s3-minio-presigned-post.ts

import { Client } from 'minio';

const maxAllowedSize = 1024 * 1024 * 50; // 50MB
const expireTime = 8 * 60 * 60; // 8 hour

const minioClient = new Client({
  endPoint: S3_ENDPOINT,
  port: 443,
  accessKey: S3_ACCESS_KEY,
  secretKey: S3_SECRET_KEY,
  useSSL: true,
});

function createNewLink(name: string, mime: string): Promise<PostPolicyResult> {
  return new Promise((resolve, reject) => {
    const policy = minioClient.newPostPolicy();

    const expires = new Date();
    expires.setSeconds(expireTime);
    policy.setExpires(expires);

    policy.setContentLengthRange(1, maxAllowedSize);
    policy.setBucket(S3_BUCKET_NAME);
    policy.setKey(name);
    policy.setContentType(mime);

    minioClient.presignedPostPolicy(policy, function(err, data) {
      if (err) {
        reject(err);
      }
      resolve(data);
    });
  });
}

createNewLink('myfolder/myfile.txt', 'text/csv').then(console.log);