Version: v1.0

Dry-Run and Live-Diff

KubeVela allows you to dry-run and live-diff your application.

Dry-Run the Application

Dry run will help you to understand what are the real resources which will to be expanded and deployed to the Kubernetes cluster. In other words, it will mock to run the same logic as KubeVela’s controller and output the results locally.

For example, let’s dry-run the following application:

  1. # app.yaml
  2. apiVersion: core.oam.dev/v1beta1
  3. kind: Application
  4. metadata:
  5.   name: vela-app
  6. spec:
  7.   components:
  8.     - name: express-server
  9.       type: webservice
  10.       properties:
  11.         image: crccheck/hello-world
  12.         port: 8000
  13.       traits:
  14.         - type: ingress
  15.           properties:
  16.             domain: testsvc.example.com
  17.             http:
  18.               "/": 8000
  1. kubectl vela dry-run -f app.yaml
  2. ---
  3. # Application(vela-app) -- Comopnent(express-server)
  4. ---
  7. apiVersion: apps/v1
  8. kind: Deployment
  9. metadata:
  10.   labels:
  11.     app.oam.dev/appRevision: ""
  12.     app.oam.dev/component: express-server
  13.     app.oam.dev/name: vela-app
  14.     workload.oam.dev/type: webservice
  15. spec:
  16.   selector:
  17.     matchLabels:
  18.       app.oam.dev/component: express-server
  19.   template:
  20.     metadata:
  21.       labels:
  22.         app.oam.dev/component: express-server
  23.     spec:
  24.       containers:
  25.       - image: crccheck/hello-world
  26.         name: express-server
  27.         ports:
  28.         - containerPort: 8000
  31. ---
  32. apiVersion: v1
  33. kind: Service
  34. metadata:
  35.   labels:
  36.     app.oam.dev/appRevision: ""
  37.     app.oam.dev/component: express-server
  38.     app.oam.dev/name: vela-app
  39.     trait.oam.dev/resource: service
  40.     trait.oam.dev/type: ingress
  41.   name: express-server
  42. spec:
  43.   ports:
  44.   - port: 8000
  45.     targetPort: 8000
  46.   selector:
  47.     app.oam.dev/component: express-server
  50. ---
  51. apiVersion: networking.k8s.io/v1beta1
  52. kind: Ingress
  53. metadata:
  54.   labels:
  55.     app.oam.dev/appRevision: ""
  56.     app.oam.dev/component: express-server
  57.     app.oam.dev/name: vela-app
  58.     trait.oam.dev/resource: ingress
  59.     trait.oam.dev/type: ingress
  60.   name: express-server
  61. spec:
  62.   rules:
  63.   - host: testsvc.example.com
  64.     http:
  65.       paths:
  66.       - backend:
  67.           serviceName: express-server
  68.           servicePort: 8000
  69.         path: /
  72. ---

In this example, the definitions(webservice and ingress) which vela-app depends on is the built-in components and traits of KubeVela. You can also use -d or --definitions to specify your local definition files.

-d or --definitions permitting user to provide capability definitions used in the application from local files. dry-run cmd will prioritize the provided capabilities than the living ones in the cluster.

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 you have just deployed the application in dry-run section. Then you can list the revisions of the Application.

  1. $ kubectl get apprev -l app.oam.dev/name=vela-app
  2. NAME          AGE
  3. vela-app-v1   50s

Assume we’re going to upgrade the application like below.

  1. # new-app.yaml
  2. apiVersion: core.oam.dev/v1beta1
  3. kind: Application
  4. metadata:
  5.   name: vela-app
  6. spec:
  7.   components:
  8.     - name: express-server
  9.       type: webservice
  10.       properties:
  11.         image: crccheck/hello-world
  12.         port: 8080 # change port
  13.         cpu: 0.5 # add requests cpu units
  14.     - name: my-task # add a component
  15.       type: task
  16.       properties:
  17.         image: busybox
  18.         cmd: ["sleep", "1000"]
  19.       traits:
  20.         - type: ingress
  21.           properties:
  22.             domain: testsvc.example.com
  23.             http:
  24.               "/": 8080 # change port

Run live-diff like this:

  1. kubectl vela live-diff -f new-app.yaml -r vela-app-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

