100 lines
2.6 KiB
Markdown
100 lines
2.6 KiB
Markdown
---
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title: Data Pass Between Components
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---
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This section will introduce how to pass data between components.
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## Inputs and Outputs
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In KubeVela, we can use inputs and outputs in Components to pass data.
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### Outputs
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Outputs is made of `name` and `valueFrom`. Input will use `name` to reference output.
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We can write `valueFrom` in the following ways:
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1. Fill string value in the field, eg. `valueFrom: testString`.
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2. Use expression, eg. `valueFrom: output.metadata.name`. Note that `output` is a built-in field referring to the resource in the component that is rendered and deployed to the cluster.
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3. Use `+` to combine above two ways, the computed value will be the result, eg. `valueFrom: output.metadata.name + "testString"`.
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### Inputs
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Inputs is made of `from` and `parameterKey`. Input uses `from` to reference output, `parameterKey` is a expression that assigns the value of the input to the corresponding field.
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eg.
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1. Specify inputs:
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```yaml
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...
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- name: wordpress
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type: helm
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inputs:
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- from: mysql-svc
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parameterKey: properties.values.externalDatabase.host
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```
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2. The field parameterKey specifies the field path of the parameter key in component to be assigned after rendering:
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Which means the input value will be passed into the below properties:
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```yaml
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...
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- name: wordpress
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type: helm
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properties:
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values:
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externalDatabase:
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host: <input value>
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```
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## How to use
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In the following we will apply a WordPress server with the MySQL address passed from a MySQL component:
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```yaml
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apiVersion: core.oam.dev/v1beta1
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kind: Application
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metadata:
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name: wordpress-with-mysql
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namespace: default
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spec:
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components:
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- name: mysql
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type: helm
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outputs:
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# the output is the mysql service address
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- name: mysql-svc
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exportKey: output.metadata.name + ".default.svc.cluster.local"
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properties:
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repoType: helm
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url: https://charts.bitnami.com/bitnami
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chart: mysql
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version: "8.8.2"
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values:
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auth:
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rootPassword: mypassword
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- name: wordpress
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type: helm
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inputs:
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# set the host to mysql service address
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- from: mysql-svc
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parameterKey: properties.values.externalDatabase.host
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properties:
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repoType: helm
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url: https://charts.bitnami.com/bitnami
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chart: wordpress
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version: "12.0.3"
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values:
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mariadb:
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enabled: false
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externalDatabase:
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user: root
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password: mypassword
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database: mysql
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port: 3306
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```
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## Expected Outcome
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The WordPress with MySQL has been successfully applied. |