Project: Litmus (Observability and Analysis / Chaos Engineering)
File: pod-http-status-code.md

It injects http status code chaos inside the pod which modifies the status code of the response from the provided application server to desired status code provided by user on the service whose port is provided as `TARGETSERVICEPORT` by starting proxy server and then redirecting the traffic through the proxy server. It can test the application's resilience to error code http responses from the provided application server. !!! tip "Scenario: Modify http response status code of the HTTP request" ??? info "View the uses of the experiment" coming soon ??? info "Verify the prerequisites" Ensure that Kubernetes Version > 1.17 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> Ensure that the <code>pod-http-status-code</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/kubernetes/pod-http-status-code/fault.yaml">here</a> ??? info "View the default validations" The application pods should be in running state before and after chaos injection. !!! 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 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: pod-http-status-code-sa namespace: default labels: name: pod-http-status-code-sa app.kubernetes.io/part-of: litmus apiVersion: rbac.authorization.k8s.io/v1 kind: Role metadata: name: pod-http-status-code-sa namespace: default labels: name: pod-http-status-code-sa app.kubernetes.io/part-of: litmus rules: apiGroups: [""] resources: ["pods"] verbs: ["create","delete","get","list","patch","update", "deletecollection"] apiGroups: [""] resources: ["events"] verbs: ["create","get","list","patch","update"] apiGroups: [""] resources: ["configmaps"] verbs: ["get","list",] apiGroups: [""] resources: ["pods/log"] verbs: ["get","list","watch"] apiGroups: [""] resources: ["pods/exec"] verbs: ["get","list","create"] apiGroups: ["apps"] resources: ["deployments","statefulsets","replicasets", "daemonsets"] verbs: ["list","get"] apiGroups: ["apps.openshift.io"] resources: ["deploymentconfigs"] verbs: ["list","get"] apiGroups: [""] resources: ["replicationcontrollers"] verbs: ["get","list"] apiGroups: ["argoproj.io"] resources: ["rollouts"] verbs: ["list","get"] apiGroups: ["batch"] resources: ["jobs"] verbs: ["create","list","get","delete","deletecollection"] apiGroups: ["litmuschaos.io"] resources: ["chaosengines","chaosexperiments","chaosresults"] verbs: ["create","list","get","patch","update","delete"] apiVersion: rbac.authorization.k8s.io/v1 kind: RoleBinding metadata: name: pod-http-status-code-sa namespace: default labels: name: pod-http-status-code-sa app.kubernetes.io/part-of: litmus roleRef: apiGroup: rbac.authorization.k8s.io kind: Role name: pod-http-status-code-sa subjects: kind: ServiceAccount name: pod-http-status-code-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. ??? info "check the experiment tunables" <h2>Mandatory Fields</h2> <table> <tr> <th> Variables </th> <th> Description </th> <th> Notes </th> </tr> <tr> <td> TARGETSERVICEPORT </td> <td> Port of the service to target</td> <td>This should be the port on which the application container runs at the pod level, not at the service level. Defaults to port 80 </td> </tr> <tr> <td> STATUS_CODE </td> <td> Modified status code for the HTTP response</td> <td> If no value is provided, then a random value is selected from the list of supported values. Multiple values can be provided as comma separated, a random value from the provided list will be selected Supported values: [200, 201, 202, 204, 300, 301, 302, 304, 307, 400, 401, 403, 404, 500, 501, 502, 503, 504]. Defaults to random status code </td> </tr> <tr> <td> MODIFYRESPONSEBODY </td> <td> Whether to modify the body as per the status code provided.</td> <td> If true, then the body is replaced by a default template for the status

