Cloud service

In this tutorial, we will add a Alibaba Cloud’s RDS service as a new workload type in KubeVela.

Step 1: Install and configure Crossplane

We use Crossplane as the cloud resource operator for Kubernetes. This tutorial has been verified with Crossplane version 0.14. Please follow the Crossplane Documentation, especially the Install & Configure and Compose Infrastructure sections to configure Crossplane with your cloud account.

Note: When installing crossplane helm chart, please don’t set alpha.oam.enabled=true as OAM crds are already installed by KubeVela.

Step 2: Add Workload Definition

First, register the rds workload type to KubeVela.

$ cat << EOF | kubectl apply -f -
apiVersion: core.oam.dev/v1alpha2
kind: WorkloadDefinition
metadata:
  name: rds
  annotations:
    definition.oam.dev/apiVersion: "database.example.org/v1alpha1"
    definition.oam.dev/kind: "PostgreSQLInstance"
    definition.oam.dev/description: "RDS on Ali Cloud"
spec:
  definitionRef:
    name: rds.apps
  extension:
    template: |
      output: {
        apiVersion: "database.example.org/v1alpha1"
        kind: "PostgreSQLInstance"
        metadata:
          name: context.name
        spec: {
          parameters:
            storageGB: parameter.storage
          compositionSelector: {
            matchLabels:
              provider: parameter.provider
          }
          writeConnectionSecretToRef:
            name: parameter.secretname
        }
      }
      parameter: {
        secretname: *"db-conn" | string
        provider: *"alibaba" | string
        storage: *20 | int
      }
EOF

Check if the new workload type is added:

$ vela workloads
Synchronizing capabilities from cluster⌛ ...
Sync capabilities successfully ✅ Add(1) Update(0) Delete(0)
TYPE    CATEGORY    DESCRIPTION     
+rds    workload    RDS on Ali Cloud
Listing workload capabilities ...
NAME          DESCRIPTION                             
rds           RDS on Ali Cloud                        
task          One-time task/job                       
webservice    Long running service with network routes
worker        Backend worker without ports exposed

Step 3: Try out RDS workload to an application

Let’s first create an Appfile. We will claim an RDS instance with workload type of rds. You may need to change the variables of the database service to reflect your configuration.

$ cat << EOF > vela.yaml
name: test-rds
services:
  database:
    type: rds
    name: alibabaRds
    storage: 20
  checkdb:
    type: webservice
    image: nginx
    name: checkdb
    env:
      - name: PGDATABASE
        value: postgres
      - name: PGHOST
        valueFrom:
          secretKeyRef:
            name: db-conn
            key: endpoint
      - name: PGUSER
        valueFrom:
          secretKeyRef:
            name: db-conn
            key: username
      - name: PGPASSWORD
        valueFrom:
          secretKeyRef:
            name: db-conn
            key: password
      - name: PGPORT
        valueFrom:
          secretKeyRef:
            name: db-conn
            key: port
EOF

Next, we could deploy the application with $ vela up.

Verify the database status

The database provision will take some time (> 5 min) to be ready. In our Appfile, we created another service called checkdb. The database will write all the connecting credentials in a secret which we put into the checkdb service as environmental variables. To verify the database configuration, we simply print out the environmental variables of the checkdb service:
$ vela exec test-rds -- printenv
After confirming the service is checkdb, we shall see the printout of the database information:

PGUSER=myuser
PGPASSWORD=<password>
PGPORT=1921
PGDATABASE=postgres
PGHOST=<hostname>
...