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76 lines
3.1 KiB
Markdown
76 lines
3.1 KiB
Markdown
Kubernetes Custom Metrics Adapter for Prometheus
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================================================
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[](https://travis-ci.org/DirectXMan12/k8s-prometheus-adapter)
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This repository contains an implementation of the Kubernetes custom
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metrics API
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([custom-metrics.metrics.k8s.io/v1alpha1](https://github.com/kubernetes/metrics/tree/master/pkg/apis/custom_metrics)),
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suitable for use with the autoscaling/v2 Horizontal Pod Autoscaler in
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Kubernetes 1.6+.
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Configuration
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-------------
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The adapter takes the standard Kubernetes generic API server arguments
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(including those for authentication and authorization). By default, it
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will attempt to using [Kubernetes in-cluster
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config](https://kubernetes.io/docs/tasks/access-application-cluster/access-cluster/#accessing-the-api-from-a-pod)
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to connect to the cluster.
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It takes the following addition arguments specific to configuring how the
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adapter talks to Prometheus and the main Kubernetes cluster:
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- `--lister-kubeconfig=<path-to-kubeconfig>`: This configures
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how the adapter talks to a Kubernetes API server in order to list
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objects when operating with label selectors. By default, it will use
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in-cluster config.
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- `--metrics-relist-interval=<duration>`: This is the interval at which to
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update the cache of available metrics from Prometheus.
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- `--rate-interval=<duration>`: This is the duration used when requesting
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rate metrics from Prometheus. It *must* be larger than your Prometheus
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collection interval.
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- `--prometheus-url=<url>`: This is the URL used to connect to Prometheus.
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It will eventually contain query parameters to configure the connection.
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Presentation
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------------
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The adapter gathers the names of available metrics from Prometheus
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a regular interval (see [Configuration](#configuration) above), and then
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only exposes metrics that follow specific forms.
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In general:
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- Metrics must have the `namespace` label to be considered.
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- For each label on a metric, if that label name corresponds to
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a Kubernetes resource (like `pod` or `service`), the metric will be
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associated with that resource.
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- Metrics ending in `_total` are assumed to be cumulative, and will be
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exposed without the suffix as a rate metric.
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Detailed information can be found under [docs/format.md](docs/format.md).
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Example
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-------
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A brief walkthrough exists in [docs/walkthrough.md](docs/walkthrough.md).
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Additionally, [@luxas](https://github.com/luxas) has an excellent example
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deployment of Prometheus, this adapter, and a demo pod which serves
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a metric `http_requests_total`, which becomes the custom metrics API
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metric `pods/http_requests`. It also autoscales on that metric using the
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`autoscaling/v2alpha1` HorizontalPodAutoscaler.
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It can be found at https://github.com/luxas/kubeadm-workshop. Pay special
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attention to:
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- [Deploying the Prometheus
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Operator](https://github.com/luxas/kubeadm-workshop#deploying-the-prometheus-operator-for-monitoring-services-in-the-cluster)
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- [Setting up the custom metrics adapter and sample
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app](https://github.com/luxas/kubeadm-workshop#deploying-a-custom-metrics-api-server-and-a-sample-app)
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