55 lines
3.5 KiB
Markdown
55 lines
3.5 KiB
Markdown
# Load Watcher [](https://pkg.go.dev/github.com/paypal/load-watcher)  [](https://github-tools.github.io/github-release-notes/)
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The load watcher is responsible for the cluster-wide aggregation of resource usage metrics like CPU, memory, network, and IO stats over time windows from a metrics provider like SignalFx, Prometheus, Kubernetes Metrics Server etc. developed for [Trimaran: Real Load Aware Scheduling](https://github.com/kubernetes-sigs/scheduler-plugins/blob/master/kep/61-Trimaran-real-load-aware-scheduling/README.md) in Kubernetes.
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It stores the metrics in its local cache, which can be queried from scheduler plugins.
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The following metrics provider clients are currently supported:
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1) SignalFx
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2) Kubernetes Metrics Server
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3) Prometheus
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These clients fetch CPU usage currently, support for other resources will be added later as needed.
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# Tutorial
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This tutorial will guide you to build load watcher Docker image, which can be deployed to work with Trimaran scheduler plugins.
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The default `main.go` is configured to watch Kubernetes Metrics Server.
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You can change this to any available metrics provider in `pkg/metricsprovider`.
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To build a client for new metrics provider, you will need to implement `FetcherClient` interface.
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From the root folder, run the following commands to build docker image of load watcher, tag it and push to your docker repository:
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```
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docker build -t load-watcher:<version> .
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docker tag load-watcher:<version> <your-docker-repo>:<version>
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docker push <your-docker-repo>
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```
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Note that load watcher runs on default port 2020. Once deployed, you can use the following API to read watcher metrics:
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```
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GET /watcher
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```
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This will return metrics for all nodes. A query parameter to filter by host can be added with `host`.
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## Metrics Provider Configuration
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- By default Kubernetes Metrics Server client is configured. Set `KUBE_CONFIG` env var to your kubernetes client configuration file path if running out of cluster.
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- To use the Prometheus client, please configure environment variables `METRICS_PROVIDER_NAME`, `METRICS_PROVIDER_ADDRESS` and `METRICS_PROVIDER_TOKEN` to `Prometheus`, Prometheus address and auth token. Please do not set `METRICS_PROVIDER_TOKEN` if no authentication
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is needed to access the Prometheus APIs. Default value of address set is `http://prometheus-k8s:9090` for Prometheus client.
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- To use the SignalFx client, please configure environment variables `METRICS_PROVIDER_NAME`, `METRICS_PROVIDER_ADDRESS` and `METRICS_PROVIDER_TOKEN` to `SignalFx`, SignalFx address and auth token respectively. Default value of address set is `https://api.signalfx.com` for SignalFx client.
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## Deploy `load-watcher` as a service
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To deploy `load-watcher` as a monitoring service in your Kubernetes cluster, you should replace the values in the `[]` with your own cluster monitoring stack and then you can run the following.
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```bash
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> kubectl create -f manifests/load-watcher-deployment.yaml
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```
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## Using `load-watcher` client
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- `load-watcher-client.go` shows an example to use `load-watcher` packages as libraries in a client mode. When `load-watcher` is running as a
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service exposing an endpoint in a cluster, a client, such as Trimaran plugins, can use its libraries to create a client getting the latest metrics.
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