Mongodb to S3 backup.

backup.sh

#!/bin/bash
DB_NAME="mydb"
TIMESTAMP=$(date +%Y%m%d_%H%M%S)
S3_PATH="s3://my-bucket/mongodb-backup/backup-$TIMESTAMP.archive.gz"

mongodump \
  --host=localhost \
  --port=27017 \
  --username=username \
  --password=%DBpassw0rd% \
  --authenticationDatabase=admin \
  --readPreference=secondary \
  --db=$DB_NAME \
  --excludeCollection=dontbackup \
  --archive | gzip | aws s3 cp - $S3_PATH

Prerequisite: Install awscli and authenticate it. Best way to authenticate is to create an EC2 IAM role with a permission that grants S3 upload access to the required bucket and then add that IAM Role to the EC2 instance you will run this from.