Deploying Lambda function: deleteFaceFunction

Overview

This page describes how to create the deleteFaceFunction Lambda function.
It is used to remove specific faces from an Amazon Rekognition collection and optionally delete related objects from an S3 bucket.

Step 1: Create the Lambda function

  1. Still in Lambda console, navigate to functions.

  2. Choose Create function.

  3. Under Author from scratch:

    • Function name: deleteFaceFunction
    • Runtime: Node.js 22.x
    • Architecture: x86_64

Other Additional configurations can be left alone.

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  1. Choose Create function.

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Step 2: Add the function code

  1. In the Code tab, replace the default code with the handler from your Amplify project:

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Or copy the handler.js file from:
Amplify/functions/deleteFaceFunction/handler.js

import { DeleteFacesCommand } from "@aws-sdk/client-rekognition";
import { DeleteObjectCommand } from "@aws-sdk/client-s3";
import { RekognitionClient } from "@aws-sdk/client-rekognition";
import { S3Client } from "@aws-sdk/client-s3";

export const CONSTANTS = {
  LIVENESS_CONFIDENCE_THRESHOLD: 85,
  FACE_MATCH_THRESHOLD: 70,
  MANUAL_CHECKIN_THRESHOLD: 90,
  PREVIEW_CLEANUP_DELAY: 5 * 60 * 1000, // 5 minutes
};

const clientConfig = {
  region: process.env.AWS_REGION || "us-east-1",
  credentials: {
    accessKeyId: process.env.AWS_ACCESS_KEY_ID,
    secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY,
  },
};

export const s3Client = new S3Client(clientConfig);
export const rekognitionClient = new RekognitionClient(clientConfig);

class RekognitionService {
  static async deleteFaces(collectionId, faceIds) {
    const command = new DeleteFacesCommand({
      CollectionId: collectionId,
      FaceIds: faceIds,
    });

    return await rekognitionClient.send(command);
  }
}

class S3Service {
  static async deleteObject(bucket, key) {
    const command = new DeleteObjectCommand({
      Bucket: bucket,
      Key: key,
    });

    return await s3Client.send(command);
  }
}

export const handler = async (event) => {
  try {
    let body = event.body;

    // Nếu body là JSON string -> parse
    if (typeof body === "string") {
      try {
        body = JSON.parse(body);
      } catch {
        return {
          statusCode: 400,
          body: JSON.stringify({ success: false, error: "Invalid JSON body" }),
        };
      }
    }

    const { faceId, s3Key } = body || {};

    if (!faceId || !s3Key) {
      return {
        statusCode: 400,
        body: JSON.stringify({
          success: false,
          error: "Missing faceId or s3Key",
        }),
      };
    }

    // 1. Delete from Rekognition
    await RekognitionService.deleteFaces(process.env.REKOGNITION_COLLECTION, [
      faceId,
    ]);

    // 2. Delete from S3
    await S3Service.deleteObject(process.env.S3_BUCKET, s3Key);

    return {
      statusCode: 200,
      body: JSON.stringify({
        success: true,
        message: "Face and image deleted successfully",
      }),
    };
  } catch (err) {
    console.error("Error deleting face:", err);
    return {
      statusCode: 500,
      body: JSON.stringify({ success: false, error: err.message }),
    };
  }
};

Choose Deploy (or Ctrl + Shift + U) to save your changes.

Step 3: Configure environment variables

  1. In the Configuration tab, choose Environment variables.

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  1. Add the following:
S3_BUCKET=YOUR_S3_BUCKET_NAME
REKOGNITION_COLLECTION=YOUR_REKOGNITION_COLLECTION_NAME
DYNAMO_TABLE=YOUR_DYNAMO_TABLE_NAME

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  1. Save changes.

Step 4: Assign IAM permissions

Your Lambda function needs permission to delete faces in a Rekognition collection and remove objects from S3.

  1. Still in the Configuration tab, go to Permissions and click the role name attached to your Lambda function.

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  1. This will open the IAM console — choose Add permissions → Create inline policy.

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  1. Switch to JSON view and paste:
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": "rekognition:DeleteFaces",
      "Resource": "arn:aws:rekognition:AWS_REGION:UserId:collection/ColectionName"
    },
    {
      "Effect": "Allow",
      "Action": "s3:DeleteObject",
      "Resource": "arn:aws:s3:::YOUR_S3_BUCKET_NAME/*"
    }
  ]
}

Replace YOUR_S3_BUCKET_NAME with your actual bucket name. The arn:aws:s3::: format should exactly match your bucket. As well as AWS REGION, UserId (AWS Account ID) and CollectionName as your Rekognition collection name

  1. Save the policy and attach it to your Lambda execution role.

At this point, deleteFaceFunction is ready to be integrated into your system to remove specific faces and associated objects.