AWS CloudFormation · Schema

AWS CloudFormation Template

Represents the structure of an AWS CloudFormation template. A template is a JSON or YAML formatted text file that describes the AWS infrastructure and resources to provision. Templates can be used to create and update CloudFormation stacks.

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Properties

Name	Type	Description
AWSTemplateFormatVersion	string	The AWS CloudFormation template version that the template conforms to. The only valid value is 2010-09-09.
Description	string	A text string that describes the template.
Metadata	object	Objects that provide additional information about the template. Can include template-specific metadata such as AWS::CloudFormation::Interface.
Parameters	object	Values to pass to your template at runtime when you create or update a stack. Parameters enable you to customize stack creation.
Rules	object	Validates a parameter or a combination of parameters passed to a template during stack creation or update.
Mappings	object	A mapping of keys and associated values that you can use to specify conditional parameter values. Similar to a lookup table.
Conditions	object	Conditions that control whether certain resources are created or whether certain resource properties are assigned a value during stack creation or update.
Transform	object	For serverless applications, specifies the version of the AWS SAM to use. You can also use AWS::Include transforms to work with template snippets stored separately.
Resources	object	Specifies the stack resources and their properties, such as an Amazon EC2 instance or an Amazon S3 bucket. You must declare each resource separately.
Outputs	object	Describes the values that are returned whenever you view your stack's properties. Output values can be used for cross-stack references.

