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Version: v1.0

Debug, Test and Dry-run

With flexibility in defining abstractions, it's important to be able to debug, test and dry-run the CUE based definitions. This tutorial will show this step by step.

Prerequisites#

Please make sure below CLIs are present in your environment:

Define Definition and Template#

We recommend to define the Definition Object in two separate parts: the CRD part and the CUE template. This enable us to debug, test and dry-run the CUE template.

Let's name the CRD part as def.yaml.

apiVersion: core.oam.dev/v1beta1
kind: ComponentDefinition
metadata:
name: microservice
annotations:
definition.oam.dev/description: "Describes a microservice combo Deployment with Service."
spec:
workload:
definition:
apiVersion: apps/v1
kind: Deployment
schematic:
cue:
template: |

And the CUE template part as def.cue, then we can use CUE commands such as cue fmt / cue vet to format and validate the CUE file.

output: {
// Deployment
apiVersion: "apps/v1"
kind: "Deployment"
metadata: {
name: context.name
namespace: "default"
}
spec: {
selector: matchLabels: {
"app": context.name
}
template: {
metadata: {
labels: {
"app": context.name
"version": parameter.version
}
}
spec: {
serviceAccountName: "default"
terminationGracePeriodSeconds: parameter.podShutdownGraceSeconds
containers: [{
name: context.name
image: parameter.image
ports: [{
if parameter.containerPort != _|_ {
containerPort: parameter.containerPort
}
if parameter.containerPort == _|_ {
containerPort: parameter.servicePort
}
}]
if parameter.env != _|_ {
env: [
for k, v in parameter.env {
name: k
value: v
},
]
}
resources: {
requests: {
if parameter.cpu != _|_ {
cpu: parameter.cpu
}
if parameter.memory != _|_ {
memory: parameter.memory
}
}
}
}]
}
}
}
}
// Service
outputs: service: {
apiVersion: "v1"
kind: "Service"
metadata: {
name: context.name
labels: {
"app": context.name
}
}
spec: {
type: "ClusterIP"
selector: {
"app": context.name
}
ports: [{
port: parameter.servicePort
if parameter.containerPort != _|_ {
targetPort: parameter.containerPort
}
if parameter.containerPort == _|_ {
targetPort: parameter.servicePort
}
}]
}
}
parameter: {
version: *"v1" | string
image: string
servicePort: int
containerPort?: int
// +usage=Optional duration in seconds the pod needs to terminate gracefully
podShutdownGraceSeconds: *30 | int
env: [string]: string
cpu?: string
memory?: string
}

After everything is done, there's a script hack/vela-templates/mergedef.sh to merge the def.yaml and def.cue into a completed Definition Object.

$ ./hack/vela-templates/mergedef.sh def.yaml def.cue > microservice-def.yaml

Debug CUE template#

Use cue vet to Validate#

$ cue vet def.cue
output.metadata.name: reference "context" not found:
./def.cue:6:14
output.spec.selector.matchLabels.app: reference "context" not found:
./def.cue:11:11
output.spec.template.metadata.labels.app: reference "context" not found:
./def.cue:16:17
output.spec.template.spec.containers.name: reference "context" not found:
./def.cue:24:13
outputs.service.metadata.name: reference "context" not found:
./def.cue:62:9
outputs.service.metadata.labels.app: reference "context" not found:
./def.cue:64:11
outputs.service.spec.selector.app: reference "context" not found:
./def.cue:70:11

The reference "context" not found is a common error in this step as context is a runtime information that only exist in KubeVela controllers. In order to validate the CUE template end-to-end, we can add a mock context in def.cue.

Note that you need to remove all mock data when you finished the validation.

