Chronosphere Collector

About the Collector

The Collector is a standalone app whose main function is to discover and scrape a Prometheus server that's exposed by your app, and then send any discovered data to the Chronosphere service through a connection secured by a revocable API token. If the Collector can't scrape certain jobs or components, you can manually push metrics to it. For more information, refer to Service discovery.

In addition to ingesting metrics, the Collector can:

  • Filter, rename, and drop Prometheus metrics that pass through it by using Prometheus's relabeling rules (opens in a new tab), based on specific label/value pairs.
  • Add global labels to all Prometheus metrics the Collector ingests. For example, you can append all Prometheus metrics passing through a particular Collector with the label service="col1".
  • Receive traces from your services, such as OpenTelemetry spans and other popular open source formats like Jaeger and Zipkin.

Get started with the Collector

The Collector supports IPv4, IPv6, or fully qualified domain names for a single endpoint.

To get started with the Collector:

  1. Review the architecture to determine how you want to install the Collector.
  2. Install the Collector, either to retrieve metric data or receive trace data.
  3. Verify and monitor the Collector to ensure your data is streaming into the Chronosphere app.
  4. Configure service discovery to discover other apps to scrape metrics from.
  5. Enable recommended optimizations and modify default settings.
  6. Optional: Ingest additional metrics such as DogStatsD, Graphite, Prometheus, or Pushgateway.

If you're using Kubernetes, you can also modify the scrape configuration to override scrape defaults, change the annotation prefix, and define the jobs configuration.

Architecture

You can install the Collector with Kubernetes as a DaemonSet, Deployment, or as a sidecar. Each of these models have pros and cons, with different architectures.

DaemonSet

Installing the Collector as a Kubernetes DaemonSet is a pull-based model, where the Collector scrapes endpoints using either annotations or ServiceMonitors. With this method, you deploy a Collector on every node in your cluster. This method is the recommended way to install the Collector to receive metrics.

Collector DaemonSet architecture

Pros

Because the Collector resides on the same Kubernetes node as your app, latency is low. As your cluster grows, deploy a Collector on each new node to scale your cluster horizontally. Installing one Collector per node also means that you're less likely to overload any single Collector.

This method allows for phased rollouts of new Collector versions and configuration changes to help avoid losing scrape coverage. Also, if you lose a node, you're only losing metrics for that node and not your entire cluster.

Cons

Some environments, such as AWS Fargate, restrict you from deploying an app as a DaemonSet. Kubernetes applies resource requirements globally across your cluster, which means that DaemonSets can evict other applications from the node depending on prioritization. Also, DaemonSets don't deal well with noisy scrape endpoints, such as kube-state-metrics.

Deployment

Installing the Collector as a Kubernetes Deployment works best for push-based models, where your app pushes data to a Kubernetes Service, which the Collector receives data from. This method is the recommended way to install the Collector to receive distributed trace data.

To install the Collector in a Deployment where it pulls metrics data from scrape targets, Chronosphere recommends using Prometheus Service Discovery. If you don't need Pod metadata, you can install the Collector in a Deployment using ServiceMonitors.

Collector Deployment architecture

Pros

Deployments work well for monitoring high cardinality endpoints. You can choose to either configure multiple Collectors in your cluster or deploy a singular Collector. You can also select the number of Collectors to run in your cluster. As your cluster grows, add more Pods to scale your Deployment horizontally.

Cons

If you deploy a singular Collector that's undersized for your workload, the Collector might experience delays in scrape latency or encounter out of memory situations. A Deployment can also be problematic when using staleness markers, and you can't customize the push configuration of the Collector per app.

Sidecar

A sidecar is a dedicated resource for your app that's ideal for handling high volume data, such an app that generates copious time series data. To run the Collector as a sidecar, you can install an individual Collector in each Pod of your cluster. Because the Collector Container and app Container run on the same Pod, you can optimize resources for the Pod.

Collector sidecar architecture

Pros

If a Collector goes offline, you lose only the metrics for a single Pod. You have more control over resource usage for high cardinality apps and can customize the Collector per app.

Cons

Each Pod requires a sidecar Container, which requires additional Kubernetes resources for your cluster. Sidecars require you to maintain the app manifest to include the Collector as a sidecar, which increases overhead. Because the Collector exists on the same Pod as your app Container, the Collector can impact the entire Pod if it experiences problems.