CHAOS-5571 Redis cache penetration

docs/chaos-engineering/chaos-faults/linux/linux-redis-cache-penetration.md

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+---
+id: linux-redis-cache-penetration
+title: Linux Redis cache penetration
+---
+
+import Ossupport from './shared/note-supported-os.md'
+import FaultPermissions from './shared/fault-permissions.md'
+import AuthenticationDetails from './shared/redis-auth.md'
+
+Linux Redis cache penetration continuously sends cache requests to the Redis database to find the value for a non-existing key. This continuous request reduces the performance of the application.
+
+![Linux Redis cache penetration](./static/images/linux-redis-cache-penetration.png)
+
+## Use cases
+- Slows down the database for responses to other requests.
+- Determines the resilience of Redis-dependant application when cache requests are continuously sent to a Redis database and they result in a cache miss.
+
+<Ossupport />
+
+<FaultPermissions />
+
+<AuthenticationDetails />
+
+### External packages
+This fault uses [`stress-ng`](https://github.com/ColinIanKing/stress-ng), which is installed as part of the infrastructure installation.
+
+### Optional tunables
+
+<table>
+  <tr>
+    <th> Tunable </th>
+    <th> Description </th>
+    <th> Notes </th>
+  </tr>
+  <tr>
+    <td> requestCount </td>
+    <td> Number of times to try to penetrate the Redis cache. </td>
+    <td> Default: 1000. For more information, go to <a href="#number-of-requests"> request count. </a></td>
+  </tr>
+  <tr>
+    <td> duration </td>
+    <td> Duration through which chaos is injected into the target resource. Should be provided in <code>[numeric-hours]h[numeric-minutes]m[numeric-seconds]s</code> format. </td>
+    <td> Default: <code>30s</code>. Examples: <code>1m25s</code>, <code>1h3m2s</code>, <code>1h3s</code>. For more information, go to <a href="/docs/chaos-engineering/chaos-faults/common-tunables-for-all-faults#duration-of-the-chaos">duration.</a></td>
+  </tr>
+  <tr>
+    <td> rampTime </td>
+    <td> Period to wait before and after injecting chaos. Should be provided in <code>[numeric-hours]h[numeric-minutes]m[numeric-seconds]s</code> format. </td>
+    <td> Default: <code>0s</code>. Examples: <code>1m25s</code>, <code>1h3m2s</code>, <code>1h3s</code>. For more information, go to <a href="/docs/chaos-engineering/chaos-faults/common-tunables-for-all-faults#ramp-time">ramp time</a>. </td>
+  </tr>
+</table>
+
+### Number of requests
+
+The `requestCount` input variable indicates the number of times to penetrate the Redis cache. Its default value is 1000.
+
+The following YAML snippet illustrates the use of this input variable:
+
+[embedmd]:# (./static/manifests/linux-redis-cache-penetration/requests.yaml yaml)
+```yaml
+apiVersion: litmuchaos.io/v1alpha1
+kind: LinuxFault
+metadata:
+  name: redis-cache-penetration
+  labels:
+    name: cache-penetration
+spec:
+  redisChaos/inputs:
+    duration: 30s
+    requestCount: 1000
+    rampTime: ""
+```

docs/chaos-engineering/chaos-faults/linux/shared/redis-auth.md

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+## Redis authentication
+The following authentication and connection details reside on the same machine where the chaos infrastructure is executed. These details are provided in the `/etc/linux-chaos-infrastructure/redis.env` file in the following format:
+
+```
+ADDRESS="/path/to/redis/server"
+PASSWORD="password"
+TLS_AUTH_CERT="/path/tp/tls-cert"
+```
+
+:::tip
+`PASSWORD` and `TLS_AUTH_CERT` are optional, whereas `ADDRESS` is a mandatory field. You need them only if you have configured your Redis database to facilitate it.
+:::
+
+
+| **ENV name**  | **Description**                                                | **Example**                |
+|---------------|----------------------------------------------------------------|----------------------------|
+| ADDRESS       | Location where the Redis server is running.                    | `https://redis-server.com` |
+| PASSWORD      | Password to connect to the Redis database.                     | `password`                 |
+| TLS_AUTH_CERT | File path to the location where the TLS certificate is stored. | `/path/to/file`            |

docs/chaos-engineering/chaos-faults/linux/static/manifests/linux-redis-cache-penetration/requests.yaml

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+apiVersion: litmuchaos.io/v1alpha1
+kind: LinuxFault
+metadata:
+  name: redis-cache-penetration
+  labels:
+    name: cache-penetration
+spec:
+  redisChaos/inputs:
+    duration: 30s
+    requestCount: 1000
+    rampTime: ""