--- title: Version Control --- ## Component Revision You can specify a generated component instance revision with field `spec.components[*].externalRevision` in Application like below: ```yaml apiVersion: core.oam.dev/v1beta1 kind: Application metadata: name: myapp spec: components: - name: express-server type: webservice externalRevision: express-server-v1 properties: image: stefanprodan/podinfo:4.0.3 ``` If the field is not specified, it will generated by the name rule `-`. After the Application created, it will generate a ControllerRevision object for each component. * Get the revision for component instance ```shell $ kubectl get controllerrevision -l controller.oam.dev/component=express-server NAME CONTROLLER REVISION AGE express-server-v1 application.core.oam.dev/myapp 1 2m40s express-server-v2 application.core.oam.dev/myapp 2 2m12s ``` You can specify the component revision for [component rolling update](./traits/rollout). ## Specify Component/Trait Capability Revision in Application When the capabilities(Component or Trait) changes, KubeVela will generate a definition revision automatically. * Check ComponentDefinition Revision ```shell $ kubectl get definitionrevision -l="componentdefinition.oam.dev/name=webservice" -n vela-system NAME REVISION HASH TYPE webservice-v1 1 3f6886d9832021ba Component webservice-v2 2 b3b9978e7164d973 Component ``` * Check TraitDefinition Revision ```shell $ kubectl get definitionrevision -l="trait.oam.dev/name=rollout" -n vela-system NAME REVISION HASH TYPE rollout-v1 1 e441f026c1884b14 Trait ``` You can specify the revision with `@version` approach, for example, if a user want to stick to using the `v1` revision of `webservice` component: ```yaml apiVersion: core.oam.dev/v1beta1 kind: Application metadata: name: myapp spec: components: - name: express-server type: webservice@v1 properties: image: stefanprodan/podinfo:4.0.3 ``` In this way, if system admin changes the ComponentDefinition, it won't affect your application. If no revision specified, KubeVela will use the latest revision when you upgrade your application. ## Application Revision When updating an application entity except workflow, KubeVela will create a new revision as a snapshot for this change. ```shell $ kubectl get apprev -l app.oam.dev/name=myapp NAME AGE myapp-v1 54m myapp-v2 53m myapp-v3 18s ``` You can get all the information related with the application in the application revision, including the application spec, and all related definitions. ```yaml apiVersion: core.oam.dev/v1beta1 kind: ApplicationRevision metadata: labels: app.oam.dev/app-revision-hash: a74b4a514ba2fc08 app.oam.dev/name: myapp name: myapp-v3 namespace: default ... spec: application: apiVersion: core.oam.dev/v1beta1 kind: Application metadata: name: myapp namespace: default ... spec: components: - name: express-server properties: image: stefanprodan/podinfo:5.0.3 type: webservice@v1 ... componentDefinitions: webservice: apiVersion: core.oam.dev/v1beta1 kind: ComponentDefinition metadata: name: webservice namespace: vela-system ... spec: schematic: cue: ... traitDefinitions: ... ``` ## Live-Diff the `Application` Live-diff helps you to have a preview of what would change if you're going to upgrade an application without making any changes to the living cluster. This feature is extremely useful for serious production deployment, and make the upgrade under control It basically generates a diff between the specific revision of running instance and the local candidate application. The result shows the changes (added/modified/removed/no_change) of the application as well as its sub-resources, such as components and traits. Assume we're going to upgrade the application like below. ```yaml # new-app.yaml apiVersion: core.oam.dev/v1beta1 kind: Application metadata: name: myapp spec: components: - name: express-server type: webservice@v1 properties: image: crccheck/hello-world # change the image ``` Run live-diff like this: ```shell vela live-diff -f new-app.yaml -r myapp-v1 ``` `-r` or `--revision` is a flag that specifies the name of a living ApplicationRevision with which you want to compare the updated application. `-c` or `--context` is a flag that specifies the number of lines shown around a change. The unchanged lines which are out of the context of a change will be omitted. It's useful if the diff result contains a lot of unchanged content while you just want to focus on the changed ones.
Click to view the details of diff result ```bash --- # Application (myapp) has been modified(*) --- apiVersion: core.oam.dev/v1beta1 kind: Application metadata: - annotations: - kubectl.kubernetes.io/last-applied-configuration: | - {"apiVersion":"core.oam.dev/v1beta1","kind":"Application","metadata":{"annotations":{},"name":"myapp","namespace":"default"},"spec":{"components":[{"externalRevision":"express-server-v1","name":"express-server","properties":{"image":"stefanprodan/podinfo:4.0.3"},"type":"webservice"}]}} creationTimestamp: null - finalizers: - - app.oam.dev/resource-tracker-finalizer name: myapp namespace: default spec: components: - - externalRevision: express-server-v1 - name: express-server + - name: express-server properties: - image: stefanprodan/podinfo:4.0.3 - type: webservice + image: crccheck/hello-world + type: webservice@v1 status: rollout: batchRollingState: "" currentBatch: 0 lastTargetAppRevision: "" rollingState: "" upgradedReadyReplicas: 0 upgradedReplicas: 0 --- ## Component (express-server) has been modified(*) --- apiVersion: apps/v1 kind: Deployment metadata: - annotations: - kubectl.kubernetes.io/last-applied-configuration: | - {"apiVersion":"core.oam.dev/v1beta1","kind":"Application","metadata":{"annotations":{},"name":"myapp","namespace":"default"},"spec":{"components":[{"externalRevision":"express-server-v1","name":"express-server","properties":{"image":"stefanprodan/podinfo:4.0.3"},"type":"webservice"}]}} + annotations: {} labels: app.oam.dev/appRevision: "" app.oam.dev/component: express-server app.oam.dev/name: myapp app.oam.dev/resourceType: WORKLOAD - workload.oam.dev/type: webservice + workload.oam.dev/type: webservice-v1 name: express-server namespace: default spec: selector: matchLabels: app.oam.dev/component: express-server template: metadata: labels: app.oam.dev/component: express-server app.oam.dev/revision: KUBEVELA_COMPONENT_REVISION_PLACEHOLDER spec: containers: - - image: stefanprodan/podinfo:4.0.3 + - image: crccheck/hello-world name: express-server ports: - containerPort: 80 ```
Furthermore, you can integrate the revision for application snapshot and recovery with your own system.