Defaults to true </td> </tr> </table> <h2>Optional Fields</h2> <table> <tr> <th> Variables </th> <th> Description </th> <th> Notes </th> </tr> <tr> <td> RESPONSE_BODY </td> <td> Body string to overwrite the http response body</td> <td> This will be used only if MODIFYRESPONSEBODY is set to true. If no value is provided, response will be an empty body. Defaults to empty body </td> </tr> <tr> <td> CONTENT_ENCODING </td> <td> Encoding type to compress/encodde the response body </td> <td> Accepted values are: gzip, deflate, br, identity. Defaults to none (no encoding) </td> </td> <tr> <td> CONTENT_TYPE </td> <td> Content type of the response body </td> <td> Defaults to text/plain </td> </tr> <tr> <td> PROXY_PORT </td> <td> Port where the proxy will be listening for requests</td> <td> Defaults to 20000 </td> </tr> <tr> <td> NETWORK_INTERFACE </td> <td> Network interface to be used for the proxy</td> <td> Defaults to `eth0` </td> </tr> <tr> <td> TOXICITY </td> <td> Percentage of HTTP requests to be affected </td> <td> Defaults to 100 </td> </tr> <tr> <td> CONTAINER_RUNTIME </td> <td> container runtime interface for the cluster</td> <td> Defaults to containerd, supported values: docker, containerd and crio for litmus and only docker for pumba LIB </td> </tr> <tr> <td> SOCKET_PATH </td> <td> Path of the containerd/crio/docker socket file </td> <td> Defaults to `/run/containerd/containerd.sock` </td> </tr> <tr> <td> TOTALCHAOSDURATION </td> <td> The duration of chaos injection (seconds) </td> <td> Default (60s) </td> </tr> <tr> <td> TARGET_PODS </td> <td> Comma separated list of application pod name subjected to pod http status code chaos</td> <td> If not provided, it will select target pods randomly based on provided appLabels</td> </tr> <tr> <td> PODSAFFECTEDPERC </td> <td> The Percentage of total pods to target </td> <td> Defaults to 0 (corresponds to 1 replica), provide numeric value only </td> </tr> <tr> <td> LIB_IMAGE </td> <td> Image used to run the netem command </td> <td> Defaults to `litmuschaos/go-runner:latest` </td> </tr> <tr> <td> RAMP_TIME </td> <td> Period to wait before and after injection of chaos in sec </td> <td> </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> </table> Refer the and to tune the common tunables for all experiments and pod specific tunables. It defines the port of the targeted service that is being targeted. It can be tuned via `TARGETSERVICEPORT` ENV. This should be the port where the application runs at the pod level, not at the service level. This means if the application pod is running the service at port 8080 and we create a service exposing that at port 80, then the target service port should be 8080 and not 80, which is the port at pod-level. Use the following example to tune this: ```yaml apiVersion: litmuschaos.io/v1alpha1 kind: ChaosEngine metadata: name: engine-nginx spec: engineState: "active" annotationCheck: "false" appinfo: appns: "default" applabel: "app=nginx" appkind: "deployment" chaosServiceAccount: pod-http-status-code-sa experiments: name: pod-http-status-code spec: components: env: name: TARGETSERVICEPORT value: "80" name: STATUS_CODE value: '500' ``` It defines the port on which the proxy server will listen for requests. It can be tuned via `PROXY_PORT` ENV. Use the following example to tune this: ```yaml apiVersion:

kind: ChaosEngine metadata: name: engine-nginx spec: engineState: "active" annotationCheck: "false" appinfo: appns: "default" applabel: "app=nginx" appkind: "deployment" chaosServiceAccount: pod-http-status-code-sa experiments: name: pod-http-status-code spec: components: env: name: PROXY_PORT value: '8080' name: TARGETSERVICEPORT value: "80" name: STATUS_CODE value: '500' ``` It defines the status code value for the http response. It can be tuned via `STATUS_CODE` ENV. Use the following example to tune this: ```yaml apiVersion: litmuschaos.io/v1alpha1 kind: ChaosEngine metadata: name: engine-nginx spec: engineState: "active" annotationCheck: "false" appinfo: appns: "default" applabel: "app=nginx" appkind: "deployment" chaosServiceAccount: pod-http-status-code-sa experiments: name: pod-http-status-code spec: components: env: name: STATUS_CODE value: '500' name: TARGETSERVICEPORT value: "80" ``` It defines whether to modify the respone body with a pre-defined template to