add readme

Readme.md

+# PostgreSQL Backup & Encryption Docker Container
+
+This Docker container is designed to perform backups of a PostgreSQL database, encrypt the backup, and optionally upload it to an S3 bucket. The backup is either saved locally or streamed directly to S3, based on the configuration.
+
+## Features
+
+- Performs `pg_dump` to create a backup of the PostgreSQL database.
+- Compresses and encrypts the backup using AES-256 encryption.
+- Supports streaming backups directly to an S3 bucket.
+- Configurable via environment variables.
+
+## Environment Variables
+
+The script requires several environment variables to run properly. These can be set in your `docker run` command or in a `.env` file.
+
+### Required Environment Variables:
+
+- **`POSTGRES_VERSION`**: The version of PostgreSQL (`16` or `17`).
+- **`POSTGRES_HOST`**: The hostname or IP address of the PostgreSQL server.
+- **`POSTGRES_USERNAME`**: The username to connect to the PostgreSQL database.
+- **`POSTGRES_PASSWORD`**: The password for the PostgreSQL user.
+- **`POSTGRES_DATABASE`**: The name of the database to back up.
+- **`ENCRYPTION_PASSWORD`**: The password used for AES-256 encryption.
+- **`TARGET_FOLDER`**: The target location for the backup (`local` or `s3`).
+
+### Optional S3-related Environment Variables (if `TARGET_FOLDER` is set to `s3`):
+
+- **`S3_ENDPOINT`**: The S3 endpoint (e.g., `https://s3.amazonaws.com`).
+- **`S3_BUCKET`**: The name of the S3 bucket.
+- **`S3_ACCESS_KEY`**: The access key for S3.
+- **`S3_ACCESS_SECRET`**: The secret key for S3.
+- **`S3_PATH`**: The path inside the S3 bucket where the backup will be stored (e.g., `backups/postgres`).
+- **`S3_REGION`**: The region of the S3 bucket (e.g., `us-west-2`). Defaults to `us-east-1`.
+- **`S3_USE_PATH_STYLE`**: Set to `true` to use path-style access with S3-compatible services. Defaults to `false`.
+
+## Example Usage
+
+### Running the Container with Local Backup
+
+```bash
+docker run --rm \
+  -e POSTGRES_VERSION=17 \
+  -e POSTGRES_HOST="your-postgres-host" \
+  -e POSTGRES_USERNAME="your-postgres-username" \
+  -e POSTGRES_PASSWORD="your-postgres-password" \
+  -e POSTGRES_DATABASE="your-database-name" \
+  -e ENCRYPTION_PASSWORD="your-encryption-password" \
+  -e TARGET_FOLDER="local" \
+  -v /path/to/local/backups:/backups \
+  postgres-backup
+```
+
+### Running the Container with S3 Backup
+
+docker run --rm \
+  -e POSTGRES_VERSION=17 \
+  -e POSTGRES_HOST="your-postgres-host" \
+  -e POSTGRES_USERNAME="your-postgres-username" \
+  -e POSTGRES_PASSWORD="your-postgres-password" \
+  -e POSTGRES_DATABASE="your-database-name" \
+  -e ENCRYPTION_PASSWORD="your-encryption-password" \
+  -e TARGET_FOLDER="s3" \
+  -e S3_ENDPOINT="https://s3.amazonaws.com" \
+  -e S3_BUCKET="your-s3-bucket-name" \
+  -e S3_ACCESS_KEY="your-s3-access-key" \
+  -e S3_ACCESS_SECRET="your-s3-access-secret" \
+  -e S3_PATH="backups/postgres" \
+  -e S3_REGION="us-west-2" \
+  -e S3_USE_PATH_STYLE="true" \
+  postgres-backup