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Version: v1.0

Crossplane

云服务是应用程序的一部分。

云服务是 Component 还是 Trait?#

可以考虑以下做法:

  • 使用 ComponentDefinition 的场景:
    • 你想要允许最终用户明确声明云服务的实例并使用它,并在删除应用程序时释放该实例。
  • 使用 TraitDefinition 的场景:
    • 你不想让最终用户拥有声明或发布云服务的任何控制权,而只想给他们消费云服务,甚至可以由其他系统管理的云服务的方式。在这种情况下,会广泛使用 Service Binding 特性。

在本文档中,我们将以阿里云的 RDS(关系数据库服务)和阿里云的 OSS(对象存储服务)为例。在单个应用程序中,它们是 Traits,在多个应用程序中,它们是 Components。此机制与其他云提供商相同。

安装和配置 Crossplane#

KubeVela 使用 Crossplane 作为云服务提供商。请参阅 Installation 安装 Crossplane Alibaba provider v0.5.0。

如果你想配置任何其他 Crossplane providers,请参阅 Crossplane Select a Getting Started Configuration

$ kubectl crossplane install provider crossplane/provider-alibaba:v0.5.0
# 注意这里的 xxx 和 yyy 是你自己云资源的 AccessKey 和 SecretKey。
$ kubectl create secret generic alibaba-account-creds -n crossplane-system --from-literal=accessKeyId=xxx --from-literal=accessKeySecret=yyy
$ kubectl apply -f provider.yaml

provider.yaml 如下。

apiVersion: v1
kind: Namespace
metadata:
name: crossplane-system
---
apiVersion: alibaba.crossplane.io/v1alpha1
kind: ProviderConfig
metadata:
name: default
spec:
credentials:
source: Secret
secretRef:
namespace: crossplane-system
name: alibaba-account-creds
key: credentials
region: cn-beijing

注意:我们目前仅使用阿里提供的 Crossplane。但是在不久的将来,我们将使用 Crossplane 作为 Kubernetes 的云资源供应商。

注册 ComponentDefinition 和 TraitDefinition#

注册 ComponentDefinition alibaba-rds 为 RDS 云资源生产者#

将工作负载类型 alibaba-rds 注册到 KubeVela。

apiVersion: core.oam.dev/v1beta1
kind: ComponentDefinition
metadata:
name: alibaba-rds
namespace: vela-system
annotations:
definition.oam.dev/description: "Alibaba Cloud RDS Resource"
spec:
workload:
definition:
apiVersion: database.alibaba.crossplane.io/v1alpha1
kind: RDSInstance
schematic:
cue:
template: |
output: {
apiVersion: "database.alibaba.crossplane.io/v1alpha1"
kind: "RDSInstance"
spec: {
forProvider: {
engine: parameter.engine
engineVersion: parameter.engineVersion
dbInstanceClass: parameter.instanceClass
dbInstanceStorageInGB: 20
securityIPList: "0.0.0.0/0"
masterUsername: parameter.username
}
writeConnectionSecretToRef: {
namespace: context.namespace
name: parameter.secretName
}
providerConfigRef: {
name: "default"
}
deletionPolicy: "Delete"
}
}
parameter: {
// +usage=RDS engine
engine: *"mysql" | string
// +usage=The version of RDS engine
engineVersion: *"8.0" | string
// +usage=The instance class for the RDS
instanceClass: *"rds.mysql.c1.large" | string
// +usage=RDS username
username: string
// +usage=Secret name which RDS connection will write to
secretName: string
}

注册 ComponentDefinition alibaba-oss 为 OSS 云资源生产者#

apiVersion: core.oam.dev/v1beta1
kind: ComponentDefinition
metadata:
name: alibaba-oss
namespace: vela-system
annotations:
definition.oam.dev/description: "Alibaba Cloud RDS Resource"
spec:
workload:
definition:
apiVersion: oss.alibaba.crossplane.io/v1alpha1
kind: Bucket
schematic:
cue:
template: |
output: {
apiVersion: "oss.alibaba.crossplane.io/v1alpha1"
kind: "Bucket"
spec: {
name: parameter.name
acl: parameter.acl
storageClass: parameter.storageClass
dataRedundancyType: parameter.dataRedundancyType
writeConnectionSecretToRef: {
namespace: context.namespace
name: parameter.secretName
}
providerConfigRef: {
name: "default"
}
deletionPolicy: "Delete"
}
}
parameter: {
// +usage=OSS bucket name
name: string
// +usage=The access control list of the OSS bucket
acl: *"private" | string
// +usage=The storage type of OSS bucket
storageClass: *"Standard" | string
// +usage=The data Redundancy type of OSS bucket
dataRedundancyType: *"LRS" | string
// +usage=Secret name which RDS connection will write to
secretName: string
}

