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Garbage Collect

By default, KubeVela Application will recycle outdated resources when new version is deployed and confirmed to be healthy. In some cases, you may want to have more customized control to the recycle of outdated resources, where you can leverage the garbage-collect policy.

In garbage-collect policy, there are two major capabilities you can use.

Keep legacy resources#

Suppose you want to keep the resources created by the old version of the application. Use the garbage-collect policy and enable the option keepLegacyResource.

# app.yaml
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
name: first-vela-app
spec:
components:
- name: express-server
type: webservice
properties:
image: oamdev/hello-world
port: 8000
traits:
- type: ingress-1-20
properties:
domain: testsvc.example.com
http:
"/": 8000
policies:
- name: keep-legacy-resource
type: garbage-collect
properties:
keepLegacyResource: true
  1. create app
vela up -f app.yaml
$ vela ls
APP COMPONENT TYPE TRAITS PHASE HEALTHY STATUS CREATED-TIME
first-vela-app express-server webservice ingress-1-20 running healthy Ready:1/1 2022-04-06 16:20:25 +0800 CST
  1. update the app
# app1.yaml
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
name: first-vela-app
spec:
components:
- name: express-server-1
type: webservice
properties:
image: oamdev/hello-world
port: 8000
traits:
- type: ingress-1-20
properties:
domain: testsvc.example.com
http:
"/": 8000
policies:
- name: keep-legacy-resource
type: garbage-collect
properties:
keepLegacyResource: true
vela up -f app1.yaml
$ vela ls
APP COMPONENT TYPE TRAITS PHASE HEALTHY STATUS CREATED-TIME
first-vela-app express-server-1 webservice ingress-1-20 running healthy Ready:1/1 2022-04-06 16:20:25 +0800 CST

check whether legacy resources are reserved.

In the following steps, we'll use kubectl command to do some verification. You can also use vela status first-vela-app to check the aggregated application status and see if components are healthy.

$ kubectl get deploy
NAME READY UP-TO-DATE AVAILABLE AGE
express-server 1/1 1 1 10m
express-server-1 1/1 1 1 40s
$ kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
express-server ClusterIP 10.96.102.249 <none> 8000/TCP 10m
express-server-1 ClusterIP 10.96.146.10 <none> 8000/TCP 46s
$ kubectl get ingress
NAME CLASS HOSTS ADDRESS PORTS AGE
express-server <none> testsvc.example.com 80 10m
express-server-1 <none> testsvc.example.com 80 50s
$ kubectl get resourcetracker
NAME AGE
first-vela-app-default 12m
first-vela-app-v1-default 12m
first-vela-app-v2-default 2m56s
  1. delete the app
$ vela delete first-vela-app

If you hope to delete resources in one specified version, you can run kubectl delete resourcetracker first-vela-app-v1-default.

Persist resources#

You can also persist some resources, which skips the normal garbage-collect process when the application is updated.

Take the following app as an example, in the garbage-collect policy, a rule is added which marks all the resources created by the expose trait to use the onAppDelete strategy. This will keep those services until application is deleted.

$ cat <<EOF | vela up -f -
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
name: garbage-collect-app
spec:
components:
- name: hello-world
type: webservice
properties:
image: oamdev/hello-world
traits:
- type: expose
properties:
port: [8000]
policies:
- name: garbage-collect
type: garbage-collect
properties:
rules:
- selector:
traitTypes:
- expose
strategy: onAppDelete
EOF

You can find deployment and service created.

$ kubectl get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
hello-world 1/1 1 1 74s
$ kubectl get service
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
hello-world ClusterIP 10.96.160.208 <none> 8000/TCP 78s

If you upgrade the application and use a different component, you will find the old versioned deployment is deleted but the service is kept.

$ cat <<EOF | vela up -f -
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
name: garbage-collect-app
spec:
components:
- name: hello-world-new
type: webservice
properties:
image: oamdev/hello-world
traits:
- type: expose
properties:
port: [8000]
policies:
- name: garbage-collect
type: garbage-collect
properties:
rules:
- selector:
traitTypes:
- expose
strategy: onAppDelete
EOF
$ kubectl get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
hello-world-new 1/1 1 1 10s
$ kubectl get service
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
hello-world ClusterIP 10.96.160.208 <none> 8000/TCP 5m56s
hello-world-new ClusterIP 10.96.20.4 <none> 8000/TCP 13s

If you want to deploy job-like components, in which cases the resources in the component are not expected to be recycled even after the application is deleted, you can use the component type selector and set strategy to never as follows.

apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
name: garbage-collect-app
spec:
components:
- name: hello-world-new
type: job-like-component
policies:
- name: garbage-collect
type: garbage-collect
properties:
rules:
- selector:
componentTypes:
- webservice
strategy: never

An alternative selector for the component resources is the component name selector.

apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
name: create-ns-app
spec:
components:
- name: example-addon-namespace
type: k8s-objects
properties:
objects:
- apiVersion: v1
kind: Namespace
policies:
- name: garbage-collect
type: garbage-collect
properties:
rules:
- selector:
componentNames:
- example-addon-namespace
strategy: never
Last updated on by Jianbo Sun