  1. ---
  2. # Application (vela-app) has been modified(*)
  3. ---
  4.   apiVersion: core.oam.dev/v1beta1
  5.   kind: Application
  6.   metadata:
  7.     creationTimestamp: null
  8.     name: vela-app
  9.     namespace: default
  10.   spec:
  11.     components:
  12.     - name: express-server
  13.       properties:
  14. +       cpu: 0.5
  15.         image: crccheck/hello-world
  16. -       port: 8000
  17. +       port: 8080
  18. +     type: webservice
  19. +   - name: my-task
  20. +     properties:
  21. +       cmd:
  22. +       - sleep
  23. +       - "1000"
  24. +       image: busybox
  25.       traits:
  26.       - properties:
  27.           domain: testsvc.example.com
  28.           http:
  29. -           /: 8000
  30. +           /: 8080
  31.         type: ingress
  32. -     type: webservice
  33. +     type: task
  34.   status:
  35.     batchRollingState: ""
  36.     currentBatch: 0
  37.     rollingState: ""
  38.     upgradedReadyReplicas: 0
  39.     upgradedReplicas: 0
  42. ---
  43. ## Component (express-server) has been modified(*)
  44. ---
  45.   apiVersion: core.oam.dev/v1alpha2
  46.   kind: Component
  47.   metadata:
  48.     creationTimestamp: null
  49.     labels:
  50.       app.oam.dev/name: vela-app
  51.     name: express-server
  52.   spec:
  53.     workload:
  54.       apiVersion: apps/v1
  55.       kind: Deployment
  56.       metadata:
  57.         labels:
  58.           app.oam.dev/appRevision: ""
  59.           app.oam.dev/component: express-server
  60.           app.oam.dev/name: vela-app
  61.           workload.oam.dev/type: webservice
  62.       spec:
  63.         selector:
  64.           matchLabels:
  65.             app.oam.dev/component: express-server
  66.         template:
  67.           metadata:
  68.             labels:
  69.               app.oam.dev/component: express-server
  70.           spec:
  71.             containers:
  72.             - image: crccheck/hello-world
  73.               name: express-server
  74.               ports:
  75. -             - containerPort: 8000
  76. +             - containerPort: 8080
  77.   status:
  78.     observedGeneration: 0
  81. ---
  82. ### Component (express-server) / Trait (ingress/service) has been removed(-)
  83. ---
  84. - apiVersion: v1
  85. - kind: Service
  86. - metadata:
  87. -   labels:
  88. -     app.oam.dev/appRevision: ""
  89. -     app.oam.dev/component: express-server
  90. -     app.oam.dev/name: vela-app
  91. -     trait.oam.dev/resource: service
  92. -     trait.oam.dev/type: ingress
  93. -   name: express-server
  94. - spec:
  95. -   ports:
  96. -   - port: 8000
  97. -     targetPort: 8000
  98. -   selector:
  99. -     app.oam.dev/component: express-server
  102. ---
  103. ### Component (express-server) / Trait (ingress/ingress) has been removed(-)
  104. ---
  105. - apiVersion: networking.k8s.io/v1beta1
  106. - kind: Ingress
  107. - metadata:
  108. -   labels:
  109. -     app.oam.dev/appRevision: ""
  110. -     app.oam.dev/component: express-server
  111. -     app.oam.dev/name: vela-app
  112. -     trait.oam.dev/resource: ingress
  113. -     trait.oam.dev/type: ingress
  114. -   name: express-server
  115. - spec:
  116. -   rules:
  117. -   - host: testsvc.example.com
  118. -     http:
  119. -       paths:
  120. -       - backend:
  121. -           serviceName: express-server
  122. -           servicePort: 8000
  123. -         path: /
  126. ---
  127. ## Component (my-task) has been added(+)
  128. ---
  129. + apiVersion: core.oam.dev/v1alpha2
  130. + kind: Component
  131. + metadata:
  132. +   creationTimestamp: null
  133. +   labels:
  134. +     app.oam.dev/name: vela-app
  135. +   name: my-task
  136. + spec:
  137. +   workload:
  138. +     apiVersion: batch/v1
  139. +     kind: Job
  140. +     metadata:
  141. +       labels:
  142. +         app.oam.dev/appRevision: ""
  143. +         app.oam.dev/component: my-task
  144. +         app.oam.dev/name: vela-app
  145. +         workload.oam.dev/type: task
  146. +     spec:
  147. +       completions: 1
  148. +       parallelism: 1
  149. +       template:
  150. +         spec:
  151. +           containers:
  152. +           - command:
  153. +             - sleep
  154. +             - "1000"
  155. +             image: busybox
  156. +             name: my-task
  157. +           restartPolicy: Never
  158. + status:
  159. +   observedGeneration: 0
  162. ---
  163. ### Component (my-task) / Trait (ingress/service) has been added(+)
  164. ---
  165. + apiVersion: v1
  166. + kind: Service
  167. + metadata:
  168. +   labels:
  169. +     app.oam.dev/appRevision: ""
  170. +     app.oam.dev/component: my-task
  171. +     app.oam.dev/name: vela-app
  172. +     trait.oam.dev/resource: service
  173. +     trait.oam.dev/type: ingress
  174. +   name: my-task
  175. + spec:
  176. +   ports:
  177. +   - port: 8080
  178. +     targetPort: 8080
  179. +   selector:
  180. +     app.oam.dev/component: my-task
  183. ---
  184. ### Component (my-task) / Trait (ingress/ingress) has been added(+)
  185. ---
  186. + apiVersion: networking.k8s.io/v1beta1
  187. + kind: Ingress
  188. + metadata:
  189. +   labels:
  190. +     app.oam.dev/appRevision: ""
  191. +     app.oam.dev/component: my-task
  192. +     app.oam.dev/name: vela-app
  193. +     trait.oam.dev/resource: ingress
  194. +     trait.oam.dev/type: ingress
  195. +   name: my-task
  196. + spec:
  197. +   rules:
  198. +   - host: testsvc.example.com
  199. +     http:
  200. +       paths:
  201. +       - backend:
  202. +           serviceName: my-task
  203. +           servicePort: 8080
  204. +         path: /