引用 Secret 注册 ComponentDefinition webconsumer#

apiVersion: core.oam.dev/v1beta1
kind: ComponentDefinition
metadata:
name: webconsumer
annotations:
definition.oam.dev/description: A Deployment provides declarative updates for Pods and ReplicaSets
spec:
workload:
definition:
apiVersion: apps/v1
kind: Deployment
schematic:
cue:
template: |
output: {
apiVersion: "apps/v1"
kind: "Deployment"
spec: {
selector: matchLabels: {
"app.oam.dev/component": context.name
}
template: {
metadata: labels: {
"app.oam.dev/component": context.name
}
spec: {
containers: [{
name: context.name
image: parameter.image
if parameter["cmd"] != _|_ {
command: parameter.cmd
}
if parameter["dbSecret"] != _|_ {
env: [
{
name: "username"
value: dbConn.username
},
{
name: "endpoint"
value: dbConn.endpoint
},
{
name: "DB_PASSWORD"
value: dbConn.password
},
]
}
ports: [{
containerPort: parameter.port
}]
if parameter["cpu"] != _|_ {
resources: {
limits:
cpu: parameter.cpu
requests:
cpu: parameter.cpu
}
}
}]
}
}
}
}
parameter: {
// +usage=Which image would you like to use for your service
// +short=i
image: string
// +usage=Commands to run in the container
cmd?: [...string]
// +usage=Which port do you want customer traffic sent to
// +short=p
port: *80 | int
// +usage=Referred db secret
// +insertSecretTo=dbConn
dbSecret?: string
// +usage=Number of CPU units for the service, like `0.5` (0.5 CPU core), `1` (1 CPU core)
cpu?: string
}
dbConn: {
username: string
endpoint: string
password: string
}

关键词是 annotation // + insertSecretTo = dbConn,KubeVela 将知道该参数是 K8s 的 secret,它将解析该 secret 并将数据绑定到 CUE 接口 dbConn 中。

output 可以引用 dbConn 获取数据。dbConn 的名称没有限制。 关键词是 +insertSecretTo,它定义了数据绑定机制。以上只是一个例子。

准备 TraitDefinition service-binding 进行 env-secret mapping#

至于应用程序中的数据绑定,KubeVela 建议定义一个 trait 以完成工作。我们已经准备了一个方便的 trait。此 trait 非常适合将资源的信息绑定到 pod spec 的环境变量中.

apiVersion: core.oam.dev/v1beta1
kind: TraitDefinition
metadata:
annotations:
definition.oam.dev/description: "binding cloud resource secrets to pod env"
name: service-binding
spec:
appliesToWorkloads:
- webservice
- worker
schematic:
cue:
template: |
patch: {
spec: template: spec: {
// +patchKey=name
containers: [{
name: context.name
// +patchKey=name
env: [
for envName, v in parameter.envMappings {
name: envName
valueFrom: {
secretKeyRef: {
name: v.secret
if v["key"] != _|_ {
key: v.key
}
if v["key"] == _|_ {
key: envName
}
}
}
},
]
}]
}
}
parameter: {
// +usage=The mapping of environment variables to secret
envMappings: [string]: [string]: string
}

借助这种 service-binding trait,开发人员可以显式设置参数 envMappings,以映射所有环境变量。例子如下。

...
traits:
- type: service-binding
properties:
envMappings:
# environments refer to db-conn secret
DB_PASSWORD:
secret: db-conn
key: password # 1) If the env name is different from secret key, secret key has to be set.
endpoint:
secret: db-conn # 2) If the env name is the same as the secret key, secret key can be omitted.
username:
secret: db-conn
# environments refer to oss-conn secret
BUCKET_NAME:
secret: oss-conn
key: Bucket
...

你可以通过查看 the end user usage workflow 了解其使用方式。

Last updated on by guoxudong