Pod JVM Mongo Exception

Pod JVM Mongo Exception fault simulates MongoDB calls failures by raising exceptions for db calls executed by the Java process running inside a Kubernetes pod. This helps test the application's behavior and resilience against database-related errors.

tip

JVM chaos faults use the Byteman utility to inject chaos faults into the JVM.

Use cases

Pod JVM Mongo exception:

• Validate the application's resilience by simulating MongoDB exceptions to ensure it can recover gracefully, retry operations, or switch to backup databases without affecting functionality.
• Assess if the monitoring systems and alerting mechanisms can accurately detect and report db exceptions in real-time.
• Trigger exception-handling paths in the application to ensure coverage of edge cases related to db query failures during testing.

Mandatory tunables

Tunable	Description	Notes
DATABASE	The name of the mongodb database to be targeted.	For more information, go to Parameters
COLLECTION	The name of the mongodb collection to be targeted.	For more information, go to Parameters
METHOD	The name of the mongodb method to be targeted.	For more information, go to Parameters
EXCEPTION_CLASS	The name of the exception class.	For more information, go to Parameters
EXCEPTION_MESSAGE	The exception message to be raised.	For more information, go to Parameters

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 of the chaos.
TRANSACTION_PERCENTAGE	The percentage of total mongodb calls to be targeted.	Supports percentage in (0.00,1.00] range. If not provided, it targets all mongodb queries. For more information, go to Parameters
POD_AFFECTED_PERCENTAGE	Percentage of total pods to target. Provide numeric values.	Default: 0 (corresponds to 1 replica). For more information, go to pods affected percentage.
JAVA_HOME	Path to the Java installation directory.	For example, /tmp/dir/jdk.
BYTEMAN_PORT	Port used by the Byteman agent.	Default: 9091.
CONTAINER_RUNTIME	Container runtime interface for the cluster.	Default: containerd. Support values: docker, containerd and crio. For more information, go to container runtime.
SOCKET_PATH	Path of the containerd or crio or docker socket file.	Default: /run/containerd/containerd.sock. For more information, go to socket path.
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.
SEQUENCE	Sequence of chaos execution for multiple target pods.	Default: parallel. Supports serial and parallel. For more information, go to sequence of chaos execution.
TARGET_CONTAINER	Name of the container subject to API header modification.	None. For more information, go to target specific container
TARGET_PODS	Comma-separated list of application pod names subject to pod HTTP modify body.	If not provided, the fault selects target pods randomly based on provided appLabels. For more information, go to target specific pods.
NODE_LABEL	It filters the target pods that are scheduled on nodes matching the specified NODE_LABEL.	For more information, go to node label.
LIB_IMAGE	Image used to inject chaos.	Default: harness/ddcr-faults:main-latest. For more information, go to image used by the helper pod.

Parameters

The following YAML snippet illustrates the use of these tunables:

kind: KubernetesChaosExperiment
apiVersion: litmuschaos.io/v1alpha1
metadata:
  name: pod-jvm-mongo-exception
  namespace: hce
spec:
  tasks:
    - definition:
        chaos:
          env:
            - name: TOTAL_CHAOS_DURATION
              value: "60"
            # name of the mongodb database to be targeted
            - name: DATABASE
              value: "library"
            # name of the mongodb collection to be targeted
            - name: COLLECTION
              value: "books"
            # name of the mongodb method to be targeted
            - name: METHOD
              value: "find"
            # name of the exception class
            - name: EXCEPTION_CLASS
              value: "IllegalArgumentException"
            # provide the exception message
            - name: EXCEPTION_MESSAGE
              value: "CHAOS BOOM!"
            # provide the transaction percentage
            - name: TRANSACTION_PERCENTAGE
              value: "50"