mirror of
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126 lines
8.0 KiB
Markdown
126 lines
8.0 KiB
Markdown
# node-problem-detector
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[](https://travis-ci.org/kubernetes/node-problem-detector) [](https://goreportcard.com/report/github.com/kubernetes/node-problem-detector)
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node-problem-detector aims to make various node problems visible to the upstream
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layers in cluster management stack.
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It is a daemon which runs on each node, detects node
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problems and reports them to apiserver.
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node-problem-detector can either run as a
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[DaemonSet](http://kubernetes.io/docs/admin/daemons/) or run standalone.
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Now it is running as a
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[Kubernetes Addon](https://github.com/kubernetes/kubernetes/tree/master/cluster/addons)
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enabled by default in the GCE cluster.
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# Background
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There are tons of node problems could possibly affect the pods running on the
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node such as:
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* Infrastructure daemon issues: ntp service down;
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* Hardware issues: Bad cpu, memory or disk, ntp service down;
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* Kernel issues: Kernel deadlock, corrupted file system;
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* Container runtime issues: Unresponsive runtime daemon;
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* ...
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Currently these problems are invisible to the upstream layers in cluster management
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stack, so Kubernetes will continue scheduling pods to the bad nodes.
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To solve this problem, we introduced this new daemon **node-problem-detector** to
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collect node problems from various daemons and make them visible to the upstream
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layers. Once upstream layers have the visibility to those problems, we can discuss the
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remedy system.
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# Problem API
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node-problem-detector uses `Event` and `NodeCondition` to report problems to
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apiserver.
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* `NodeCondition`: Permanent problem that makes the node unavailable for pods should
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be reported as `NodeCondition`.
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* `Event`: Temporary problem that has limited impact on pod but is informative
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should be reported as `Event`.
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# Problem Daemon
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A problem daemon is a sub-daemon of node-problem-detector. It monitors a specific
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kind of node problems and reports them to node-problem-detector.
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A problem daemon could be:
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* A tiny daemon designed for dedicated usecase of Kubernetes.
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* An existing node health monitoring daemon integrated with node-problem-detector.
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Currently, a problem daemon is running as a goroutine in the node-problem-detector
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binary. In the future, we'll separate node-problem-detector and problem daemons into
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different containers, and compose them with pod specification.
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List of supported problem daemons:
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| Problem Daemon | NodeCondition | Description |
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|----------------|:---------------:|:------------|
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| [KernelMonitor](https://github.com/kubernetes/node-problem-detector/blob/master/config/kernel-monitor.json) | KernelDeadlock | A system log monitor monitors kernel log and reports problem according to predefined rules. |
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| [AbrtAdaptor](https://github.com/kubernetes/node-problem-detector/blob/master/config/abrt-adaptor.json) | None | Monitor ABRT log messages and report them further. ABRT (Automatic Bug Report Tool) is health monitoring daemon able to catch kernel problems as well as application crashes of various kinds occurred on the host. For more information visit the [link](https://github.com/abrt). |
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| [CustomPluginMonitor](https://github.com/kubernetes/node-problem-detector/blob/master/config/custom-plugin-monitor.json) | On-demand(According to users configuration) | A custom plugin monitor for node-problem-detector to invoke and check various node problems with user defined check scripts. See proposal [here](https://docs.google.com/document/d/1jK_5YloSYtboj-DtfjmYKxfNnUxCAvohLnsH5aGCAYQ/edit#). |
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# Usage
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## Flags
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* `--version`: Print current version of node-problem-detector.
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* `--address`: The address to bind the node problem detector server.
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* `--port`: The port to bind the node problem detector server. Use 0 to disable.
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* `--system-log-monitors`: List of paths to system log monitor configuration files, comma separated, e.g.
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[config/kernel-monitor.json](https://github.com/kubernetes/node-problem-detector/blob/master/config/kernel-monitor.json).
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Node problem detector will start a separate log monitor for each configuration. You can
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use different log monitors to monitor different system log.
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* `--custom-plugin-monitors`: List of paths to custom plugin monitor config files, comma separated, e.g.
