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Stack

The Stack construct extends cdk.Stack. It automatically prefixes the stack names with the stage and app name to ensure that they can be deployed to multiple regions in the same AWS account. It also ensure that the stack uses the same AWS profile and region as the app. They're defined using functions that return resources that can be imported by other stacks.

Constructor

new Stack(scope, id, props)

Parameters

Examples

Creating a new stack

import { StackContext } from "@serverless-stack/resources";

export function MyStack({ stack }: StackContext) {
// Define your stack
}

Adding to an app

Add it to your app in stacks/index.js.

import { StackA } from "./MyStack";
import { StackB } from "./MyStack";

export default function main(app) {
app
.stack(StackA)
.stack(StackB);

// Add more stacks
}

Here app is an instance of App.

Note that, setting the env for an individual stack is not allowed.

app.stack(MyStack, { env: { account: "1234", region: "us-east-1" } });

It will throw this error.

Error: Do not directly set the environment for a stack

This is by design. The stacks in SST are meant to be re-deployed for multiple stages (like Serverless Framework). And so they depend on the region and AWS profile that's passed in through the CLI. If a stack is hardcoded to be deployed to a specific account or region, it can break your deployment pipeline.

Configuring stack name

By default, the name of the CloudFormation stack is the stage name, app name, and the stack function name joined by -, ie. stage-app-MyStack.

You can override the stack function name by passing in id. In this case, the CloudFormation stack name is stage-app-my-stack.

import { MyStack } from "./MyStack";

export default function main(app) {
app.stack(MyStack, { id: "my-stack" });
}

Alternatively, you can override the CloudFormation stack name directly by passing in stackName.

import { MyStack } from "./MyStack";

export default function main(app) {
app.stack(MyStack, { stackName: `${app.stage}-my-hello-stack` });
}

Note that, stackName need to be parameterized with the stage name. This ensure an app can be deployed to multiple stages with unique stack names.

Sharing resources between stacks

Resources defined in a stack can be used by other stacks. This allows you to have granular stacks that contain only related resources.

Stack functions can return any resources they want to expose to other stacks.

import { StackContext } from "@serverless-stack/resources"

export function MyStack({ stack }: StackContext) {
const table = new Table(stack, "table")
return {
table
};
}

Other stacks can import these resources by utilizing the use function

import { StackContext, use } from "@serverless-stack/resources"
import { MyStack } from "./MyStack"

export function AnotherStack({ stack }: StackContext) {
const { table } = use(MyStack);
// Use table
}

Async stacks

Asynchronous calls are supported in stack functions but be careful when using this as you can introduce external state that makes your deployments less deterministic

Simple add an async modifier to your function definition

import { StackContext } from "@serverless-stack/resources"

export async function MyStack({ stack }: StackContext) {
const foo = await someAsynCall();
// Define stack
}

When initializing the stack, make sure you call await

import { MyStack } from "./MyStack"
export default function main(app: sst.App) {
await app.stack(MyStack);
}

Accessing app properties

The stage, region, and app name can be accessed through the app object. In your stacks (for example, stacks/MyStack.js) you can use.

function MyStack({ stack, app }: StackContext) {
app.stage;
app.region;
app.name;
}

You can use this to conditionally add stacks or resources to your app.

Specifying default function props

You can set some function props and have them apply to all the functions in a stack. This must be called before any functions have been added to the stack; so that all functions will be created with these defaults.

function MyStack({ stack }: StackContext) {
stack.setDefaultFunctionProps({
timeout: 20,
memorySize: 512,
runtime: "go1.x",
environment: { TABLE_NAME: "NOTES_TABLE" },
});
}

It'll also override any props set by the App's setDefaultFunctionProps, while merging the environment and permission props.

Updating default function props

You can also use addDefaultFunctionPermissions, addDefaultFunctionEnv, and addDefaultFunctionLayers to progressively add more permissions, environment variables, and layers to the defaults. These can be called multiple times and from anywhere.

However, they only affect the functions that are created after the call.

function MyStack({ stack }: StackContext) {
new Api(stack, "Api1", {
routes: {
"GET /": "src/hello.main",
},
});

stack.addDefaultFunctionEnv({
TABLE_NAME: "NOTES_TABLE",
});

stack.addDefaultFunctionPermissions(["s3"]);

stack.addDefaultFunctionLayers([mylayer]);

new Api(stack, "Api2", {
routes: {
"GET /": "src/world.main",
},
});
}

So in the above example, the addDefaultFunctionPermissions and addDefaultFunctionEnv calls will only impact the functions in Api2.

Prefixing resource names

You can optionally prefix resource names to make sure they don't thrash when deployed to different stages in the same AWS account.

You can do so in your stacks.

scope.logicalPrefixedName("MyResource"); // Returns "dev-my-sst-app-MyResource"

This invokes the logicalPrefixedName method in App that your stack is added to. This'll return dev-my-sst-app-MyResource, where dev is the current stage and my-sst-app is the name of the app.

Adding stack outputs

export function MyStack({ stack }: StackContext) {
const topic = new Topic(stack, "Topic");
const queue = new Queue(stack, "Queue");
stack.addOutputs({
TopicArn: topic.snsTopic.topicArn,
QueueArn: topic.sqsQueue.queueArn,
});
}

Adding stack exports

export function MyStack({ stack }: StackContext) {
const topic = new Topic(stack, "Topic");

stack.addOutputs({
TopicArn: {
value: topic.snsTopic.topicArn,
exportName: "MyTopicArn"
},
});
}

Accessing AWS account info

To access the AWS account and region your app is being deployed to, use the following in your Stack instances.

stack.region;
stack.account;

The region here is the same as the one you can find in the app instance in the constructor.

Properties

An instance of Stack has the following properties.

stage

Type : string

The current stage of the stack.

Methods

An instance of Stack has the following methods.

addDefaultFunctionEnv

addDefaultFunctionEnv(environment)

Parameters

  • environment Record<string, string>

Adds additional default environment variables to be applied to all Lambda functions in the stack.

stack.addDefaultFunctionEnv({
DYNAMO_TABLE: table.name
});

addDefaultFunctionLayers

addDefaultFunctionLayers(layers)

Parameters

Adds additional default layers to be applied to all Lambda functions in the stack.

stack.addDefaultFunctionLayers(["arn:aws:lambda:us-east-1:123456789012:layer:nodejs:3"]);

addDefaultFunctionPermissions

addDefaultFunctionPermissions(permissions)

Parameters

Adds additional default Permissions to be applied to all Lambda functions in the stack.

stack.addDefaultFunctionPermissions(["sqs", "s3"]);

addOutputs

addOutputs(outputs)

Parameters

Add outputs to this stack

stack.addOutputs({
TableName: table.name,
});
stack.addOutputs({
TableName: {
value: table.name,
exportName: "MyTableName",
}
});

getAllFunctions

getAllFunctions()

Returns all the Function instances in this stack.

stack.getAllFunctions();

setDefaultFunctionProps

setDefaultFunctionProps(props)

Parameters

The default function props to be applied to all the Lambda functions in the stack.

stack.setDefaultFunctionProps({
srcPath: "backend",
runtime: "nodejs16.x",
});