docs: add document for dns chaos (kubernetes#3)

Signed-off-by: xiang <[email protected]>

Co-authored-by: Calvin Weng <[email protected]>

docs/chaos_experiments/dns_chaos.md

@@ -0,0 +1,71 @@
+---
+id: dnschaos_experiment
+title: DNSChaos Experiment
+sidebar_label: DNSChaos Experiment
+---
+
+This document describes how to create DNSChaos experiments in Chaos Mesh.
+
+DNSChaos allows you to simulate fault DNS responses such as a DNS error or a random IP address after a request is sent.
+
+## Deploy DNS service for chaos
+
+To create DNSChaos experiments in Chaos Mesh, you need to deploy a DNS service in Chaos Mesh by executing the command below:
+
+```bash
+helm upgrade chaos-mesh helm/chaos-mesh --namespace=chaos-testing --set dnsServer.create=true
+```
+
+When the deployment finishes, check the status of this DNS service:
+
+```bash
+kubectl get pods -n chaos-testing -l app.kubernetes.io/component=chaos-dns-server
+```
+
+Make sure the Pod's `STATUS` is `Running`.
+
+## Configuration file
+
+Below is a sample DNSChaos configuration file:
+
+```yaml
+apiVersion: chaos-mesh.org/v1alpha1
+kind: DNSChaos
+metadata:
+  name: busybox-dns-chaos
+spec:
+  action: random
+  scope: inner
+  mode: all
+  selector:
+    namespaces:
+      - busybox
+  duration: "90s"
+  scheduler:
+    cron: "@every 100s"
+```
+
+For more sample files, see [examples](https://github.com/chaos-mesh/chaos-mesh/tree/master/examples). You can edit them as needed.
+
+## Fields description
+
+- **action**: Defines the chaos action for DNS chaos. Supported actions are:
+    - `error` - Get an error when sending the DNS request
+    - `random` - Get a random IP when sending the DNS request
+
+* **scope**: Defines the scope of the DNS chaos. Supported scopes are:
+    - `outer` - DNS chaos only works on outer hosts of the Kubernetes cluster
+    - `inner`- DNS chaos only works on inner hosts of the Kubernetes cluster
+    - `all` - DNS chaos works on all hosts.
+
+* **selector**: Specifies the target pods for chaos injection. For more details, see [Define the Scope of Chaos Experiment](../user_guides/experiment_scope.md).
+
+
+## Notes
+
+- Currently, DNSChaos only supports record types `A` and `AAAA`.
+- The chaos DNS service runs CoreDNS with the  [k8s_dns_chaos](https://github.com/chaos-mesh/k8s_dns_chaos) plugin. If the CoreDNS service in your Kubernetes cluster contains some special configurations, you can edit configMap `dns-server-config` to make the configuration of the chaos DNS service consistent with that of the K8s CoreDNS service as shown below:
+
+    ```bash
+    kubectl edit configmap dns-server-config -n chaos-testing
+    ```

sidebars.js

@@ -37,6 +37,7 @@ module.exports = {
         'chaos_experiments/timechaos_experiment',
         'chaos_experiments/iochaos_experiment',
         'chaos_experiments/kernelchaos_experiment',
+        'chaos_experiments/dnschaos_experiment',
       ],
     },
     {