Environment Specific Resources

For most of your resources, you want them to be identical across every environment (ie. dev, staging, prod). So your development environments are as close of a clone to the production environment as possible. But sometimes, you might want to customize resources based on the deployed environment.

Here are a couple of examples on how to do that.

Conditionally configure resources

For example, set a Lambda function's memory size based on the environment.

import { Function, StackContext } from "sst/constructs";

export function MyStack({ app, stack }: StackContext) {
  new Function(stack, "MyFunction", {
    handler: "src/lambda.main",
    memorySize: app.stage === "prod" ? 2048 : 256,
  });
}

Conditionally create resources

For example, run a cron job to perform a periodic task only in the prod environment.

import { Cron, StackContext } from "sst/constructs";

export function MyStack({ app, stack }: StackContext) {
  if (app.stage === "prod") {
    new Cron(stack, "Cron", {
      schedule: "rate(1 minute)",
      job: "src/lambda.main",
    });
  }

  // Add more resources
}

Conditionally create stacks

For example, only deploy a Stack in the dev environment.

stacks/index.js

export default function main(app) {
  if (app.stage === "dev") {
    new DevStack(app, "dev-stack");
  }

  // Add stacks
}

Sharing resources across stages

If you have resources in your app that have an upfront cost to provision, such as a VPC NAT Gateway or an RDS cluster, you can create that resource in one stage and reuse it in other stages.

Here is an example of creating a VPC in the dev stage, and sharing it with the dev-feature-a and dev-feature-b stages. Note that the dev stage needs to be deployed before the other stages, for them to be able to look up the deployed VPC.

import * as ec2 from "@aws-cdk/aws-ec2";
import { StackContext } from "sst/constructs";

export function MyStack({ app, stack }: StackContext) {
  let vpc;

  // Re-use VPC from the "dev" stage
  if (app.stage.startsWith("dev-feature-")) {
    const vpcId = "";
    vpc = ec2.Vpc.fromLookup(stack, "VPC", { vpcId });
  }
  // Create new VPC for other stages
  else {
    vpc = new ec2.Vpc(stack, "VPC");
  }

  return { vpc };
}