simplestreams-s3

simplestreams-s3 publishes split Incus virtual-machine images to a private Amazon S3 bucket and serves the resulting Simple Streams mirror through authenticated S3 reads, so Incus clients can list and import images without any public S3 access.

It provides three commands:

• simplestreams-s3 publish METADATA_TARBALL DISK_QCOW2 validates and publishes one split VM image. Publication is idempotent and safe under concurrent publishers; conflicts fail closed without moving the active catalog. An optional attest-vm-image evidence manifest publishes its content-addressed proofs alongside the image.
• simplestreams-s3 proxy serves exact GET and HEAD reads with ranges, conditions, readiness, JSON logging, graceful draining, and optional OTLP metrics.
• simplestreams-s3 version prints build information.

Installation

Releases publish static binaries for linux and darwin (amd64 and arm64), with checksums, SBOMs, and provenance attestations, on the releases page, plus a signed multi-architecture container image at ghcr.io/meigma/simplestreams-s3 that runs /usr/bin/simplestreams-s3 as non-root UID 65532.

To build from source with the Go toolchain pinned in mise.toml:

go build ./cmd/simplestreams-s3

Usage

Publish one split VM image (metadata tarball plus QCOW2 disk):

simplestreams-s3 publish \
  --s3-bucket private-images \
  --s3-region us-west-2 \
  incus.tar.xz disk.qcow2

Start the plain-HTTP proxy inside its trusted deployment boundary:

SIMPLESTREAMS_S3_BUCKET=private-images \
SIMPLESTREAMS_S3_REGION=us-west-2 \
simplestreams-s3 proxy --listen :8080

Both commands authenticate through the AWS SDK default credential chain; static access keys are not application settings.

GitHub Action

The repository is also a TypeScript action that installs the CLI release paired with its Git ref and publishes one split image. Authenticate to AWS first, then invoke the repository directly:

- uses: aws-actions/configure-aws-credentials@517a711dbcd0e402f90c77e7e2f81e849156e31d # v6.2.2
  with:
    role-to-assume: ${{ secrets.PUBLISH_ROLE_ARN }}
    aws-region: us-west-2

- uses: meigma/simplestreams-s3@v0
  with:
    metadata-path: build/incus.tar.xz
    disk-path: build/disk.qcow2
    s3-bucket: private-images

The optional manifest input accepts the version-1 handoff emitted by meigma/attest-vm-image. The publisher requires a passing result, verifies that the handoff binds the exact disk and metadata bytes, uploads every proof, and advertises one custom evidence-manifest item without changing what Incus downloads. See the action guide for a complete attestation and publication workflow.

The moving v0 tag follows public compatible v0.x.y releases. An exact tag such as v0.2.0 selects that repository and CLI release together. For the strongest supply-chain guarantee, pin the full release commit SHA and retain the exact version in a comment. The moving tag becomes available with the first public action-capable repository release. See the action reference for every input, output, and supported runner.

Security boundary

The S3 bucket must remain private, and the configured prefix must be dedicated to one mirror. The proxy does not authenticate downstream clients and does not terminate public TLS: deploy it behind an ingress or network boundary that provides HTTPS and the required access-control policy. See Deploy the proxy for the complete bucket, IAM, ingress, KMS, and multipart-cleanup requirements.

Configuration

Configuration precedence is fixed, highest first:

1. command flags;
2. SIMPLESTREAMS_S3_* environment variables;
3. the YAML file explicitly selected by --config or SIMPLESTREAMS_S3_CONFIG;
4. defaults.

There is no implicit config-file search. Unknown YAML keys and invalid values fail startup. Every setting is listed in the configuration reference.

Documentation

The documentation site covers publishing, deployment, the complete configuration and proxy interface references, and the design of the mirror.

Development

mise provisions the locked toolchain and Moon is the task front door:

mise install
moon run root:check
moon run root:integration

CI additionally runs the race detector and a real Incus listing/import acceptance gate. See CONTRIBUTING.md for the contribution workflow and SECURITY.md for private vulnerability reporting.

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE)
• MIT license (LICENSE-MIT)

at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.