crustomize.yml file

Each overlay directory contains a crustomize.yml manifest describing how to build your templates. All fields are optional except base. If render or profile are specified, they override the corresponding command line flags.

The manifest supports variable expansion using the ${var} syntax. Variables are defined in the vars section of the manifest only and are not available in templates.

vars:
  env: dev
base: ../base
render: ejs
profile: my-aws-profile
stack:
  name: my-stack
  capabilities:
    - CAPABILITY_NAMED_IAM
  tags:
    Environment: ${env}
  s3Bucket: my-template-bucket
  s3Prefix: cfn-templates
params: ./params.yml
overlays:
  - ./Template.yml
  - file: ./another-overlay.yml
    arrayMerge: replace
values:
  Stage: ${env}
  Enabled: true
patches:
  - op: replace
    path: "/Resources/Path/To/Array/0/Property"
    value: some value

Fields

Field	Description
vars	Variables that are expanded in the crustomize.yml manifest only.
base	Path to a directory of base templates. Can be a local path or an s3://bucket/prefix URL.
overlays	List of overlay files to merge with the base templates.
params	Path to a params.yml file converted to JSON when applying. Can be local or s3://bucket/key.
render	Template engine (handlebars or ejs). Overrides --render if set.
profile	AWS CLI profile used by helper functions. Overrides --profile.
stack	CloudFormation stack information for deployment commands.
values	Arbitrary values accessible from templates.
patches	JSON patch operations applied after merging templates.

Crustomize JSON Schema

{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "type": "object",
  "properties": {
    "vars": {
      "type": "object",
      "additionalProperties": {
        "type": "string",
        "description": "Variable"
      }
    },
    "base": {
      "type": "string"
    },
    "overlays": {
      "type": "array",
      "items": {
        "oneOf": [
          {
            "type": "string",
            "description": "Overlay path"
          },
          {
            "type": "object",
            "properties": {
              "file": {
                "type": "string",
                "description": "Overlay path"
              },
              "arrayMerge": {
                "type": "string",
                "enum": [
                  "append",
                  "replace",
                  "prepend",
                  "crustomize"
                ]
              }
            },
            "required": [
              "file",
              "arrayMerge"
            ],
            "additionalProperties": false
          }
        ]
      }
    },
    "stack": {
      "type": "object",
      "properties": {
        "name": {
          "type": "string"
        },
        "capabilities": {
          "type": "array",
          "uniqueItems": true,
          "items": {
            "type": "string",
            "enum": [
              "CAPABILITY_IAM",
              "CAPABILITY_NAMED_IAM",
              "CAPABILITY_AUTO_EXPAND"
            ]
          }
        },
        "tags": {
          "type": "object",
          "additionalProperties": {
            "type": "string"
          }
        },
        "s3Bucket": {
          "type": "string"
        },
        "s3Prefix": {
          "type": "string"
        }
      },
      "required": [
        "name"
      ]
    },
    "params": {
      "type": "string"
    },
    "render": {
      "type": "string",
      "enum": [
        "handlebars",
        "ejs"
      ]
    },
    "profile": {
      "type": "string"
    },
    "values": {
      "type": "object",
      "not": {
        "required": [
          "base",
          "overlays"
        ]
      }
    },
    "patches": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "op": {
            "type": "string",
            "enum": [
              "add",
              "remove",
              "replace",
              "move",
              "copy",
              "test"
            ]
          },
          "path": {
            "type": "string"
          },
          "value": {}
        },
        "required": [
          "op",
          "path"
        ]
      }
    }
  },
  "required": [
    "base"
  ],
  "additionalProperties": false
}