... // existing template data
context: {
name: string
}

Then execute the command:

$ cue vet def.cue
some instances are incomplete; use the -c flag to show errors or suppress this message

The reference "context" not found error is gone, but cue vet only validates the data type which is not enough to ensure the login in template is correct. Hence we need to use cue vet -c for complete validation:

$ cue vet def.cue -c
context.name: incomplete value string
output.metadata.name: incomplete value string
output.spec.selector.matchLabels.app: incomplete value string
output.spec.template.metadata.labels.app: incomplete value string
output.spec.template.spec.containers.0.image: incomplete value string
output.spec.template.spec.containers.0.name: incomplete value string
output.spec.template.spec.containers.0.ports.0.containerPort: incomplete value int
outputs.service.metadata.labels.app: incomplete value string
outputs.service.metadata.name: incomplete value string
outputs.service.spec.ports.0.port: incomplete value int
outputs.service.spec.ports.0.targetPort: incomplete value int
outputs.service.spec.selector.app: incomplete value string
parameter.image: incomplete value string
parameter.servicePort: incomplete value int

It now complains some runtime data is incomplete (because context and parameter do not have value), let's now fill in more mock data in the def.cue file:

context: {
name: "test-app"
}
parameter: {
version: "v2"
image: "image-address"
servicePort: 80
containerPort: 8000
env: {"PORT": "8000"}
cpu: "500m"
memory: "128Mi"
}

It won't complain now which means validation is passed:

cue vet def.cue -c

Use cue export to Check the Rendered Resources#

The cue export can export rendered result in YAMl foramt:

$ cue export -e output def.cue --out yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: test-app
namespace: default
spec:
selector:
matchLabels:
app: test-app
template:
metadata:
labels:
app: test-app
version: v2
spec:
serviceAccountName: default
terminationGracePeriodSeconds: 30
containers:
- name: test-app
image: image-address
$ cue export -e outputs.service def.cue --out yaml
apiVersion: v1
kind: Service
metadata:
name: test-app
labels:
app: test-app
spec:
selector:
app: test-app
type: ClusterIP

Test CUE Template with Kube package#

KubeVela automatically generates internal CUE packages for all built-in Kubernetes API resources including CRDs. You can import them in CUE template to simplify your templates and help you do the validation.

There are two kinds of ways to import internal kube packages.

  1. Import them with fixed style: kube/<apiVersion> and using it by Kind.
    import (
    apps "kube/apps/v1"
    corev1 "kube/v1"
    )
    // output is validated by Deployment.
    output: apps.#Deployment
    outputs: service: corev1.#Service
    This way is very easy to remember and use because it aligns with the K8s Object usage, only need to add a prefix kube/ before apiVersion. While this way only supported in KubeVela, so you can only debug and test it with vela system dry-run.
  2. Import them with third-party packages style. You can run vela system cue-packages to list all build-in kube packages to know the third-party packages supported currently.
    $ vela system cue-packages
    DEFINITION-NAME IMPORT-PATH USAGE
    #Deployment k8s.io/apps/v1 Kube Object for apps/v1.Deployment
    #Service k8s.io/core/v1 Kube Object for v1.Service
    #Secret k8s.io/core/v1 Kube Object for v1.Secret
    #Node k8s.io/core/v1 Kube Object for v1.Node
    #PersistentVolume k8s.io/core/v1 Kube Object for v1.PersistentVolume
    #Endpoints k8s.io/core/v1 Kube Object for v1.Endpoints
    #Pod k8s.io/core/v1 Kube Object for v1.Pod
    In fact, they are all built-in packages, but you can import them with the import-path like the third-party packages. In this way, you could debug with cue cli client.

A workflow to debug with kube packages#

Here's a workflow that you can debug and test the CUE template with cue CLI and use exactly the same CUE template in KubeVela.

  1. Create a test directory, Init CUE modules.
mkdir cue-debug && cd cue-debug/
cue mod init oam.dev
go mod init oam.dev
touch def.cue
  1. Download the third-party packages by using cue CLI.

In KubeVela, we don't need to download these packages as they're automatically generated from K8s API. But for local test, we need to use cue get go to fetch Go packages and convert them to CUE format files.

