sim-lambda-runtime-provided-sdk.example.ts

/**
 * Simulated Lambda function code reading sim S3 through the
 * runtime-provided AWS SDK, authorized as its execution role.
 */

import { CreateRoleCommand, PutRolePolicyCommand } from "@aws-sdk/client-iam";
import { CreateFunctionCommand, InvokeCommand } from "@aws-sdk/client-lambda";
import { CreateBucketCommand, PutObjectCommand } from "@aws-sdk/client-s3";

import { SimAws } from "@kensio/yulin";
import { makeLambdaCodeZip } from "@kensio/yulin/lambda";

const simAws = new SimAws();

// An object for the function to read.
await simAws
  .s3()
  .createBucket(new CreateBucketCommand({ Bucket: "data-bucket" }));
await simAws.s3().putObject(
  new PutObjectCommand({
    Bucket: "data-bucket",
    Key: "greeting.txt",
    Body: "Hello from S3",
  }),
);

// An execution role allowed to read it.
const roleCreation = await simAws.iam().createRole(
  new CreateRoleCommand({
    RoleName: "ReaderRole",
    AssumeRolePolicyDocument: JSON.stringify({
      Version: "2012-10-17",
      Statement: {
        Effect: "Allow",
        Principal: { Service: "lambda.amazonaws.com" },
        Action: "sts:AssumeRole",
      },
    }),
  }),
);
await simAws.iam().putRolePolicy(
  new PutRolePolicyCommand({
    RoleName: "ReaderRole",
    PolicyName: "ReadDataBucket",
    PolicyDocument: JSON.stringify({
      Version: "2012-10-17",
      Statement: {
        Effect: "Allow",
        Action: "s3:GetObject",
        Resource: "arn:aws:s3:::data-bucket/*",
      },
    }),
  }),
);

// Function code using the runtime-provided AWS SDK.
await simAws.lambda().createFunction(
  new CreateFunctionCommand({
    FunctionName: "reader",
    Role: roleCreation.Role.Arn,
    Handler: "index.handler",
    Code: {
      ZipFile: makeLambdaCodeZip(`
        const { S3Client, GetObjectCommand } = require("@aws-sdk/client-s3");
        const s3Client = new S3Client({});
        exports.handler = async (event) => {
          const output = await s3Client.send(
            new GetObjectCommand({
              Bucket: "data-bucket",
              Key: event.objectKey,
            }),
          );
          return await output.Body.transformToString();
        };
      `),
    },
  }),
);

const output = await simAws.lambda().invoke(
  new InvokeCommand({
    FunctionName: "reader",
    Payload: JSON.stringify({ objectKey: "greeting.txt" }),
  }),
);

if (output.Payload === undefined) throw new Error("No invoke Payload");
console.log(Buffer.from(output.Payload).toString());

await simAws.backgroundTasksComplete();