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Schemas

You can use custom Joi validation schemas to validate the following parts of stack configuration:

  • stack data
  • stack tags
  • stack parameters
  • stack name

You use the schemas property to specify which schemas Takomo should use for validation.

Example​

In this example we have specified to use myDataSchema schema to validate data configuration. For tags, we have two schemas: commonTags and environmentTag.

schemas:
  data: myDataSchema
  tags:
    - commonTags
    - name: environmentTag
      allowedValues:
        - dev
        - test
        - prod

The implementation of myDataSchema schema provider could look like this:

schemas/data.js
export default {
  name: "myDataSchema",
  init: ({ joi }) => joi.object({
    owner: joi.string().email(),
    costCenter: joi.number().required()
  }) 
}

The file exports an object with two properties name and init. The former specifies the schema's name used to refer to it from configuration files and the latter is a function that initializes the schema object.

The implementation of commonTags schema provider could look like this:

schemas/common-tags.js
export default {
  name: "commonTags",
  init: ({ joi }) => joi.object({
    project: joi.string().required()
  })
}

Finally, we have the implementation of environmentTag schema provider:

schemas/environment-tag.js
export default {
  name: "environmentTag",
  init: ({ joi, props }) => {
    return joi.object({
      environment: joi.string().valid(...props.allowedValues)
    })
  }
}

Unlike the other schema providers, its init function uses properties from the stack configuration file that are passed via the props argument.

Usage in configuration​

schemas property can be defined in:

  • stack group configuration files
  • blueprint configuration files
  • stack configuration files

Stack group config file​

When schemas property is defined in a stack group configuration file:

  • its value is merged with the value inherited from the parent stack group
  • its value is inherited by stack groups and stacks that belong under the stack group

Blueprint config file​

When schemas property is defined in a blueprint configuration file:

  • its value is merged with the value inherited from the parent stack group
  • its value is inherited by stacks that extend the blueprint

Stack config file​

When schemas property is defined in a stack configuration file:

  • if the stack extends a blueprint, its value is merged with the value inherited from the blueprint
  • otherwise, its value is merged with the value inherited from the parent stack group

Configuration merging​

Configuration merging happens when a stack group, blueprint or stack inherits schemas property but also defines schemas property of its own.

Schemas defined by the inheritor are appended to the inherited list of schemas.

Requirements​

The schemas property must satisfy these requirements:

  • Must be an object with the following optional properties: data, tags, parameters and name.