So, by using K8s Deployment and Serivice, we need download and convert to CUE definitions for the core and apps Kubernetes modules like below:

cue get go k8s.io/api/core/v1
cue get go k8s.io/api/apps/v1

After that, the module directory will show the following contents:

├── cue.mod
│ ├── gen
│ │ └── k8s.io
│ │ ├── api
│ │ │ ├── apps
│ │ │ └── core
│ │ └── apimachinery
│ │ └── pkg
│ ├── module.cue
│ ├── pkg
│ └── usr
├── def.cue
├── go.mod
└── go.sum

The package import path in CUE template should be:

import (
apps "k8s.io/api/apps/v1"
corev1 "k8s.io/api/core/v1"
)
  1. Refactor directory hierarchy.

Our goal is to test template locally and use the same template in KubeVela. So we need to refactor our local CUE module directories a bit to align with the import path provided by KubeVela,

Copy the apps and core from cue.mod/gen/k8s.io/api to cue.mod/gen/k8s.io. (Note we should keep the source directory apps and core in gen/k8s.io/api to avoid package dependency issues).

cp -r cue.mod/gen/k8s.io/api/apps cue.mod/gen/k8s.io
cp -r cue.mod/gen/k8s.io/api/core cue.mod/gen/k8s.io

The modified module directory should like:

├── cue.mod
│ ├── gen
│ │ └── k8s.io
│ │ ├── api
│ │ │ ├── apps
│ │ │ └── core
│ │ ├── apimachinery
│ │ │ └── pkg
│ │ ├── apps
│ │ └── core
│ ├── module.cue
│ ├── pkg
│ └── usr
├── def.cue
├── go.mod
└── go.sum

So, you can import the package use the following path that aligns with KubeVela:

import (
apps "k8s.io/apps/v1"
corev1 "k8s.io/core/v1"
)
  1. Test and Run.

Finally, we can test CUE Template which use the Kube package.

import (
apps "k8s.io/apps/v1"
corev1 "k8s.io/core/v1"
)
// output is validated by Deployment.
output: apps.#Deployment
output: {
metadata: {
name: context.name
namespace: "default"
}
spec: {
selector: matchLabels: {
"app": context.name
}
template: {
metadata: {
labels: {
"app": context.name
"version": parameter.version
}
}
spec: {
terminationGracePeriodSeconds: parameter.podShutdownGraceSeconds
containers: [{
name: context.name
image: parameter.image
ports: [{
if parameter.containerPort != _|_ {
containerPort: parameter.containerPort
}
if parameter.containerPort == _|_ {
containerPort: parameter.servicePort
}
}]
if parameter.env != _|_ {
env: [
for k, v in parameter.env {
name: k
value: v
},
]
}
resources: {
requests: {
if parameter.cpu != _|_ {
cpu: parameter.cpu
}
if parameter.memory != _|_ {
memory: parameter.memory
}
}
}
}]
}
}
}
}
outputs:{
service: corev1.#Service
}
// Service
outputs: service: {
metadata: {
name: context.name
labels: {
"app": context.name
}
}
spec: {
//type: "ClusterIP"
selector: {
"app": context.name
}
ports: [{
port: parameter.servicePort
if parameter.containerPort != _|_ {
targetPort: parameter.containerPort
}
if parameter.containerPort == _|_ {
targetPort: parameter.servicePort
}
}]
}
}
parameter: {
version: *"v1" | string
image: string
servicePort: int
containerPort?: int
// +usage=Optional duration in seconds the pod needs to terminate gracefully
podShutdownGraceSeconds: *30 | int
env: [string]: string
cpu?: string
memory?: string
}
// mock context data
context: {
name: "test"
}
// mock parameter data
parameter: {
image: "test-image"
servicePort: 8000
env: {
"HELLO": "WORLD"
}
}

Use cue export to see the export result.

$ cue export def.cue --out yaml
output:
metadata:
name: test
namespace: default
spec:
selector:
matchLabels:
app: test
template:
metadata:
labels:
app: test
version: v1
spec:
terminationGracePeriodSeconds: 30
containers:
- name: test
image: test-image
ports:
- containerPort: 8000
env:
- name: HELLO
value: WORLD
resources:
requests: {}
outputs:
service:
metadata:
name: test
labels:
app: test
spec:
selector:
app: test
ports:
- port: 8000
targetPort: 8000
parameter:
version: v1
image: test-image
servicePort: 8000
podShutdownGraceSeconds: 30
env:
HELLO: WORLD
context:
name: test

Dry-Run the Application#

When CUE template is good, we can use vela system dry-run to dry run and check the rendered resources in real Kubernetes cluster. This command will exactly execute the same render logic in KubeVela's Application Controller and output the result for you.

