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Basic Usage Guide

This docs focuses on how to make Kruise Rollout effective and how to make a complete release, and answer some questions about usages.

Note: v1beta1 available from Kruise Rollout v0.5.0.

A Complete Release Process​

Step 0: Requirements​

  • Install Kruise Rollouts.

  • Assume that you already have a Deployment in your Kubernetes cluster as follows:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: workload-demo
  namespace: default
spec:
  replicas: 10
  selector:
    matchLabels:
      app: demo
  template:
    metadata:
      labels:
        app: demo
    spec:
      containers:
      - name: busybox
        image: busybox:latest
        command: ["/bin/sh", "-c", "sleep 100d"]
        env:
        - name: VERSION
          value: "version-1"

Step 1: Prepare and apply Rollout configuration​

Assume that you want to use multi-batch update strategy to upgrade your Deployment from "version-1" to "version-2":

  • In the 1-st batch: Only 1 Pod should be upgraded;
  • In the 2-nd batch: 50% Pods should be upgraded, i.e., 5 updated Pods;
  • In the 3-rd batch: 100% Pods should be upgradedm i.e., 10 updated Pods.
$ kubectl apply -f - <<EOF
apiVersion: rollouts.kruise.io/v1beta1
kind: Rollout
metadata:
  name: rollouts-demo
  namespace: default
spec:
  workloadRef:
    apiVersion: apps/v1
    kind: Deployment
    name: workload-demo
  strategy:
    canary:
      steps:
      - replicas: 1
      - replicas: 50%
      - replicas: 100%
EOF

Step 2: Upgrade Deployment to "version-2" and release the 1-st batch​

$ kubectl patch deployment workload-demo -p \
'{"spec":{"template":{"spec":{"containers":[{"name":"busybox", "env":[{"name":"VERSION", "value":"version-2"}]}]}}}}'

Wait a while, we will see the Deployment status show Only 1 Pod is upgraded.

Step 3: Continue to release the 2-nd batch​

$ kubectl-kruise rollout approve rollout/rollouts-demo -n default

Note: kubectl-kruise is also provided by OpenKruise community.

Wait a while, we will see the Deployment status show 5 Pod is upgraded.

Step 4: Continue to release the 3-rd batch​

$ kubectl-kruise rollout approve rollout/rollouts-demo -n default

Wait a while, we will see the Deployment status show all 10 Pod is upgraded.

How to continue the next step manually?​

Currently, there are two methods. For example, if you have completed the first batch and want to send the second batch:

  • Method one: You can set the pause.duration field of the first batch to duration:0, which will automatically enter the next batch.
  • Method two: You can update the rollout.status.canaryStatus.currentStepState field to "StepReady", which will also automatically enter the next batch.

Each method has its own advantages and disadvantages:

  • For method one, it can ensure the idempotence of your operation, but you need to reset the strategy of the rollout back to its original state (e.g., reset the duration field to nil) before the next release.
kind: Rollout
spec:
  strategy:
    canary:
      steps:
      - replicas: 1
        pause:
          duration: 0
      - ... ...
  • For method two, you don't need to change anything before the next release. However, before confirming, you need to check the status of Rollout and use the update interface instead of the patch interface of Kubernetes client, or use our kubectl-kruise tools.
$ kubectl-kruise rollout approve rollout/<your-rollout-name> -n <your-rollout-namespace>

How to know current step is Ready?​

All status information about current step is recorded in status.canaryStatus field of Rollout:

  • if status.canaryStatus.CurrentStepIndex does not equal to your expected step index, the current step is NOT ready.
  • if status.canaryStatus.CurrentStepState does not equal to "StepReady" or "Complete", the current step is NOT ready.
func IsRolloutCurrentStepReady(rollout *rolloutsv1beta1.Rollout, stepIndex int32) bool {
    if rollout.Status.CanaryStatus != nil {
        if rollout.Status.CanaryStatus.CurrentStepIndex != stepIndex {
            return false
        }
        switch rollout.Status.CanaryStatus.CurrentSetpState {
        case "StepReady", "Complete":
            return true
        }
    }
    return false
}