match with the status code value of the http response. It can be tuned via `MODIFYRESPONSEBODY` ENV. Use the following example to tune this: ```yaml apiVersion: litmuschaos.io/v1alpha1 kind: ChaosEngine metadata: name: engine-nginx spec: engineState: "active" annotationCheck: "false" appinfo: appns: "default" applabel: "app=nginx" appkind: "deployment" chaosServiceAccount: pod-http-status-code-sa experiments: name: pod-http-status-code spec: components: env: name: "MODIFYRESPONSEBODY" value: "true" name: STATUS_CODE value: '500' name: TARGETSERVICEPORT value: "80" ``` It defines the toxicity value to be added to the http request. It can be tuned via `TOXICITY` ENV. Toxicity value defines the percentage of the total number of http requests to be affected. Use the following example to tune this: ```yaml apiVersion: litmuschaos.io/v1alpha1 kind: ChaosEngine metadata: name: engine-nginx spec: engineState: "active" annotationCheck: "false" appinfo: appns: "default" applabel: "app=nginx" appkind: "deployment" chaosServiceAccount: pod-http-status-code-sa experiments: name: pod-http-status-code spec: components: env: name: TOXICITY value: "100" name: TARGETSERVICEPORT value: "80" ``` It defines the body string that will overwrite the http response body. It can be tuned via `RESPONSEBODY` and `MODIFYRESPONSE_BODY` ENV. The `MODIFYRESPONSEBODY` ENV should be set to `true` to enable this feature. Use the following example to tune this: ```yaml apiVersion: litmuschaos.io/v1alpha1 kind: ChaosEngine metadata: name: engine-nginx spec: engineState: "active" annotationCheck: "false" appinfo: appns: "default" applabel: "app=nginx" appkind: "deployment" chaosServiceAccount: pod-http-status-code-sa experiments: name: pod-http-status-code spec: components: env: name: RESPONSE_BODY value: '<h1>Hello World</h1>' name: "MODIFYRESPONSEBODY" value: "true" name: STATUS_CODE value: '500' name: TARGETSERVICEPORT value: "80" ``` It defines the content encoding and content type of the response body. It can be tuned via `CONTENTENCODING` and `CONTENTTYPE` ENV. Use the following example to tune this: ```yaml apiVersion: litmuschaos.io/v1alpha1 kind: ChaosEngine metadata: name: engine-nginx spec: engineState: "active" annotationCheck: "false" appinfo: appns: "default" applabel: "app=nginx" appkind: "deployment" chaosServiceAccount: pod-http-status-code-sa experiments: name: pod-http-status-code spec: components: env: name: CONTENT_ENCODING value: 'gzip' name: CONTENT_TYPE value: 'text/html' name: "MODIFYRESPONSEBODY" value: "true" name: STATUS_CODE value: '500' name: TARGETSERVICEPORT value: "80" ``` It defines the network interface to be used for the proxy. It can be tuned via `NETWORK_INTERFACE` ENV. Use the following example to tune this: ```yaml apiVersion: litmuschaos.io/v1alpha1 kind: ChaosEngine metadata: name: engine-nginx spec: engineState: "active" annotationCheck: "false" appinfo: appns: "default" applabel: "app=nginx" appkind: "deployment" chaosServiceAccount: pod-http-status-code-sa experiments: name: pod-http-status-code spec: components: env: name: NETWORK_INTERFACE value: "eth0" name: TARGETSERVICEPORT value: '80' name: STATUS_CODE value: '500' ``` It defines the `CONTAINERRUNTIME` and `SOCKETPATH` ENV to set the container runtime and socket file path. `CONTAINER_RUNTIME`: It supports `docker`, `containerd`, and `crio` runtimes. The default value is `docker`. `SOCKET_PATH`: It contains path of docker socket file by default(`/run/containerd/containerd.sock`). For other runtimes provide the appropriate path. Use the following example to tune this: ```yaml apiVersion: litmuschaos.io/v1alpha1 kind: ChaosEngine metadata: name: engine-nginx spec: engineState: "active" annotationCheck: "false" appinfo: appns: "default" applabel: "app=nginx" appkind: "deployment" chaosServiceAccount: pod-http-status-code-sa experiments: name: pod-http-status-code spec: components: env: name: CONTAINER_RUNTIME value: 'containerd' name: SOCKET_PATH value: '/run/containerd/containerd.sock' name: TARGETSERVICEPORT value: "80" name: STATUS_CODE value: '500' ```