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Redis cache penetration

Redis cache penetration fault continuously sends cache requests to the Redis database to find the value for a key that does not exist. This continuous request reduces the performance of the application.

Pod Redis cache penetration

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.

Redis authentication​

note

If your Redis server doesn't require authentication, you can directly provide the ADDRESS tunable, that refers to the Redis server address. Refer here.

If your application requires a secret or authentication, provide the ADDRESS, PASSWORD and the TLS authentication certificate. Create a Kubernetes secret (say redis-secret) in the namespace where the fault executes. A sample is shown below.

apiVersion: v1
kind: Secret
metadata:
  name: redis-secret  # Name of the Secret
type: Opaque       # Default Secret type
stringData:
  redis-secret.yaml: |-
    address: 34.136.111.6:6379
    password: mypass
    tlsCertFile: <cert>

After creating the secret, mount the secret into the experiment, and reference the mounted file path using the SECRET_FILE_PATH environment variable in the experiment manifest. A sample is shown below.

apiVersion: litmuschaos.io/v1alpha1
kind: K8sFault
metadata:
  name: redis-cache-penetration
spec:
  definition:
    chaos:
      env:
        ...  # other env
        ...  # other env
        - name: SECRET_FILE_PATH
          value: "/tmp/redis-secret.yaml"
      components:
        secrets:   # Kubernetes secret mounted
          - name: redis-secret
            mountPath: /tmp/

Optional tunables​

Tunable Description Notes
TOTAL_CHAOS_DURATION Duration through which chaos is injected into the target resource. Should be provided in [numeric-hours]h[numeric-minutes]m[numeric-seconds]s format. Default: 30s. Examples: 1m25s, 1h3m2s, 1h3s. For more information, go to duration.
RAMP_TIME Period to wait before and after injecting chaos. Should be provided in [numeric-hours]h[numeric-minutes]m[numeric-seconds]s format. Default: 0s. Examples: 1m25s, 1h3m2s, 1h3s. For more information, go to ramp time.
ADDRESS The address of the Redis server. If your Redis server doesn't require authentication, directly provide the address.
REQUEST_COUNT Number of requests to be sent for accessing the cache. Default: 1000.
SECRET_FILE_PATH Path to the file that contains the secret. If a password or certificate is required alongside the address, use the secret file approach.

Parameters​

The following YAML snippet illustrates the use of these tunables:

apiVersion: litmuchaos.io/v1alpha1
kind: K8sFault
metadata:
  name: redis-cache-penetration
      env:
        - name: TOTAL_CHAOS_DURATION
          value: "60" # in seconds
        ## Period to wait before and after injection of chaos in sec
        - name: RAMP_TIME
          value: ""
        - name: ADDRESS
          value: ""
        - name: REQUEST_COUNT
          value: "1000"
        - name: SECRET_FILE_PATH   # optional- required only for authentication
          value: "/tmp/redis-secret.yaml"