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[config/custom-plugin-monitor.json](https://github.com/kubernetes/node-problem-detector/blob/master/config/custom-plugin-monitor.json).
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Node problem detector will start a separate custom plugin monitor for each configuration. You can
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use different custom plugin monitors to monitor different node problems.
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* `--apiserver-override`: A URI parameter used to customize how node-problem-detector
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connects the apiserver. The format is same as the
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[`source`](https://github.com/kubernetes/heapster/blob/master/docs/source-configuration.md#kubernetes)
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flag of [Heapster](https://github.com/kubernetes/heapster).
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For example, to run without auth, use the following config:
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```
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http://APISERVER_IP:APISERVER_PORT?inClusterConfig=false
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```
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Refer [heapster docs](https://github.com/kubernetes/heapster/blob/master/docs/source-configuration.md#kubernetes) for a complete list of available options.
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* `--hostname-override`: A customized node name used for node-problem-detector to update conditions and emit events. node-problem-detector gets node name first from `hostname-override`, then `NODE_NAME` environment variable and finally fall back to `os.Hostname`.
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## Build Image
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* `go get` or `git clone` node-problem-detector repo into `$GOPATH/src/k8s.io` or `$GOROOT/src/k8s.io`
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with one of the below directions:
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* `cd $GOPATH/src/k8s.io && git clone git@github.com:kubernetes/node-problem-detector.git`
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* `cd $GOROOT/src/k8s.io && git clone git@github.com:kubernetes/node-problem-detector.git`
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* `cd $GOPATH/src/k8s.io && go get k8s.io/node-problem-detector`
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* run `make` in the top directory. It will:
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* Build the binary.
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* Build the docker image. The binary and `config/` are copied into the docker image.
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**Note**:
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By default node-problem-detector will be built with systemd support with `make` command. This requires systemd develop files.
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You should download the systemd develop files first. For Ubuntu, `libsystemd-journal-dev` package should
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be installed. For Debian, `libsystemd-dev` package should be installed.
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## Push Image
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`make push` uploads the docker image to registry. By default, the image will be uploaded to
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`staging-k8s.gcr.io`. It's easy to modify the `Makefile` to push the image
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to another registry.
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## Start DaemonSet
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* Edit [node-problem-detector.yaml](https://github.com/kubernetes/node-problem-detector/blob/master/deployment/node-problem-detector.yaml) to fit your environment: Set `log` volume to your system log directory. (Used by SystemLogMonitor). For **kubernetes <1.9** use [node-problem-detector-old.yaml](https://github.com/kubernetes/node-problem-detector/blob/master/deployment/node-problem-detector-old.yaml)
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* Create the DaemonSet with `kubectl create -f node-problem-detector.yaml`
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* If needed, you can use [ConfigMap](https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-configmap/)
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to overwrite the `config/`.
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## Start Standalone
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To run node-problem-detector standalone, you should set `inClusterConfig` to `false` and
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teach node-problem-detector how to access apiserver with `apiserver-override`.
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To run node-problem-detector standalone with an insecure apiserver connection:
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```
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node-problem-detector --apiserver-override=http://APISERVER_IP:APISERVER_INSECURE_PORT?inClusterConfig=false
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```
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For more scenarios, see [here](https://github.com/kubernetes/heapster/blob/master/docs/source-configuration.md#kubernetes)
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# Links
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* [Design Doc](https://docs.google.com/document/d/1cs1kqLziG-Ww145yN6vvlKguPbQQ0psrSBnEqpy0pzE/edit?usp=sharing)
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* [Slides](https://docs.google.com/presentation/d/1bkJibjwWXy8YnB5fna6p-Ltiy-N5p01zUsA22wCNkXA/edit?usp=sharing)
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* [Plugin Interface Proposal](https://docs.google.com/document/d/1jK_5YloSYtboj-DtfjmYKxfNnUxCAvohLnsH5aGCAYQ/edit#)
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* [Addon Manifest](https://github.com/kubernetes/kubernetes/tree/master/cluster/addons/node-problem-detector)
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