276 lines
10 KiB
Markdown
276 lines
10 KiB
Markdown
---
|
|
id: construct-workflow
|
|
title: Construct Workflow YAML without ChaosCenter
|
|
sidebar_label: Construct Workflow YAML
|
|
---
|
|
|
|
---
|
|
|
|
**Chaos Workflow** is a set of different operations coupled together to achieve desired chaos imapact on a Kubernetes Cluster. <br/>
|
|
A basic chaos workflow consists of these steps:
|
|
|
|
1. Install ChaosExperiment
|
|
2. Install ChaosEngine
|
|
3. Revert Chaos
|
|
|
|
## Before we begin
|
|
|
|
To construct a Chaos Workflow without ChaosCenter, make sure you are aware of [Chaos Workflow](../concepts/chaos-workflow.md), [ChaosEngine CR](../concepts/chaos-engine.md) and the different steps present in it.
|
|
|
|
## Steps to Construct a Chaos Workflow
|
|
|
|
LitmusChaos leverages the popular workflow and GitOps tool **Argo** to achieve this goal. Argo enables the orchestration of different chaos scenarios together in the form of workflow which is extremly simple and efficient to use.<br/>
|
|
|
|
The structure of a chaos workflow is similar to that of a Kubernetes Object. It consists of the mandatory fields like `apiVersion`, `kind`, `metadata`, `spec`.
|
|
|
|
Few additional terms in an Argo workflows are:
|
|
|
|
1. **Template** : It consists of different steps with their specific operations.
|
|
|
|
```yaml
|
|
templates:
|
|
- name: custom-chaos
|
|
steps:
|
|
- - name: install-chaos-experiments
|
|
template: install-chaos-experiments
|
|
- - name: pod-delete
|
|
template: pod-delete
|
|
- - name: revert-chaos
|
|
template: revert-chaos
|
|
```
|
|
|
|
2. **Steps** : It is a single step inside a workflow which runs a container based on the input parameters.
|
|
These can also be sequenced parallely.
|
|
|
|
```yaml
|
|
steps:
|
|
- - name: install-chaos-experiments
|
|
template: install-chaos-experiments
|
|
- - name: pod-delete
|
|
template: pod-delete
|
|
- name: pod-cpu-hog
|
|
template: pod-cpu-hog
|
|
- - name: revert-chaos
|
|
template: revert-chaos
|
|
```
|
|
|
|
3. **Entrypoint** : The first step that executes in a workflow is called its entrypoint.
|
|
|
|
```yaml
|
|
entrypoint: custom-chaos
|
|
```
|
|
|
|
Here, the template with the name `custom-chaos` will be executed first.
|
|
|
|
4. **Artifacts** : Artifacts are defined as the files saved by the containers in each step.
|
|
|
|
```yaml
|
|
- name: install-chaos-experiments
|
|
inputs:
|
|
artifacts:
|
|
- name: pod-delete
|
|
path: /tmp/pod-delete.yaml
|
|
raw:
|
|
data: >
|
|
apiVersion: litmuschaos.io/v1alpha1
|
|
|
|
description:
|
|
message: |...
|
|
```
|
|
|
|
Once the workflow is constructed, it should look like this:
|
|
|
|
```yaml
|
|
apiVersion: argoproj.io/v1alpha1
|
|
kind: Workflow
|
|
metadata:
|
|
name: pod-delete-experiment
|
|
namespace: litmus
|
|
spec:
|
|
arguments:
|
|
parameters:
|
|
- name: adminModeNamespace
|
|
value: litmus
|
|
entrypoint: custom-chaos
|
|
securityContext:
|
|
runAsNonRoot: true
|
|
runAsUser: 1000
|
|
serviceAccountName: argo-chaos
|
|
templates:
|
|
- name: custom-chaos
|
|
steps:
|
|
- - name: install-chaos-experiments
|
|
template: install-chaos-experiments
|
|
- - name: pod-delete
|
|
template: pod-delete
|
|
- - name: revert-chaos
|
|
template: revert-chaos
|
|
- name: install-chaos-experiments
|
|
inputs:
|
|
artifacts:
|
|
- name: pod-delete
|
|
path: /tmp/pod-delete.yaml
|
|
raw:
|
|
data: >
|
|
apiVersion: litmuschaos.io/v1alpha1
|
|
|
|
description:
|
|
message: |
|
|
Deletes a pod belonging to a deployment/statefulset/daemonset
|
|
kind: ChaosExperiment
|
|
|
|
metadata:
|
|
name: pod-delete
|
|
labels:
|
|
name: pod-delete
|
|
app.kubernetes.io/part-of: litmus
|
|
app.kubernetes.io/component: chaosexperiment
|
|
app.kubernetes.io/version: 1.13.8
|
|
spec:
|
|
definition:
|
|
scope: Namespaced
|
|
permissions:
|
|
- apiGroups:
|
|
- ""
|
|
- apps
|
|
- apps.openshift.io
|
|
- argoproj.io
|
|
- batch
|
|
- litmuschaos.io
|
|
resources:
|
|
- deployments
|
|
- jobs
|
|
- pods
|
|
- pods/log
|
|
- replicationcontrollers
|
|
- deployments
|
|
- statefulsets
|
|
- daemonsets
|
|
- replicasets
|
|
- deploymentconfigs
|
|
- rollouts
|
|
- pods/exec
|
|
- events
|
|
- chaosengines
|
|
- chaosexperiments
