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Initialize environment

This case will introduce what is environment and how to initialize an environment.

What is environment#

An Application development team usually needs to initialize some shared environment for users. An environment is a logical concept that represents a set of common resources for Applications.

For example, a team usually wants two environments: one for development, and one for production.

In general, the resource types that can be initialized include the following types:

  1. One or more Kubernetes clusters. Different environments may need different sizes and versions of Kubernetes clusters. Environment initialization can also manage multiple clusters .

  2. Any type of Kubernetes custom resources (CRDS) and system plug-ins can be set up in environment initialization.

  3. All kinds of shared resources and services. For example. shared resources in microservices. These shared resources can be a microservice component, cloud database, cache, load balancer, API gateway, and so on.

  4. Various management policies and processes. An environment may have different global policies. The policy can be chaos test, security scan, SLO and son on; the process can be initializing a database table, registering an automatic discovery configuration, and so on.

KubeVela allows you to use different resources to initialize the environment.

You can use the Policy and Workflow in your Application. Note that there may be dependencies between initializations, we can use depends-on-app in workflow to do it.

The initialization of different environments has dependencies. Common resources can be separated as dependencies. In this way, reusable initialization modules can be formed.

For example, if both the test and develop environments rely on the same controllers, these controllers can be pulled out and initialized as separate environments, specifying dependency initialization in both the development and test environments.

How to use#

Directly use Application for initialization#

Make sure your KubeVela version is v1.1.6+.

If we want to use some CRD controller like OpenKruise in cluster, we can use Helm to initialize kruise.

We can directly use Application to initialize a kruise environment. The application below will deploy a kruise controller in cluster.

We have to enable fluxcd in cluster since we use Helm to deploy kruise. We can use depends-on-app to make sure fluxcd is deployed before kruise.

depends-on-app will check if the cluster has the application with name and namespace defines in properties. If the application exists, the next step will be executed after the application is running. If the application do not exists, KubeVela will check the ConfigMap with the same name, and read the config of the Application and apply to cluster. For more information, please refer to depends-on-app.

cat <<EOF | kubectl apply -f -
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
name: kruise
namespace: vela-system
spec:
components:
- name: kruise
type: helm
properties:
branch: master
chart: ./charts/kruise/v0.9.0
version: "*"
repoType: git
url: https://github.com/openkruise/kruise
workflow:
steps:
- name: check-flux
type: depends-on-app
properties:
name: fluxcd
namespace: vela-system
- name: apply-kruise
type: apply-component
properties:
component: kruise
EOF

Check the application in cluster:

$ vela ls -n vela-system
APP COMPONENT TYPE TRAITS PHASE HEALTHY STATUS CREATED-TIME
kruise ... raw running healthy 2021-09-24 20:59:06 +0800 CST
fluxcd ... raw running healthy 2021-09-24 20:59:06 +0800 CST

Kruise is running successfully! Then you can use kruise in your cluster. If you need to set up a new environment, the only thing you need to do is to apply the files like above.

Add initialize workflow in application#

Some Kubernetes native resources like ConfigMap/PVC are commonly used in the environment.

If you want to apply those resources before deploying your application, you can add an initialization workflow to your application.

KubeVela provides a built-in workflow step apply-object to fill in native Kubernetes resources. In this way, by filling in Kubernetes native resources, we can avoid writing redundant component definitions.

Apply the following application, it will initialize an environment with ConfigMap/PVC. There is two components in this application, the first one will write data to PVC, the second on will read the data from PVC:

apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
name: server-with-pvc-and-cm
namespace: default
spec:
components:
- name: log-gen-worker
type: worker
properties:
image: busybox
cmd:
- /bin/sh
- -c
- >
i=0;
while true;
do
echo "$i: $(date)" >> /test-pvc/date.log;
i=$((i+1));
sleep 1;
done
volumes:
- name: "my-pvc"
type: "pvc"
mountPath: "/test-pvc"
claimName: "my-claim"
- name: "my-configmap"
type: "configMap"
mountPath: "/test-cm"
cmName: "my-cm"
items:
- key: test-key
path: test-key
- name: log-read-worker
type: worker
properties:
name: count-log
image: busybox
cmd:
- /bin/sh
- -c
- 'tail -n+1 -f /test-pvc/date.log'
volumes:
- name: "my-pvc"
type: "pvc"
mountPath: "/test-pvc"
claimName: "my-claim"
- name: "my-configmap"
type: "configMap"
mountPath: "/test-cm"
cmName: "my-cm"
items:
- key: test-key
path: test-key
workflow:
steps:
- name: apply-pvc
type: apply-object
properties:
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: my-claim
namespace: default
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 8Gi
storageClassName: standard
- name: apply-cm
type: apply-object
properties:
apiVersion: v1
kind: ConfigMap
metadata:
name: my-cm
namespace: default
data:
test-key: test-value
- name: apply-remaining
type: apply-remaining

Check the PVC and ConfigMap in cluster:

$ kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
my-claim Bound pvc-2621d7d7-453c-41df-87fb-58e6b3a8e136 8Gi RWO standard 2m53s
$ kubectl get cm
NAME DATA AGE
my-cm 1 3m8s

Check the application in cluster:

$ vela ls
APP COMPONENT TYPE TRAITS PHASE HEALTHY STATUS CREATED-TIME
server-with-pvc-and-cm log-gen-worker worker running healthy 2021-10-11 20:42:38 +0800 CST
└─ log-read-worker worker running 2021-10-11 20:42:38 +0800 CST

Check the logs of the second component:

$ kubectl logs -f log-read-worker-774b58f565-ch8ch
0: Mon Oct 11 12:43:01 UTC 2021
1: Mon Oct 11 12:43:02 UTC 2021
2: Mon Oct 11 12:43:03 UTC 2021
3: Mon Oct 11 12:43:04 UTC 2021
4: Mon Oct 11 12:43:05 UTC 2021
5: Mon Oct 11 12:43:06 UTC 2021
6: Mon Oct 11 12:43:07 UTC 2021
7: Mon Oct 11 12:43:08 UTC 2021

We can see that both components is running. The two components share the same PVC and use the same ConfigMap.

Last updated on by Tianxin Dong