First, we need use mergedef.sh to merge the definition and cue files.

$ mergedef.sh def.yaml def.cue > componentdef.yaml

Then, let's create an Application named test-app.yaml.

apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
name: boutique
namespace: default
spec:
components:
- name: frontend
type: microservice
properties:
image: registry.cn-hangzhou.aliyuncs.com/vela-samples/frontend:v0.2.2
servicePort: 80
containerPort: 8080
env:
PORT: "8080"
cpu: "100m"
memory: "64Mi"

Dry run the application by using vela system dry-run.

$ vela system dry-run -f test-app.yaml -d componentdef.yaml
---
# Application(boutique) -- Comopnent(frontend)
---
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app.oam.dev/component: frontend
app.oam.dev/name: boutique
workload.oam.dev/type: microservice
name: frontend
namespace: default
spec:
selector:
matchLabels:
app: frontend
template:
metadata:
labels:
app: frontend
version: v1
spec:
containers:
- env:
- name: PORT
value: "8080"
image: registry.cn-hangzhou.aliyuncs.com/vela-samples/frontend:v0.2.2
name: frontend
ports:
- containerPort: 8080
resources:
requests:
cpu: 100m
memory: 64Mi
serviceAccountName: default
terminationGracePeriodSeconds: 30
---
apiVersion: v1
kind: Service
metadata:
labels:
app: frontend
app.oam.dev/component: frontend
app.oam.dev/name: boutique
trait.oam.dev/resource: service
trait.oam.dev/type: AuxiliaryWorkload
name: frontend
spec:
ports:
- port: 80
targetPort: 8080
selector:
app: frontend
type: ClusterIP
---

-d or --definitions is a useful flag 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. If the capability is not found in local files and cluster, it will raise an error.

Live-Diff the Application#

vela system live-diff allows users to have a preview of what would change if upgrade an application. It basically generates a diff between the specific revision of an application and the result of vela system dry-run. The result shows the changes (added/modified/removed/no_change) of the application as well as its sub-resources, such as components and traits. live-diff will not make any changes to the living cluster, so it's very helpful if you want to update an application but worry about the unknown results that may be produced.

Let's prepare an application and deploy it.

ComponentDefinitions and TraitDefinitions used in this sample are stored in ./doc/examples/live-diff/definitions.

# app.yaml
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
name: livediff-demo
spec:
components:
- name: myweb-1
type: myworker
properties:
image: "busybox"
cmd:
- sleep
- "1000"
lives: "3"
enemies: "alien"
traits:
- type: myingress
properties:
domain: "www.example.com"
http:
"/": 80
- type: myscaler
properties:
replicas: 2
- name: myweb-2
type: myworker
properties:
image: "busybox"
cmd:
- sleep
- "1000"
lives: "3"
enemies: "alien"
kubectl apply ./doc/examples/live-diff/definitions
kubectl apply ./doc/examples/live-diff/app.yaml

Then, assume we want to update the application with below configuration. To preview changes brought by updating while not really apply updated configuration into the cluster, we can use live-diff here.

