No vendor lock-in.
Copy what changed.

s3mirror copies every bucket on one S3-compatible endpoint to another. It compares objects by key and size, copies the ones that are new or a different size, and by default deletes what the source no longer has. --no-delete keeps a run copy-only.

Read the quickstart How mirroring works

$ brew tap netspeedy/s3mirror && brew install s3mirror

$ s3mirror --config config.yaml --no-delete

# after the connection checks, one section per bucket:
======================================================================
[1/2]: app-data
======================================================================
  Source: 4 objects
  Destination: 3 objects
  Actions: 3 to copy (100.8KB), 0 to delete
  ✓ Copied 3 objects in 0.0s (39.8MB/s)
  ✓ Bucket completed in 0.0s

# and the summary ends with
✓ Status: COMPLETED SUCCESSFULLY

# config.yaml
source:
  endpoint_url: "https://s3.source.example.com"
  aws_access_key_id: "SOURCE_ACCESS_KEY"
  aws_secret_access_key: "SOURCE_SECRET_KEY"
  verify_ssl: true

destination:
  endpoint_url: "https://s3.destination.example.com"
  aws_access_key_id: "DEST_ACCESS_KEY"
  aws_secret_access_key: "DEST_SECRET_KEY"
  verify_ssl: true

# from cron or a systemd timer: the full log goes to the file,
# and only errors reach the console
$ s3mirror --config /etc/s3mirror.yaml \
    --log-file /var/log/s3mirror.log

# the same run from the container image
$ docker run --rm \
    -v /etc/s3mirror.yaml:/config/config.yaml:ro \
    -v /var/log/s3mirror:/logs \
    ghcr.io/netspeedy/s3mirror:v1.0.4 \
    --config /config/config.yaml --log-file /logs/s3mirror.log

# exit code 0 means no errors were counted; alert on anything else

Browse the docs

From a first copy-only run to every config key.

Getting started

Install it and run a first, copy-only mirror.

How mirroring works

What gets copied, what gets deleted, and why.

Guides

Configure it, schedule it, run it in a container.

Reference

Look something up.