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Application Version Control

Introduction

overall-arch

In KubeVela, ApplicationRevision keeps the snapshot of the application and all its runtime dependencies such as ComponentDefinition, external Policy or referred objects. This revision can be used to review the application changes and rollback to past configurations.

In KubeVela v1.3, for application which uses the PublishVersion feature, we support viewing the history revisions, checking the differences across revisions, rolling back to the latest succeeded revision and re-publishing past revisions.

For application with the app.oam.dev/publishVersion annotation, the workflow runs are strictly controlled. The annotation, which is noted as publishVersion in the following paragraphs, is used to identify a static version of the application and its dependencies.

When the annotation is updated to a new value, the application will generate a new revision no matter if the application spec or the dependencies are changed. It will then trigger a fresh new run of workflow after terminating the previous run.

During the running of workflow, all related data are retrieved from the ApplicationRevision, which means the changes to the application spec or the dependencies will not take effects until a newer publishVerison is annotated.

Use Guide

Fo example, let's start with an application with external workflow and policies to deploy podinfo in managed clusters.

For external workflow and policies, please refer to Multi-cluster Application Delivery for more details.

apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
name: podinfo
namespace: examples
annotations:
app.oam.dev/publishVersion: alpha1
spec:
components:
- name: podinfo
type: webservice
properties:
image: stefanprodan/podinfo:6.0.1
workflow:
ref: make-release-in-hangzhou
---
apiVersion: core.oam.dev/v1alpha1
kind: Policy
metadata:
name: override-high-availability
namespace: examples
type: override
properties:
components:
- type: webservice
traits:
- type: scaler
properties:
replicas: 3
---
apiVersion: core.oam.dev/v1alpha1
kind: Policy
metadata:
name: topology-hangzhou-clusters
namespace: examples
type: topology
properties:
clusterLabelSelector:
region: hangzhou
---
apiVersion: core.oam.dev/v1alpha1
kind: Workflow
metadata:
name: make-release-in-hangzhou
namespace: examples
steps:
- name: deploy-hangzhou
type: deploy
properties:
policies: ["topology-hangzhou-clusters", "override-high-availability"]

You can check the application status by running vela status podinfo -n examples and view all the related real-time resources by vela status podinfo -n examples --tree --detail.

$ vela status podinfo -n examples
vela status podinfo -n examples
About:

Name: podinfo
Namespace: examples
Created at: 2022-04-13 19:32:02 +0800 CST
Status: runningWorkflow

Workflow:

mode: DAG
finished: false
Suspend: false
Terminated: false
Steps
- id:auqaxnbix2
name:deploy-hangzhou
type:deploy
phase:running
message:wait healthy

Services:

- Name: podinfo
Cluster: velad-003 Namespace: examples
Type: webservice
Unhealthy Ready:0/3
Traits:
✅ scaler
- Name: podinfo
Cluster: velad-002 Namespace: examples
Type: webservice
Unhealthy Ready:0/3
Traits:
✅ scaler

$ vela status podinfo -n examples --tree --detail
CLUSTER NAMESPACE RESOURCE STATUS APPLY_TIME DETAIL
hangzhou1 ─── examples ─── Deployment/podinfo updated 2022-04-13 19:32:03 Ready: 3/3 Up-to-date: 3 Available: 3 Age: 4m16s
hangzhou2 ─── examples ─── Deployment/podinfo updated 2022-04-13 19:32:03 Ready: 3/3 Up-to-date: 3 Available: 3 Age: 4m16s

This application should be successful after a while. Now if we edit the component image and set it to an invalid value, such as stefanprodan/podinfo:6.0.xxx. The application will not re-run the workflow to make this change take effect automatically. But the application spec changes, it means the next workflow run will update the deployment image.

Inspect Changes across Revisions

Now let's run vela live-diff podinfo -n examples to check this diff

$ vela live-diff podinfo -n examples
* Application (podinfo) has been modified(*)
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
annotations:
app.oam.dev/publishVersion: alpha1
name: podinfo
namespace: examples
spec:
components:
- name: podinfo
properties:
- image: stefanprodan/podinfo:6.0.1
+ image: stefanprodan/podinfo:6.0.xxx
type: webservice
workflow:
ref: make-release-in-hangzhou
status: {}

* External Policy (topology-hangzhou-clusters) has no change
* External Policy (override-high-availability) has no change
* External Workflow (make-release-in-hangzhou) has no change

We can see all the changes of the application spec and the dependencies. Now let's make this change take effects. There are two ways to make it take effects. You can choose any one of them.