But in some automatic scenes(e.g. PaaS platform), before judging whether current step is ready, we should know whether the canaryStatus is corresponding to the current rollout processes (Maybe it corresponds to the last rollout process). We can use rollout-id mechanism to solve this problem.

func IsRolloutCurrentStepReady(workload appsv1.Deployment, rollout *rolloutsv1beta1.Rollout, stepIndex int32) bool {
    if rollout.Status.CanaryStatus != nil {
        rolloutId := workload.Labels["rollouts.kruise.io/rollout-id"]
        if rolloutId != rollout.Status.CanaryStatus.ObservedRolloutID {
            return false
        }
        if rollout.Status.CanaryStatus.CurrentStepIndex != stepIndex {
            return false
        }
        switch rollout.Status.CanaryStatus.CurrentSetpState {
        case "StepReady", "Complete":
            return true
        }
    }
    return false
}

How to do rollback?​

In fact, Kruise Rollout DOES NOT provide the ability to rollback directly. Kruise Rollout prefers that users can rollback workload spec directly to rollback their application. When users need to rollback from “version-2” to ”version-1“, Kruise Rollout will use the native rolling upgrade strategy to quickly rollback, instead of following the multi-batch checkpoint strategy.

1. Apply your old version yaml to kubernetes​

If an anomaly is detected in the new version during the Rollout process, you can roll back to the previous version using the Deployment configuration. For example, deploy the deployment manifest of previous version using the command kubectl apply -f depolyment.yaml without making any changes to the Rollout resource.

2. Gitops sync old revision​

You can roll back by syncing the application's revision to the old version's commit. Execute the following command to synchronize the application to the old version, where revision is the tag of the old version.

argocd app sync rollouts-demo --revision gitops-demo-version-stable

expected output:

Project: default
Server: https://192.168.XX.XX:6443
Namespace: default
URL: https://127.0.0.1:49922/applications/rollouts-demo
Repo: https://github.com/Kuromesi/samples.git
Target: 616b4b6
Path: gitops-demo
SyncWindow: Sync Allowed
Sync Policy: <none>
Sync Status: Synced to 616b4b6
Health Status: Progressing

Operation: Sync
Sync Revision: 616b4b6e010ba4d71a92c0e7d050162956b169b7
Phase: Succeeded
Start: 2023-08-07 16:52:53 +0800 CST
Finished: 2023-08-07 16:52:54 +0800 CST
Duration: 1s
Message: successfully synced (all tasks run)

GROUP KIND NAMESPACE NAME STATUS HEALTH HOOK MESSAGE
 Service default echo-server Synced Healthy service/echo-server unchanged
apps Deployment default echo-server Synced Suspended deployment.apps/echo-server configured
networking.k8s.io Ingress default ingress-demo Synced Progressing ingress.networking.k8s.io/ingress-demo unchanged
rollouts.kruise.io Rollout default rollouts-demo Synced rollout.rollouts.kruise.io/rollouts-demo unchanged

3. Use kruise-tools​

kruise-tools is kubectl plugin for OpenKruise, which provides commandline tools for kruise features, such as kubectl-kruise, which is a standard plugin of kubectl. You can use the command kubectl kruise rollout undo rollout/rollout-demo to roll back a workload, either during the rollout process or after the rollout has finished.

Other Statements​

  • Continuous Release: Assume that Rollout is progressing from "version-1" to "version-2"(uncompleted). Now, workload is modified to "version-3", Rollout will start to progress from beginning step (1-st step).
  • HPA compatible: Assume that you config HPA to your workload and use multi-batch update strategy, we suggest to use "Percent" to specify "steps[x].replicas". If replicas is scaled up/down during rollout progressing, the old and new version replicas will be scaled according the "Percent" configuration.
Last updated on by myname4423