio's mTLS requirements. This would not only simplify configuration but also enhance security by allowing consistent management of TLS settings across all your monitoring targets. It's about making sure that all your monitoring components can communicate securely and efficiently, especially when they're part of a complex system like an Istio-enabled environment. Getting VictoriaMetrics on board with this is a win-win: better compatibility, easier setup, and improved security for everyone. It's a key piece of the puzzle for smooth operations.

Background: The Journey of Scrape Classes

The story of Scrape Classes is pretty interesting. It shows how the community recognized a problem and worked together to find a solution. It goes back to 2021 when the Prometheus Operator community started discussing the security implications of SafeTLSConfig. The main concern was that including the xFile constructs (like caFile, certFile, and keyFile) could potentially expose sensitive information. Fast forward to June 2021, and the incompatibility issue between SafeTLSConfig and Istio became clear. This led to the idea of using Scrape Classes to bridge the gap.

Fast forward to May 2023, a proposal was made to integrate Scrape Classes into the Prometheus Operator. Then, by November 2023, Scrape Classes were officially added to the Prometheus Operator, showing the community's commitment to finding a robust solution. This collaborative effort highlights how important it is to adapt and evolve to meet the challenges of modern cloud-native environments. By adopting Scrape Classes, tools like VictoriaMetrics can ensure they stay compatible with best practices and provide users with the most secure and efficient monitoring solutions.

Current Workarounds: Making Things Work

Let's talk about the situation right now. Suppose you want to use blackbox_exporter with Probe CRDs, but your vmagent is running outside Istio, while blackbox_exporter is inside the mesh. You'll run into the issue we've been discussing, and the Probe CRD won't work out of the box. So, what do you do?

Well, the current workaround involves a bit of Istio magic. You can create a PeerAuthentication policy that allows non-mesh/mTLS traffic to reach the blackbox_exporter. It's essentially loosening the security just a bit to let the traffic through. Also, you might tweak Istio further by adding the annotation networking.istio.io/exportTo: “.” to the Service, which stops it from being exposed outside the namespace. And, you can also add an AuthorizationPolicy to control access more finely. It's not the perfect solution, and it might seem a bit of a hack, but it gets the job done. It's all about making things work, given the current limitations. These workarounds demonstrate the need for a more integrated solution like Scrape Classes, which would simplify these complex setups and make everything more streamlined and secure. These steps are a practical way to deal with the issues until a more sustainable solution, like VictoriaMetrics support for Scrape Classes, becomes available. It's about making the best of what we've got!

The Ideal Solution: Supporting Scrape Classes in VictoriaMetrics

The best solution here is straightforward: VictoriaMetrics should support Scrape Classes. Imagine a scenario where VictoriaMetrics can understand and handle these configurations. Specifically, it should support the common Prometheus Operator CRDs like ServiceMonitor, PodMonitor, and Probe. These CRDs would then be