node.js: S3 getSignedUrl and createPresignedPost example

createPresignedPost.js

const AWS = require('aws-sdk');
const FormData = require('form-data');

const BUCKET = 'ashish-personal-bucket';
const REGION = 'ap-southeast-2';

const fileName = 'record.json'
const fileContent = `{"dt":"${new Date().toISOString()}"}`
const fileContentType = 'application/json';

const s3 = new AWS.S3({ apiVersion: '2006-03-01', region: REGION });

function getPostUrl(key, contentType) {
  return new Promise((resolve, reject) => {
    const params = {
      Bucket: BUCKET,
      Fields: {
        key,
      },
      Expires: 100,
      Conditions: [
        ['content-length-range', 0, 10000000], // 10 Mb
        ['eq', '$Content-Type', contentType],
      ]
    };
    s3.createPresignedPost(params, (err, data) => {
      if (err) {
        reject(err);
        return;
      }
      data.fields['content-type'] = contentType;
      resolve(data);
    });
  });
}

(async () => {
  const signed = await getPostUrl(fileName, fileContentType);

  const form = new FormData();
  Object.keys(signed.fields).forEach(key => form.append(key, signed.fields[key]));

  form.append('file', Buffer.from(fileContent, 'utf-8'), {
    contentType: fileContentType
  });

  form.submit(signed.url, (err, res) => {
    if (err) {
      console.log(err);
      return;
    }
    console.log('Done', res.statusCode, res.statusMessage);
  });
})();

getSignedUrl.js

const AWS = require('aws-sdk');
const axios = require('axios');

const BUCKET = 'my-bucket';
const REGION = 'ap-southeast-2';

const fileName = 'record.json'
const fileContent = `{"dt":"${new Date().toISOString()}"}`
const fileContentType = 'application/json';

const s3 = new AWS.S3({ apiVersion: '2006-03-01', region: REGION });

(async () => {
  try {
    const presignedS3Url = s3.getSignedUrl('putObject', {
      Bucket: BUCKET,
      Key: fileName,
      ContentType: fileContentType,
    });

    const axiosResponse = await axios.put(presignedS3Url, fileContent, { headers: { 'Content-Type': fileContentType } });
    console.info(axiosResponse)
  } catch (e) {
    console.error(e)
  }
})();

S3-CORS-Policy.json

[
    {
        "AllowedHeaders": [
            "*"
        ],
        "AllowedMethods": [
            "PUT",
            "POST"
        ],
        "AllowedOrigins": [
            "*"
        ],
        "ExposeHeaders": []
    }
]