### [Read this on the main serverless docs site](https://www.serverless.com/framework/docs/providers/aws/guide/resources) # AWS - Resources If you are using AWS as a provider for your Service, all [_Resources_](./intro.md#resources) are other AWS infrastructure resources which the AWS Lambda functions in your [_Service_](./intro.md#services) depend on, like AWS DynamoDB or AWS S3. Using the Serverless Framework, you can define the infrastructure resources you need in `serverless.yml`, and easily deploy them. ## Configuration Every stage you deploy to with `serverless.yml` using the `aws` provider is a single AWS CloudFormation stack. This is where your AWS Lambda functions and their event configurations are defined and it's how they are deployed. When you add `resources` those resources are added into your CloudFormation stack upon `serverless deploy`. Define your AWS resources in a property titled `resources`. What goes in this property is raw CloudFormation template syntax, in YAML, like this: ```yml # serverless.yml service: usersCrud provider: aws functions: resources: # CloudFormation template syntax Resources: usersTable: Type: AWS::DynamoDB::Table Properties: TableName: usersTable AttributeDefinitions: - AttributeName: email AttributeType: S KeySchema: - AttributeName: email KeyType: HASH ProvisionedThroughput: ReadCapacityUnits: 1 WriteCapacityUnits: 1 ``` You can attach any kind of resource to your CloudFormation stack. You can add `Resources`, `Outputs`. You can also use [Serverless Variables](./variables.md) for sensitive data or reusable configuration in your resources templates. Note: By supplying your resources at `resources.Resources` you may accidentally override resources as generated by the framework. To intentionally extend such resources, please use `resources.extensions`, see [Override AWS CloudFormation Resource](#override-aws-cloudformation-resource) section for more info. Note: You can now remove resource properties with null assignment. Since CloudFormation does not allow this, Serverless will strip these properties from the final template before upload. ## AWS CloudFormation Resource Reference To have consistent naming in the CloudFormation Templates that get deployed we use a standard pattern: `{Function Name}{Cloud Formation Resource Type}{Resource Name}{SequentialID, instanceId or Random String}` - `Function Name` - This is optional for Resources that should be recreated when the function name gets changed. Those resources are also called _function bound_ - `Cloud Formation Resource Type` - E.g., S3Bucket - `Resource Name` - An identifier for the specific resource, e.g. for an S3 Bucket the configured bucket name. - `SequentialID, instanceId or Random String` - For a few resources we need to add an optional sequential id, the Serverless instanceId (accessible via `${sls:instanceId}`) or a random string to identify them All resource names that are deployed by Serverless have to follow this naming scheme. The only exception (for backwards compatibility reasons) is the S3 Bucket that is used to upload artifacts so they can be deployed to your function. We're also using the term `normalizedName` or similar terms in this guide. This means dropping any characters that aren't allowed in resources names, e.g. special characters. If you have path variables in your url, they get normalized too, and there is a `Var` added implicitly. So `normalizedPath` for `POST /users/{user_id}` will be normalized to `UsersUseridVarTestPost` _Tip:_ If you are unsure how a resource is named, that you want to reference from your custom resources, you can issue a `serverless package`. This will create the CloudFormation template for your service in the `.serverless` folder (it is named `cloudformation-template-update-stack.json`). Just open the file and check for the generated resource name. | AWS Resource | Name Template | Example | | ------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | S3::Bucket | S3Bucket{normalizedBucketName} | S3BucketMybucket | | IAM::Role | IamRoleLambdaExecution | IamRoleLambdaExecution | | Lambda::Function | {normalizedFunctionName}LambdaFunction | HelloLambdaFunction | | Lambda::Version | {normalizedFunctionName}LambdaVersion{sha256} | HelloLambdaVersionr3pgoTvv1xT4E4NiCL6JG02fl6vIyi7OS1aW0FwAI | | Logs::LogGroup | {normalizedFunctionName}LogGroup | HelloLogGroup | | Lambda::Permission |

• **Schedule**: {normalizedFunctionName}LambdaPermissionEventsRuleSchedule{index}
• **CloudWatch Event**: {normalizedFunctionName}LambdaPermissionEventsRuleCloudWatchEvent{index}
• **CloudWatch Log**: {normalizedFunctionName}LambdaPermissionLogsSubscriptionFilterCloudWatchLog{index}
• **IoT**: {normalizedFunctionName}LambdaPermissionIotTopicRule{index}
• **S3**: {normalizedFunctionName}LambdaPermission{normalizedBucketName}S3
• **APIG**: {normalizedFunctionName}LambdaPermissionApiGateway
• **SNS**: {normalizedFunctionName}LambdaPermission{normalizedTopicName}SNS
• **Alexa Skill**: {normalizedFunctionName}LambdaPermissionAlexaSkill
• **Alexa Smart Home**: {normalizedFunctionName}LambdaPermissionAlexaSmartHome{index}
• **Cognito User Pool Trigger Source**: {normalizedFunctionName}LambdaPermissionCognitoUserPool{normalizedPoolId}TriggerSource{triggerSource}

