s3m a command-line tool for storing streams of data in s3 buckets.

There are streams of data that can not be lost besides that when created, they degrade the performance of running systems, for example, if the stream is a backup of a database, every time the stream is produced it may lock the entire cluster (depends on the options and tools used mysqldump/xtrabackup for example), however, the effort to create the stream is proportional to the size of the database, in most cases the bigger the database is the more time and CPU and Memory are required.

In the case of backups, normally the streams are piped to a compression tool and later put in the disk, in some cases writing to the existing disk where the database is or to a remote mount endpoint, is not possible due to size constraints and the compressed backup should be streamed to am s3 bucket (X provider), therefore if for some reason the connection gets lost while streaming almost before finishing, the whole backup procedure could be corrupted and in worst scenario everything should start all over again.

The aim of s3m apart from trying to consume fewer resources is to make as much as possible "fault-tolerant" the storage procedure of the incoming stream so that even if the server lost network connectivity, the stream can be resumed and continue the upload process where it was left without the need to start all over again (no when input is from STDIN/pipe).

https://s3m.stream

s3m is designed to run in very constrained environments with minimal resource usage:

• Disk Space: 512MB when streaming from STDIN (for buffering multipart uploads)
• Memory: Minimal - uses streaming to avoid loading data into RAM
• Network: Internet connection for S3 uploads (supports resumable uploads on disconnection)

Create ~/.config/s3m/config.yml:

hosts:
  s3:
    endpoint: s3.us-west-2.amazonaws.com
    access_key: YOUR_ACCESS_KEY
    secret_key: YOUR_SECRET_KEY
    bucket: my-bucket  # optional default bucket

hosts:
  aws:
    region: us-west-1
    access_key: AWS_KEY
    secret_key: AWS_SECRET

  backblaze:
    endpoint: s3.us-west-000.backblazeb2.com
    access_key: B2_KEY
    secret_key: B2_SECRET

s3m uses the format: /host/bucket/file

# Upload file
s3m file.dat /s3/my-bucket/

# Upload with different name
s3m local-file.dat /s3/my-bucket/remote-name.dat

# Stream from STDIN
mariadb-dump database | s3m --pipe /s3/backups/db-backup.sql

s3m get /s3/my-bucket/file.dat

# List all buckets
s3m ls s3

# List objects in bucket
s3m ls s3/my-bucket

# List with prefix
s3m ls s3/my-bucket/path/

s3m cb s3/new-bucket

# Delete object
s3m rm s3/my-bucket/file.dat

# Delete bucket
s3m rm -b s3/empty-bucket

# Compress before upload (uses Zstandard)
s3m --compress mysqldump.sql s3/backups/db.sql.zst

# Generate secure encryption key (32 characters)
openssl rand -hex 16 > encryption.key

# Encrypt during upload
s3m --encrypt --enc-key "$(cat encryption.key)" file.dat s3/secure/file.dat.enc

# Decrypt during download
s3m get s3/secure/file.dat.enc --enc-key "$(cat encryption.key)"

# Adjust part size for multipart uploads (in MB)
s3m --buffer 50 big-file.dat s3/large/huge-file.dat

# Limit upload speed (in KB/s)
s3m --throttle 10240 file.dat s3/backups/file.dat  # 10MB/s

# Configure retry attempts for failed parts
s3m --retries 5 file.dat s3/bucket/file.dat

# Unit tests (255 tests)
cargo test

# Integration tests with MinIO (Podman)
just container            # start MinIO (idempotent)
just test-integration     # run ignored e2e tests against that MinIO
# or in one go
just container test-integration
# full suite (fmt + clippy + unit + integration)
just test
# stop/clean the container
podman rm -f s3m-test-minio

Example config.yml for the default MinIO container:

---
hosts:
  minio:
    endpoint: http://localhost:9000
    access_key: minioadmin
    secret_key: minioadmin

cargo install cargo-llvm-cov
cargo llvm-cov --all-features --workspace

Coverage: 80%+ with 255+ tests

1. Write tests for new features
2. Run: just test (to run the containerized integration tests)
3. Run: cargo clippy --all-targets --all-features
4. Run: cargo fmt