## Introduction

- It can target random pods with a Spring Boot application and allows configuring the assaults to inject exceptions at runtime when the method is used. It tests the resiliency of the system when some applications are having unexpected faulty behavior.


!!! tip "Scenario: Inject exceptions to Spring Boot Application"    
    ![Spring Boot Exceptions](../../images/spring-boot-chaos.png)

## Uses

??? info "View the uses of the experiment" 
    coming soon

## Prerequisites

??? info "Verify the prerequisites" 
    <ul>
        <li> Ensure that Kubernetes Version > 1.16 </li>
        <li>Ensure that the Litmus Chaos Operator is running by executing <code>kubectl get pods</code> in operator namespace (typically, <code>litmus</code>).If not, install from <a href="https://v1-docs.litmuschaos.io/docs/getstarted/#install-litmus">here</a> </li>
        <li> Ensure that the <code> spring-boot-exceptions </code> experiment resource is available in the cluster by executing <code>kubectl get chaosexperiments</code> in the desired namespace. If not, install from <a href="https://hub.litmuschaos.io/api/chaos/master?file=faults/spring-boot/spring-boot-exceptions/fault.yaml">here</a></li>
        <li>Chaos Monkey Spring Boot dependency should be present in application. It can be enabled by two ways:
          <ol>
            <li>Add internal dependency inside the spring boot application
                <ol>
                    <li>Add Chaos Monkey for Spring Boot as dependency for your project
                        ```maven
                        <dependency>
                            <groupId>de.codecentric</groupId>
                            <artifactId>chaos-monkey-spring-boot</artifactId>
                            <version>2.6.1</version>
                        </dependency>
                        ```
                    </li>
                    <li> Start your Spring Boot App with the chaos-monkey spring profile enabled
                        ```bash
                        java -jar your-app.jar --spring.profiles.active=chaos-monkey --chaos.monkey.enabled=true
                        ```
                    </li>
                </ol> 
            </li>
            <li> Add as external dependency
                <ol>
                    <li>You can extend your existing application with the chaos-monkey and add it as an external dependency at startup, for this it is necessary to use the PropertiesLauncher of Spring Boot
                        ```maven
                        <dependency>
                            <groupId>de.codecentric</groupId>
                            <artifactId>chaos-monkey-spring-boot</artifactId>
                            <classifier>jar-with-dependencies</classifier>
                            <version>2.6.1</version>
                        </dependency>
                        ```
                    </li>
                    <li>Start your Spring Boot application, add Chaos Monkey for Spring Boot JAR and properties
                        ```bash
                        java -cp your-app.jar -Dloader.path=chaos-monkey-spring-boot-2.6.1-jar-with-dependencies.jar org.springframework.boot.loader.PropertiesLauncher --spring.profiles.active=chaos-monkey --spring.config.location=file:./chaos-monkey.properties
                        ```
                    </li>
                </ol>
            </li>
          </ol>
        </li>
    </ul>

## Default Validations

??? info "View the default validations" 
    - Spring boot pods are healthy before and after chaos injection

## Minimal RBAC configuration example (optional)

!!! tip "NOTE"   
    If you are using this experiment as part of a litmus workflow scheduled constructed & executed from chaos-center, then you may be making use of the [litmus-admin](https://litmuschaos.github.io/litmus/litmus-admin-rbac.yaml) RBAC, which is pre-installed in the cluster as part of the agent setup.

    ??? note "View the Minimal RBAC permissions"

        ```yaml
        apiVersion: v1
        kind: ServiceAccount
        metadata:
          name: spring-boot-exceptions-sa
          namespace: default
          labels:
            name: spring-boot-exceptions-sa
            app.kubernetes.io/part-of: litmus
        ---
        apiVersion: rbac.authorization.k8s.io/v1
        kind: Role
        metadata:
          name: spring-boot-exceptions-sa
          namespace: default
          labels:
            name: spring-boot-exceptions-sa
            app.kubernetes.io/part-of: litmus
        rules:
          # Create and monitor the experiment & helper pods
          - apiGroups: [""]
            resources: ["pods"]
            verbs: ["create","delete","get","list","patch","update", "deletecollection"]
          # Performs CRUD operations on the events inside chaosengine and chaosresult
          - apiGroups: [""]
            resources: ["events"]
            verbs: ["create","get","list","patch","update"]
          # Track and get the runner, experiment, and helper pods log 
          - apiGroups: [""]
            resources: ["pods/log"]
            verbs: ["get","list","watch"]
          # for creating and managing to execute commands inside target container
          - apiGroups: [""]
            resources: ["pods/exec"]
            verbs: ["get","list","create"]
          # for configuring and monitor the experiment job by the chaos-runner pod
          - apiGroups: ["batch"]
            resources: ["jobs"]
            verbs: ["create","list","get","delete","deletecollection"]
          # for creation, status polling and deletion of litmus chaos resources used within a chaos workflow
          - apiGroups: ["litmuschaos.io"]
            resources: ["chaosengines","chaosexperiments","chaosresults"]
            verbs: ["create","list","get","patch","update","delete"]
        ---
        apiVersion: rbac.authorization.k8s.io/v1
        kind: RoleBinding
        metadata:
          name: spring-boot-exceptions-sa
          namespace: default
          labels:
            name: spring-boot-exceptions-sa
            app.kubernetes.io/part-of: litmus
        roleRef:
          apiGroup: rbac.authorization.k8s.io
          kind: Role
          name: spring-boot-exceptions-sa
        subjects:
          - kind: ServiceAccount
            name: spring-boot-exceptions-sa
            namespace: default
        ```
        Use this sample RBAC manifest to create a chaosServiceAccount in the desired (app) namespace. This example consists of the minimum necessary role permissions to execute the experiment.