|
|
- chaosresults
|
|
verbs:
|
|
- create
|
|
- list
|
|
- get
|
|
- patch
|
|
- update
|
|
- delete
|
|
- deletecollection
|
|
image: litmuschaos/go-runner:1.13.8
|
|
imagePullPolicy: Always
|
|
args:
|
|
- -c
|
|
- ./experiments -name pod-delete
|
|
command:
|
|
- /bin/bash
|
|
env:
|
|
- name: TOTAL_CHAOS_DURATION
|
|
value: "15"
|
|
- name: RAMP_TIME
|
|
value: ""
|
|
- name: FORCE
|
|
value: "true"
|
|
- name: CHAOS_INTERVAL
|
|
value: "5"
|
|
- name: PODS_AFFECTED_PERC
|
|
value: ""
|
|
- name: LIB
|
|
value: litmus
|
|
- name: TARGET_PODS
|
|
value: ""
|
|
- name: SEQUENCE
|
|
value: parallel
|
|
labels:
|
|
name: pod-delete
|
|
app.kubernetes.io/part-of: litmus
|
|
app.kubernetes.io/component: experiment-job
|
|
app.kubernetes.io/version: 1.13.8
|
|
container:
|
|
args:
|
|
- kubectl apply -f /tmp/pod-delete.yaml -n
|
|
{{workflow.parameters.adminModeNamespace}} | sleep 30
|
|
command:
|
|
- sh
|
|
- -c
|
|
image: litmuschaos/k8s:latest
|
|
- name: pod-delete
|
|
inputs:
|
|
artifacts:
|
|
- name: pod-delete
|
|
path: /tmp/chaosengine-pod-delete.yaml
|
|
raw:
|
|
data: |
|
|
apiVersion: litmuschaos.io/v1alpha1
|
|
kind: ChaosEngine
|
|
metadata:
|
|
namespace: "{{workflow.parameters.adminModeNamespace}}"
|
|
generateName: pod-delete
|
|
labels:
|
|
instance_id: 86a4f130-d99b-4e91-b34b-8f9eee22cb63
|
|
spec:
|
|
appinfo:
|
|
appns: default
|
|
applabel: app=nginx
|
|
appkind: deployment
|
|
jobCleanUpPolicy: retain
|
|
engineState: active
|
|
chaosServiceAccount: litmus-admin
|
|
experiments:
|
|
- name: pod-delete
|
|
spec:
|
|
components:
|
|
env:
|
|
- name: TOTAL_CHAOS_DURATION
|
|
value: "30"
|
|
- name: CHAOS_INTERVAL
|
|
value: "10"
|
|
- name: FORCE
|
|
value: "false"
|
|
- name: PODS_AFFECTED_PERC
|
|
value: ""
|
|
container:
|
|
args:
|
|
- -file=/tmp/chaosengine-pod-delete.yaml
|
|
- -saveName=/tmp/engine-name
|
|
image: litmuschaos/litmus-checker:latest
|
|
- name: revert-chaos
|
|
container:
|
|
image: litmuschaos/k8s:latest
|
|
command:
|
|
- sh
|
|
- -c
|
|
args:
|
|
- "kubectl delete chaosengine -l 'instance_id in
|
|
(86a4f130-d99b-4e91-b34b-8f9eee22cb63, )' -n
|
|
{{workflow.parameters.adminModeNamespace}} "
|
|
```
|
|
|
|
## Install Experiment
|
|
|
|
1. ### ChaosExperiment CR:
|
|
|
|
The `install-experiment` step consists of ChaosExperiment CR in its artifact.
|
|
ChaosExperiment CR is the heart of LitmusChaos and contains the low-level execution information. They serve as off-the-shelf templates that one needs to "pull" (install on the cluster) before including them as part of chaos run against any target applications (the binding being defined in the ChaosEngine). The experiments are installed on the cluster as Kubernetes custom resources and are designed to hold granular details of the experiment such as image, library, necessary permissions, chaos parameters (set to their default values). Most of the ChaosExperiment parameters are essentially tunables that can be overridden from the ChaosEngine resource.
|
|
|
|
2. ### ChaosEngine CR:
|
|
The ChaosEngine is the main user-facing chaos custom resource with a namespace scope and is designed to hold information around how the chaos experiments are executed. It connects an application instance with one or more chaos experiments while allowing the users to specify run level details (override experiment defaults, provide new environment variables and volumes, options to delete or retain experiment pods, etc.,). This CR is also updated/patched with the status of the chaos experiments, making it the single source of truth with respect to the chaos.
|
|
|
|
## Resources
|
|
|
|
- The ChaosExperiment CR and ChaosEngine CR of different experiments are available at **[ChaosHub](http://hub.litmuschaos.io/)**.
|
|
|
|
<iframe width="560" height="315" src="https://www.youtube.com/embed/dan0AXO_soY?start=310" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
|
|
|
|
<iframe width="560" height="315" src="https://www.youtube.com/embed/xLjTx8lqTuQ?start=1163" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
|
|
|
|
## Learn More
|
|
|
|
- [What are the different Probes](../concepts/probes.md)
|
|
- [What is ChaosResult](../concepts/chaos-result.md)
|