  1. Update the publishVersion annotation in the application to alpha2 to trigger the re-run of workflow.
  2. Run vela up podinfo -n examples --publish-version alpha2 to publish the new version.

We will find the application stuck at runningWorkflow as the deployment cannot finish the update progress due to the invalid image.

Now we can run vela revision list podinfo -n examples to list all the available revisions.

$ vela revision list podinfo -n examples
NAME PUBLISH_VERSION SUCCEEDED HASH BEGIN_TIME STATUS SIZE
podinfo-v1 alpha1 true 65844934c2d07288 2022-04-13 19:32:02 Succeeded 23.7 KiB
podinfo-v2 alpha2 false 44124fb1a5146a4d 2022-04-13 19:46:50 Executing 23.7 KiB

Rollback to Last Successful Revision

Before rolling back, we need to suspend the workflow of the application first. Run vela workflow suspend podinfo -n examples. After the application workflow is suspended, run vela workflow rollback podinfo -n examples, the workflow will be rolled back and the application resources will restore to the succeeded state.

$ vela workflow suspend podinfo -n examples
Successfully suspend workflow: podinfo
$ vela workflow rollback podinfo -n examples
Find succeeded application revision podinfo-v1 (PublishVersion: alpha1) to rollback.
Application spec rollback successfully.
Application status rollback successfully.
Application rollback completed.
Application outdated revision cleaned up.

Now if we return back to see all the resources, we will find the resources have been turned back to use the valid image again.

$ vela status podinfo -n examples --tree --detail --detail-format wide
CLUSTER NAMESPACE RESOURCE STATUS APPLY_TIME DETAIL
hangzhou1 ─── examples ─── Deployment/podinfo updated 2022-04-13 19:32:03 Ready: 3/3 Up-to-date: 3 Available: 3 Age: 17m Containers: podinfo Images: stefanprodan/podinfo:6.0.1 Selector: app.oam.dev/component=podinfo
hangzhou2 ─── examples ─── Deployment/podinfo updated 2022-04-13 19:32:03 Ready: 3/3 Up-to-date: 3 Available: 3 Age: 17m Containers: podinfo Images: stefanprodan/podinfo:6.0.1 Selector: app.oam.dev/component=podinfo

Re-publish a History Revision

This feature is introduced after v1.3.1.

Rolling back revision allows you to directly go back to the latest successful state. An alternative way is to re-publish an old revision, which will re-run the workflow but can go back to any revision that is still available.

For example, you might have 2 successful revisions available to use.

$ vela revision list podinfo -n examples
NAME PUBLISH_VERSION SUCCEEDED HASH BEGIN_TIME STATUS SIZE
podinfo-v1 alpha1 true 65844934c2d07288 2022-04-13 20:45:19 Succeeded 23.7 KiB
podinfo-v2 alpha2 true 4acae1a66013283 2022-04-13 20:45:45 Succeeded 23.7 KiB
podinfo-v3 alpha3 false 44124fb1a5146a4d 2022-04-13 20:46:28 Executing 23.7 KiB

Alternatively, you can directly use vela up podinfo -n examples --revision podinfo-v1 --publish-version beta1 to re-publish the earliest version. This process will let the application to use the past revision and re-run the whole workflow. A new revision that is totally same with the specified one will be generated.

NAME            PUBLISH_VERSION SUCCEEDED       HASH                    BEGIN_TIME              STATUS          SIZE
podinfo-v1 alpha1 true 65844934c2d07288 2022-04-13 20:45:19 Succeeded 23.7 KiB
podinfo-v2 alpha2 true 4acae1a66013283 2022-04-13 20:45:45 Succeeded 23.7 KiB
podinfo-v3 alpha3 false 44124fb1a5146a4d 2022-04-13 20:46:28 Failed 23.7 KiB
podinfo-v4 beta1 true 65844934c2d07288 2022-04-13 20:46:49 Succeeded 23.7 KiB

You can find that the beta1 version shares the same hash with alpha1 version.

By default, application will hold at most 10 revisions. If you want to modify this number, you can set it in the --application-revision-limit bootstrap parameter of KubeVela controller.