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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:

# app.yaml
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
name: vela-app
spec:
components:
- name: express-server
type: webservice
properties:
image: crccheck/hello-world
port: 8000
traits:
- type: ingress
properties:
domain: testsvc.example.com
http:
"/": 8000
kubectl vela dry-run -f app.yaml
---
# Application(vela-app) -- Comopnent(express-server)
---
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app.oam.dev/appRevision: ""
app.oam.dev/component: express-server
app.oam.dev/name: vela-app
workload.oam.dev/type: webservice
spec:
selector:
matchLabels:
app.oam.dev/component: express-server
template:
metadata:
labels:
app.oam.dev/component: express-server
spec:
containers:
- image: crccheck/hello-world
name: express-server
ports:
- containerPort: 8000
---
apiVersion: v1
kind: Service
metadata:
labels:
app.oam.dev/appRevision: ""
app.oam.dev/component: express-server
app.oam.dev/name: vela-app
trait.oam.dev/resource: service
trait.oam.dev/type: ingress
name: express-server
spec:
ports:
- port: 8000
targetPort: 8000
selector:
app.oam.dev/component: express-server
---
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
labels:
app.oam.dev/appRevision: ""
app.oam.dev/component: express-server
app.oam.dev/name: vela-app
trait.oam.dev/resource: ingress
trait.oam.dev/type: ingress
name: express-server
spec:
rules:
- host: testsvc.example.com
http:
paths:
- backend:
serviceName: express-server
servicePort: 8000
path: /
---

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.

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

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

# new-app.yaml
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
name: vela-app
spec:
components:
- name: express-server
type: webservice
properties:
image: crccheck/hello-world
port: 8080 # change port
cpu: 0.5 # add requests cpu units
- name: my-task # add a component
type: task
properties:
image: busybox
cmd: ["sleep", "1000"]
traits:
- type: ingress
properties:
domain: testsvc.example.com
http:
"/": 8080 # change port

Run live-diff like this:

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
---
# Application (vela-app) has been modified(*)
---
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
creationTimestamp: null
name: vela-app
namespace: default
spec:
components:
- name: express-server
properties:
+ cpu: 0.5
image: crccheck/hello-world
- port: 8000
+ port: 8080
+ type: webservice
+ - name: my-task
+ properties:
+ cmd:
+ - sleep
+ - "1000"
+ image: busybox
traits:
- properties:
domain: testsvc.example.com
http:
- /: 8000
+ /: 8080
type: ingress
- type: webservice
+ type: task
status:
batchRollingState: ""
currentBatch: 0
rollingState: ""
upgradedReadyReplicas: 0
upgradedReplicas: 0
---
## Component (express-server) has been modified(*)
---
apiVersion: core.oam.dev/v1alpha2
kind: Component
metadata:
creationTimestamp: null
labels:
app.oam.dev/name: vela-app
name: express-server
spec:
workload:
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app.oam.dev/appRevision: ""
app.oam.dev/component: express-server
app.oam.dev/name: vela-app
workload.oam.dev/type: webservice
spec:
selector:
matchLabels:
app.oam.dev/component: express-server
template:
metadata:
labels:
app.oam.dev/component: express-server
spec:
containers:
- image: crccheck/hello-world
name: express-server
ports:
- - containerPort: 8000
+ - containerPort: 8080
status:
observedGeneration: 0
---
### Component (express-server) / Trait (ingress/service) has been removed(-)
---
- apiVersion: v1
- kind: Service
- metadata:
- labels:
- app.oam.dev/appRevision: ""
- app.oam.dev/component: express-server
- app.oam.dev/name: vela-app
- trait.oam.dev/resource: service
- trait.oam.dev/type: ingress
- name: express-server
- spec:
- ports:
- - port: 8000
- targetPort: 8000
- selector:
- app.oam.dev/component: express-server
---
### Component (express-server) / Trait (ingress/ingress) has been removed(-)
---
- apiVersion: networking.k8s.io/v1beta1
- kind: Ingress
- metadata:
- labels:
- app.oam.dev/appRevision: ""
- app.oam.dev/component: express-server
- app.oam.dev/name: vela-app
- trait.oam.dev/resource: ingress
- trait.oam.dev/type: ingress
- name: express-server
- spec:
- rules:
- - host: testsvc.example.com
- http:
- paths:
- - backend:
- serviceName: express-server
- servicePort: 8000
- path: /
---
## Component (my-task) has been added(+)
---
+ apiVersion: core.oam.dev/v1alpha2
+ kind: Component
+ metadata:
+ creationTimestamp: null
+ labels:
+ app.oam.dev/name: vela-app
+ name: my-task
+ spec:
+ workload:
+ apiVersion: batch/v1
+ kind: Job
+ metadata:
+ labels:
+ app.oam.dev/appRevision: ""
+ app.oam.dev/component: my-task
+ app.oam.dev/name: vela-app
+ workload.oam.dev/type: task
+ spec:
+ completions: 1
+ parallelism: 1
+ template:
+ spec:
+ containers:
+ - command:
+ - sleep
+ - "1000"
+ image: busybox
+ name: my-task
+ restartPolicy: Never
+ status:
+ observedGeneration: 0
---
### Component (my-task) / Trait (ingress/service) has been added(+)
---
+ apiVersion: v1
+ kind: Service
+ metadata:
+ labels:
+ app.oam.dev/appRevision: ""
+ app.oam.dev/component: my-task
+ app.oam.dev/name: vela-app
+ trait.oam.dev/resource: service
+ trait.oam.dev/type: ingress
+ name: my-task
+ spec:
+ ports:
+ - port: 8080
+ targetPort: 8080
+ selector:
+ app.oam.dev/component: my-task
---
### Component (my-task) / Trait (ingress/ingress) has been added(+)
---
+ apiVersion: networking.k8s.io/v1beta1
+ kind: Ingress
+ metadata:
+ labels:
+ app.oam.dev/appRevision: ""
+ app.oam.dev/component: my-task
+ app.oam.dev/name: vela-app
+ trait.oam.dev/resource: ingress
+ trait.oam.dev/type: ingress
+ name: my-task
+ spec:
+ rules:
+ - host: testsvc.example.com
+ http:
+ paths:
+ - backend:
+ serviceName: my-task
+ servicePort: 8080
+ path: /
Last updated on by yangsoon