|

• **Schedule**: HelloLambdaPermissionEventsRuleSchedule1
• **CloudWatch Event**: HelloLambdaPermissionEventsRuleCloudWatchEvent1
• **CloudWatch Log**: HelloLambdaPermissionLogsSubscriptionFilterCloudWatchLog1
• **IoT**: HelloLambdaPermissionIotTopicRule1
• **S3**: HelloLambdaPermissionBucketS3
• **APIG**: HelloLambdaPermissionApiGateway
• **SNS**: HelloLambdaPermissionTopicSNS
• **Alexa Skill**: HelloLambdaPermissionAlexaSkill
• **Alexa Smart Home**: HelloLambdaPermissionAlexaSmartHome1
• **Cognito User Pool Trigger Source**: HelloLambdaPermissionCognitoUserPoolMyPoolTriggerSourceCustomMessage

| | Events::Rule |

• **Schedule**: {normalizedFunctionName}EventsRuleSchedule{SequentialID}
• **CloudWatch Event**: {normalizedFunctionName}EventsRuleCloudWatchEvent{SequentialID}

|

• **Schedule**: HelloEventsRuleSchedule1
• **CloudWatch Event**: HelloEventsRuleCloudWatchEvent1

| | AWS::Logs::SubscriptionFilter | {normalizedFunctionName}LogsSubscriptionFilterCloudWatchLog{SequentialID} | HelloLogsSubscriptionFilterCloudWatchLog1 | | AWS::IoT::TopicRule | {normalizedFunctionName}IotTopicRule{SequentialID} | HelloIotTopicRule1 | | ApiGateway::RestApi | ApiGatewayRestApi | ApiGatewayRestApi | | ApiGateway::Resource | ApiGatewayResource{normalizedPath} | ApiGatewayResourceUsers | | ApiGateway::Method | ApiGatewayMethod{normalizedPath}{normalizedMethod} | ApiGatewayMethodUsersGet | | ApiGateway::Authorizer | {normalizedFunctionName}ApiGatewayAuthorizer | HelloApiGatewayAuthorizer | | ApiGateway::Deployment | ApiGatewayDeployment{instanceId} | ApiGatewayDeployment12356789 | | ApiGateway::ApiKey | ApiGatewayApiKey{OptionalNormalizedName}{SequentialID} | ApiGatewayApiKeyFree1 | | ApiGateway::UsagePlan | ApiGatewayUsagePlan{OptionalNormalizedName} | ApiGatewayUsagePlanFree | | ApiGateway::UsagePlanKey | ApiGatewayUsagePlanKey{OptionalNormalizedName}{SequentialID} | ApiGatewayUsagePlanKeyFree1 | | ApiGateway::Stage | ApiGatewayStage | ApiGatewayStage | | SNS::Topic | SNSTopic{normalizedTopicName} | SNSTopicSometopic | | SNS::Subscription | {normalizedFunctionName}SnsSubscription{normalizedTopicName} | HelloSnsSubscriptionSomeTopic | | AWS::Lambda::EventSourceMapping |

• **DynamoDB:** {normalizedFunctionName}EventSourceMappingDynamodb{tableName}
• **Kinesis:** {normalizedFunctionName}EventSourceMappingKinesis{streamName}

|

• **DynamoDB:** HelloLambdaEventSourceMappingDynamodbUsers
• **Kinesis:** HelloLambdaEventSourceMappingKinesisMystream

| | Cognito::UserPool | CognitoUserPool{normalizedPoolId} | CognitoUserPoolPoolId | ## Override AWS CloudFormation Resource You can override the specific CloudFormation resource to apply your own options (place all such extensions at `resources.extensions` section). For example, if you want to set `AWS::Logs::LogGroup` retention time to 30 days, override it with above table's `Name Template`. When you override basic resources, there are two things to keep in mind when it comes to `normalizedFunctionName`: - It should start with an uppercase character - The `-` will be changed to `Dash`, `_` will be changed to `Underscore` Here's an example: ```yml functions: write-post: handler: handler.writePost events: - http: method: post path: ${self:service}/api/posts/new cors: true resources: extensions: WriteDashPostLogGroup: Properties: RetentionInDays: '30' ``` Here's how the extension logic is defined: | Resource attribute | Operation | | --------------------- | -------------------------------------------------------------------------------------------------------------------------- | | `Condition` | Set to extension value if present. | | `CreationPolicy` | Set to extension value if present. | | `DeletionPolicy` | Set to extension value if present. | | `DependsOn` | Merge. The extension value will be added to the resource's `DependsOn` list. | | `Metadata` | Merge. If a metadata key with the same name exists in the resource, the value will be _replaced_ with the extension value. | | `Properties` | Merge. If a property with the same name exists in the resource, the value will be _replaced_ with the extension value. | | `UpdatePolicy` | Set to extension value if present. | | `UpdateReplacePolicy` | Set to extension value if present. | | _other_ | Not supported. An error will be thrown if you try to extend an unsupported attribute. | Extending using `resources.extensions` only works on the `Resources` part of the CloudFormation template.