# app-updated.yaml
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
name: livediff-demo
spec:
components:
- name: myweb-1
type: myworker
properties:
image: "busybox"
cmd:
- sleep
- "2000" # change a component property
lives: "3"
enemies: "alien"
traits:
- type: myingress
properties:
domain: "www.example.com"
http:
"/": 90 # change a trait
# - type: myscaler # remove a trait
# properties:
# replicas: 2
- name: myweb-2
type: myworker
properties: # no change on component property
image: "busybox"
cmd:
- sleep
- "1000"
lives: "3"
enemies: "alien"
traits:
- type: myingress # add a trait
properties:
domain: "www.example.com"
http:
"/": 90
- name: myweb-3 # add a component
type: myworker
properties:
image: "busybox"
cmd:
- sleep
- "1000"
lives: "3"
enemies: "alien"
traits:
- type: myingress
properties:
domain: "www.example.com"
http:
"/": 90
vela system live-diff -f ./doc/examples/live-diff/app-modified.yaml -r livediff-demo-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 diff result
---
# Application (application-sample) has been modified(*)
---
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
creationTimestamp: null
- name: application-sample
+ name: livediff-demo
namespace: default
spec:
components:
- name: myweb-1
+ properties:
+ cmd:
+ - sleep
+ - "2000"
+ enemies: alien
+ image: busybox
+ lives: "3"
+ traits:
+ - properties:
+ domain: www.example.com
+ http:
+ /: 90
+ type: myingress
+ type: myworker
+ - name: myweb-2
properties:
cmd:
- sleep
- "1000"
enemies: alien
image: busybox
lives: "3"
traits:
- properties:
domain: www.example.com
http:
- /: 80
+ /: 90
type: myingress
- - properties:
- replicas: 2
- type: myscaler
type: myworker
- - name: myweb-2
+ - name: myweb-3
properties:
cmd:
- sleep
- "1000"
enemies: alien
image: busybox
lives: "3"
+ traits:
+ - properties:
+ domain: www.example.com
+ http:
+ /: 90
+ type: myingress
type: myworker
status:
batchRollingState: ""
currentBatch: 0
rollingState: ""
upgradedReadyReplicas: 0
upgradedReplicas: 0
---
## Component (myweb-1) has been modified(*)
---
apiVersion: core.oam.dev/v1alpha2
kind: Component
metadata:
creationTimestamp: null
labels:
- app.oam.dev/name: application-sample
+ app.oam.dev/name: livediff-demo
name: myweb-1
spec:
workload:
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app.oam.dev/appRevision: ""
app.oam.dev/component: myweb-1
- app.oam.dev/name: application-sample
+ app.oam.dev/name: livediff-demo
workload.oam.dev/type: myworker
spec:
selector:
matchLabels:
app.oam.dev/component: myweb-1
template:
metadata:
labels:
app.oam.dev/component: myweb-1
spec:
containers:
- command:
- sleep
- - "1000"
+ - "2000"
image: busybox
name: myweb-1
status:
observedGeneration: 0
---
### Component (myweb-1) / Trait (myingress/ingress) has been modified(*)
---
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
labels:
app.oam.dev/appRevision: ""
app.oam.dev/component: myweb-1
- app.oam.dev/name: application-sample
+ app.oam.dev/name: livediff-demo
trait.oam.dev/resource: ingress
trait.oam.dev/type: myingress
name: myweb-1
spec:
rules:
- host: www.example.com
http:
paths:
- backend:
serviceName: myweb-1
- servicePort: 80
+ servicePort: 90
path: /
---
### Component (myweb-1) / Trait (myingress/service) has been modified(*)
---
apiVersion: v1
kind: Service
metadata:
labels:
app.oam.dev/appRevision: ""
app.oam.dev/component: myweb-1
- app.oam.dev/name: application-sample
+ app.oam.dev/name: livediff-demo
trait.oam.dev/resource: service
trait.oam.dev/type: myingress
name: myweb-1
spec:
ports:
- - port: 80
- targetPort: 80
+ - port: 90