View JSON Schema on GitHub

JSON Schema

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://schemas.api.aws/cloudformation/template.json",
  "title": "AWS CloudFormation Template",
  "description": "Represents the structure of an AWS CloudFormation template. A template is a JSON or YAML formatted text file that describes the AWS infrastructure and resources to provision. Templates can be used to create and update CloudFormation stacks.",
  "type": "object",
  "required": [
    "Resources"
  ],
  "properties": {
    "AWSTemplateFormatVersion": {
      "type": "string",
      "description": "The AWS CloudFormation template version that the template conforms to. The only valid value is 2010-09-09.",
      "const": "2010-09-09"
    },
    "Description": {
      "type": "string",
      "description": "A text string that describes the template.",
      "maxLength": 1024
    },
    "Metadata": {
      "type": "object",
      "description": "Objects that provide additional information about the template. Can include template-specific metadata such as AWS::CloudFormation::Interface.",
      "additionalProperties": true
    },
    "Parameters": {
      "type": "object",
      "description": "Values to pass to your template at runtime when you create or update a stack. Parameters enable you to customize stack creation.",
      "additionalProperties": {
        "$ref": "#/$defs/ParameterDefinition"
      }
    },
    "Rules": {
      "type": "object",
      "description": "Validates a parameter or a combination of parameters passed to a template during stack creation or update.",
      "additionalProperties": {
        "$ref": "#/$defs/Rule"
      }
    },
    "Mappings": {
      "type": "object",
      "description": "A mapping of keys and associated values that you can use to specify conditional parameter values. Similar to a lookup table.",
      "additionalProperties": {
        "type": "object",
        "additionalProperties": {
          "type": "object",
          "additionalProperties": true
        }
      }
    },
    "Conditions": {
      "type": "object",
      "description": "Conditions that control whether certain resources are created or whether certain resource properties are assigned a value during stack creation or update.",
      "additionalProperties": true
    },
    "Transform": {
      "description": "For serverless applications, specifies the version of the AWS SAM to use. You can also use AWS::Include transforms to work with template snippets stored separately.",
      "oneOf": [
        {
          "type": "string"
        },
        {
          "type": "array",
          "items": {
            "type": "string"
          }
        }
      ]
    },
    "Resources": {
      "type": "object",
      "description": "Specifies the stack resources and their properties, such as an Amazon EC2 instance or an Amazon S3 bucket. You must declare each resource separately.",
      "minProperties": 1,
      "additionalProperties": {
        "$ref": "#/$defs/Resource"
      }
    },
    "Outputs": {
      "type": "object",
      "description": "Describes the values that are returned whenever you view your stack's properties. Output values can be used for cross-stack references.",
      "additionalProperties": {
        "$ref": "#/$defs/OutputDefinition"
      },
      "maxProperties": 200
    }
  },
  "$defs": {
    "ParameterDefinition": {
      "type": "object",
      "description": "A template parameter declaration.",
      "required": [
        "Type"
      ],
      "properties": {
        "Type": {
          "type": "string",
          "description": "The data type for the parameter.",
          "enum": [
            "String",
            "Number",
            "List<Number>",
            "CommaDelimitedList",
            "AWS::SSM::Parameter::Type",
            "AWS::SSM::Parameter::Value<String>",
            "AWS::SSM::Parameter::Value<List<String>>",
            "AWS::SSM::Parameter::Value<CommaDelimitedList>",
            "AWS::EC2::AvailabilityZone::Name",
            "AWS::EC2::Image::Id",
            "AWS::EC2::Instance::Id",
            "AWS::EC2::KeyPair::KeyName",
            "AWS::EC2::SecurityGroup::GroupName",
            "AWS::EC2::SecurityGroup::Id",
            "AWS::EC2::Subnet::Id",
            "AWS::EC2::Volume::Id",
            "AWS::EC2::VPC::Id",
            "AWS::Route53::HostedZone::Id",
            "List<AWS::EC2::AvailabilityZone::Name>",
            "List<AWS::EC2::Image::Id>",
            "List<AWS::EC2::Instance::Id>",
            "List<AWS::EC2::SecurityGroup::GroupName>",
            "List<AWS::EC2::SecurityGroup::Id>",
            "List<AWS::EC2::Subnet::Id>",
            "List<AWS::EC2::Volume::Id>",
            "List<AWS::EC2::VPC::Id>",
            "List<AWS::Route53::HostedZone::Id>"
          ]
        },
        "Default": {
          "description": "A value of the appropriate type for the template to use if no value is specified."
        },
        "NoEcho": {
          "type": "boolean",
          "description": "Whether to mask the parameter value to prevent it from being displayed.",
          "default": false
        },
        "AllowedValues": {
          "type": "array",
          "description": "An array containing the list of values allowed for the parameter."
        },
        "AllowedPattern": {
          "type": "string",
          "description": "A regular expression that represents the patterns to allow for String types."
        },
        "MaxLength": {
          "type": "integer",
          "description": "Maximum number of characters for String types."
        },
        "MinLength": {
          "type": "integer",
          "description": "Minimum number of characters for String types."
        },
        "MaxValue": {
          "type": "number",
          "description": "Maximum numeric value for Number types."
        },
        "MinValue": {
          "type": "number",
          "description": "Minimum numeric value for Number types."
        },
        "Description": {
          "type": "string",
          "description": "A string that describes the parameter.",
          "maxLength": 4000
        },
        "ConstraintDescription": {
          "type": "string",
          "description": "A string that explains a constraint when the constraint is violated."
        }
      }
    },
    "Rule": {
      "type": "object",
      "description": "A rule that validates parameter values.",
      "properties": {
        "RuleCondition": {
          "description": "Determines when a rule takes effect."
        },
        "Assertions": {
          "type": "array",
          "description": "The assertions for the rule.",
          "items": {
            "type": "object",
            "required": [
              "Assert",
              "AssertDescription"
            ],
            "properties": {
              "Assert": {
                "description": "The assertion condition."
              },
              "AssertDescription": {
                "type": "string",
                "description": "The assertion description."
              }
            }
          }
        }
      }
    },
    "Resource": {
      "type": "object",
      "description": "A resource declaration in the template.",
      "required": [
        "Type"
      ],
      "properties": {
        "Type": {
          "type": "string",
          "description": "The resource type (e.g. AWS::EC2::Instance).",
          "pattern": "^[A-Za-z0-9]{2,64}::[A-Za-z0-9]{2,64}::[A-Za-z0-9]{2,64}$|^Custom::.+$"
        },
        "Properties": {
          "type": "object",
          "description": "Resource-specific properties.",
          "additionalProperties": true
        },
        "DependsOn": {
          "description": "Specifies that the creation of a specific resource follows another.",
          "oneOf": [
            {
              "type": "string"
            },
            {
              "type": "array",
              "items": {
                "type": "string"
              }
            }
          ]
        },
        "Condition": {
          "type": "string",
          "description": "Associates a condition with the resource so that it is created only when the condition is true."
        },
        "DeletionPolicy": {
          "type": "string",
          "description": "Determines what happens to the resource when the stack is deleted.",
          "enum": [
            "Delete",
            "Retain",
            "Snapshot",
            "RetainExceptOnCreate"
          ]
        },
        "UpdatePolicy": {
          "type": "object",
          "description": "Specifies how CloudFormation handles updates to specific resources.",
          "additionalProperties": true
        },
        "UpdateReplacePolicy": {
          "type": "string",
          "description": "Determines what happens to the resource when it is replaced during a stack update.",
          "enum": [
            "Delete",
            "Retain",
            "Snapshot"
          ]
        },
        "CreationPolicy": {
          "type": "object",
          "description": "Prevents a resource's status from reaching CREATE_COMPLETE until CloudFormation receives a specified number of success signals.",
          "additionalProperties": true
        },
        "Metadata": {
          "type": "object",
          "description": "Metadata to associate with the resource.",
          "additionalProperties": true
        }
      }
    },
    "OutputDefinition": {
      "type": "object",
      "description": "An output declaration in the template.",
      "required": [
        "Value"
      ],
      "properties": {
        "Description": {
          "type": "string",
          "description": "A description of the output value.",
          "maxLength": 1024
        },
        "Value": {
          "description": "The value of the property returned by the aws cloudformation describe-stacks command."
        },
        "Export": {
          "type": "object",
          "description": "The name of the resource output to be exported for cross-stack reference.",
          "properties": {
            "Name": {
              "description": "The export name."
            }
          },
          "required": [
            "Name"
          ]
        },
        "Condition": {
          "type": "string",
          "description": "Associates a condition with the output."
        }
      }
    }
  }
}