## Experiment tunables

??? info "check the experiment tunables"

    <h2>Mandatory Fields</h2>

    <table>
      <tr>
        <th> Variables </th>
        <th> Description </th>
        <th> Notes </th>
      </tr>
      <tr>
        <td> CM_PORT </td>
        <td> It contains port of the spring boot application </td>
        <td> </td>
      </tr>
    </table>
    
    <h2>Optional Fields</h2>

    <table>
      <tr>
        <th> Variables </th>
        <th> Description </th>
        <th> Notes </th>
      </tr>
      <tr>
        <td> CM_EXCEPTIONS_TYPE </td>
        <td> It contains type of raised exception </td>
        <td> Defaults value: <code> java.lang.IllegalArgumentException </code> </td>
      </tr>
       <tr>
        <td> CM_EXCEPTIONS_ARGUMENTS </td>
        <td> It contains argument of raised exception </td>
        <td> Defaults value: <code> java.lang.String:custom illegal argument exception </code> </td>
      </tr>
      <tr>
        <td> CM_LEVEL </td>
        <td> It contains number of requests are to be attacked, n value means nth request will be affected </td>
        <td> Defaults value: 1, it lies in [1,10000] range </td>
      </tr>
      <tr>
        <td> CM_WATCHED_CUSTOM_SERVICES </td>
        <td> It limits watched packages/classes/methods, it contains comma seperated list of fully qualified packages(class and/or method names)</td>
        <td> ByDefault it is empty list, which means it target all services </td>
      </tr>
      <tr>
        <td> CM_WATCHERS </td>
        <td> It contains comma separated list of watchers from the following watchers list [controller, restController, service, repository, component, webClient] </td>
        <td> ByDefault it is <code> restController </code></td>
      </tr>
      <tr>
        <td> TOTAL_CHAOS_DURATION </td>
        <td> The time duration for chaos injection (seconds) </td>
        <td> Defaults to 30 </td>
      </tr>
      <tr>
        <td> SEQUENCE </td>
        <td> It defines sequence of chaos execution for multiple target pods </td>
        <td> Default value: parallel. Supported: serial, parallel </td>
      </tr>
      <tr>
        <td> PODS_AFFECTED_PERC </td>
        <td> The Percentage of total pods to target  </td>
        <td> Defaults to 0% (corresponds to 1 replica) </td>
      </tr>
      <tr>
        <td> LIB </td>
        <td> The chaos lib used to inject the chaos </td>
        <td> Defaults to <code>litmus</code>. Supported <code>litmus</code> only </td>
      </tr>
      <tr>
        <td> RAMP_TIME </td>
        <td> Period to wait before and after injection of chaos in sec </td>
        <td> </td>
      </tr>
    </table>

## Experiment Examples

### Common Experiment Tunables

Refer the [common attributes](../common/common-tunables-for-all-experiments.md) and  [Spring Boot specific tunable](spring-boot-experiments-tunables.md) to tune the common tunables for all experiments and spring-boot specific tunables.

### Spring Boot Application Port

It tunes the spring-boot application port via `CM_PORT` ENV

Use the following example to tune this:

[embedmd]:# (./spring-boot-exceptions/target-port.yaml yaml)
```yaml
# kill spring-boot target application
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: spring-boot-chaos
  namespace: default
spec:
  appinfo:
    appns: 'default'
    applabel: 'app=spring-boot'
    appkind: 'deployment'
  # It can be active/stop
  engineState: 'active'
  chaosServiceAccount: spring-boot-exceptions-sa
  experiments:
    - name: spring-boot-exceptions
      spec:
        components:
          env:
            # port of the spring boot application
            - name: CM_PORT
              value: '8080'

```

### Exception Type and Arguments

Spring boot exception type and arguments can be tuned via `CM_EXCEPTIONS_TYPE` and `CM_EXCEPTIONS_ARGUMENTS` ENV

Use the following example to tune this:

[embedmd]:# (./spring-boot-exceptions/exception-type-and-args.yaml yaml)
```yaml
# provide the exception type and args
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: spring-boot-chaos
  namespace: default
spec:
  appinfo:
    appns: 'default'
    applabel: 'app=spring-boot'
    appkind: 'deployment'
  # It can be active/stop
  engineState: 'active'
  chaosServiceAccount: spring-boot-exceptions-sa
  experiments:
    - name: spring-boot-exceptions
      spec:
        components:
          env:
            # Type of raised exception
            - name: CM_EXCEPTIONS_TYPE
              value: 'java.lang.IllegalArgumentException'

             # Argument of the raised exception
            - name: CM_EXCEPTIONS_ARGUMENTS
              value: 'java.lang.String:custom illegal argument exception'

            # port of the spring boot application
            - name: CM_PORT
              value: '8080'
```