+ targetPort: 90
selector:
app.oam.dev/component: myweb-1
---
### Component (myweb-1) / Trait (myscaler/scaler) has been removed(-)
---
- apiVersion: core.oam.dev/v1alpha2
- kind: ManualScalerTrait
- metadata:
- labels:
- app.oam.dev/appRevision: ""
- app.oam.dev/component: myweb-1
- app.oam.dev/name: application-sample
- trait.oam.dev/resource: scaler
- trait.oam.dev/type: myscaler
- spec:
- replicaCount: 2
---
## Component (myweb-2) has been modified(*)
---
apiVersion: core.oam.dev/v1alpha2
kind: Component
metadata:
creationTimestamp: null
labels:
- app.oam.dev/name: application-sample
+ app.oam.dev/name: livediff-demo
name: myweb-2
spec:
workload:
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app.oam.dev/appRevision: ""
app.oam.dev/component: myweb-2
- app.oam.dev/name: application-sample
+ app.oam.dev/name: livediff-demo
workload.oam.dev/type: myworker
spec:
selector:
matchLabels:
app.oam.dev/component: myweb-2
template:
metadata:
labels:
app.oam.dev/component: myweb-2
spec:
containers:
- command:
- sleep
- "1000"
image: busybox
name: myweb-2
status:
observedGeneration: 0
---
### Component (myweb-2) / Trait (myingress/ingress) has been added(+)
---
+ apiVersion: networking.k8s.io/v1beta1
+ kind: Ingress
+ metadata:
+ labels:
+ app.oam.dev/appRevision: ""
+ app.oam.dev/component: myweb-2
+ app.oam.dev/name: livediff-demo
+ trait.oam.dev/resource: ingress
+ trait.oam.dev/type: myingress
+ name: myweb-2
+ spec:
+ rules:
+ - host: www.example.com
+ http:
+ paths:
+ - backend:
+ serviceName: myweb-2
+ servicePort: 90
+ path: /
---
### Component (myweb-2) / Trait (myingress/service) has been added(+)
---
+ apiVersion: v1
+ kind: Service
+ metadata:
+ labels:
+ app.oam.dev/appRevision: ""
+ app.oam.dev/component: myweb-2
+ app.oam.dev/name: livediff-demo
+ trait.oam.dev/resource: service
+ trait.oam.dev/type: myingress
+ name: myweb-2
+ spec:
+ ports:
+ - port: 90
+ targetPort: 90
+ selector:
+ app.oam.dev/component: myweb-2
---
## Component (myweb-3) has been added(+)
---
+ apiVersion: core.oam.dev/v1alpha2
+ kind: Component
+ metadata:
+ creationTimestamp: null
+ labels:
+ app.oam.dev/name: livediff-demo
+ name: myweb-3
+ spec:
+ workload:
+ apiVersion: apps/v1
+ kind: Deployment
+ metadata:
+ labels:
+ app.oam.dev/appRevision: ""
+ app.oam.dev/component: myweb-3
+ app.oam.dev/name: livediff-demo
+ workload.oam.dev/type: myworker
+ spec:
+ selector:
+ matchLabels:
+ app.oam.dev/component: myweb-3
+ template:
+ metadata:
+ labels:
+ app.oam.dev/component: myweb-3
+ spec:
+ containers:
+ - command:
+ - sleep
+ - "1000"
+ image: busybox
+ name: myweb-3
+ status:
+ observedGeneration: 0
---
### Component (myweb-3) / Trait (myingress/ingress) has been added(+)
---
+ apiVersion: networking.k8s.io/v1beta1
+ kind: Ingress
+ metadata:
+ labels:
+ app.oam.dev/appRevision: ""
+ app.oam.dev/component: myweb-3
+ app.oam.dev/name: livediff-demo
+ trait.oam.dev/resource: ingress
+ trait.oam.dev/type: myingress
+ name: myweb-3
+ spec:
+ rules:
+ - host: www.example.com
+ http:
+ paths:
+ - backend:
+ serviceName: myweb-3
+ servicePort: 90
+ path: /
---
### Component (myweb-3) / Trait (myingress/service) has been added(+)
---
+ apiVersion: v1
+ kind: Service
+ metadata:
+ labels:
+ app.oam.dev/appRevision: ""
+ app.oam.dev/component: myweb-3
+ app.oam.dev/name: livediff-demo
+ trait.oam.dev/resource: service
+ trait.oam.dev/type: myingress
+ name: myweb-3
+ spec:
+ ports:
+ - port: 90
+ targetPort: 90
+ selector:
+ app.oam.dev/component: myweb-3
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Last updated on by yangsoon