Janus is an experimental implementation of the Distributed Aggregation Protocol (DAP) specification. Currently it supports VDAFs with trivial aggregation parameters only, e.g. Prio3. VDAFs with nontrivial aggregation parameters (e.g. Poplar1) are not yet supported.
Janus is currently in active development.
The main branch is under continuous development and will usually be partway
between DAP drafts. Janus uses stable release branches to maintain
implementations of different DAP draft versions. Rust crates and container
images with versions x.y.z are released from a corresponding release/x.y
branch.
| Git branch | Draft version | Conforms to protocol? | Status |
|---|---|---|---|
release/0.1 |
draft-ietf-ppm-dap-01 |
Yes | Unmaintained as of December 7, 2022 |
release/0.2 |
draft-ietf-ppm-dap-02 |
Yes | Unmaintained as of July 13, 2023 |
release/0.3 |
draft-ietf-ppm-dap-03 |
Yes | Unmaintained as of February 6, 2023 |
release/0.4 |
draft-ietf-ppm-dap-04 |
Yes | Unmaintained as of May 24, 2023 |
release/0.subscriber-01 |
draft-ietf-ppm-dap-02 plus extensions |
No | Unmaintained as of November 1, 2023 |
release/0.5 |
draft-ietf-ppm-dap-04 |
Yes | Supported |
release/0.6 |
draft-ietf-ppm-dap-07 |
Yes, with errata | Supported |
main |
draft-ietf-ppm-dap-09 |
Partially | Supported |
Note that no version of Janus supports draft-ietf-ppm-dap-05 or -06. Draft
05 was skipped because there were flaws in its usage of the new ping-pong
topology introduced in draft-irtf-cfrg-vdaf-06. Draft 6 fixed those issues,
but was skipped because it was published from the wrong commit of
draft-ietf-ppm-dap and so contains a couple of bugs.
draft-ietf-ppm-dap-07 is effectively identical to draft 6, but with those bugs
fixed.
draft-ietf-ppm-dap-08 was also skipped, since it contained only minor
mechanical protocol changes and was not implemented or deployed by anyone else.
There is a bug in Janus' release/0.6 branch wherein PrepareResp messages are
incorrectly encoded, making Janus incompatible with other DAP Aggregator
implementations.
See issue #2466 for details.
Janus follows semantic versioning. Because we are at major version 0, we increment the minor version number for breaking changes, and increment the patch version for new features and backwards-compatible bug fixes.
What is considered a breaking change depends on the crate. The following crates are stable on their Rust API:
janus_collectorjanus_clientjanus_messages
janus_core is published to crates.io, but has no stability guarantees. It
should not be depended on directly. If you find yourself needing to depend
on it directly while using any other Janus crates, open a bug report.
The following crates are stable on their external configuration, CLI arguments, and HTTP API. Their Rust API may arbitrarily change and should not be depended on. They are not published to crates.io.
janus_aggregatorjanus_tools
Any other crates not mentioned have no stability guarantees whatsoever.
docker must be installed at build time, and the
docker daemon must be running. To build Janus, execute cargo build.
Note that podman is not an acceptable substitute for docker. There are
subtle incompatibilities between the two that will cause tests to fail.
To build container images, run docker buildx bake --load. This will produce
images tagged janus_aggregator, janus_aggregation_job_creator,
janus_aggregation_job_driver, janus_collection_job_driver, janus_cli,
janus_db_migrator, janus_interop_client, janus_interop_aggregator, and
janus_interop_collector by default.
Pre-built container images are available at us-west2-docker.pkg.dev/divviup-artifacts-public/janus.
We support the latest stable version of Rust, at time of release, and the two preceding minor versions.
Tests require that docker and
kind be installed on the machine running the tests
and in the PATH of the test-runner's environment. The docker daemon must be
running. CI tests currently use kind 0.20.0 and the
corresponding Kubernetes 1.26 node image
(kindest/node:v1.26.6@sha256:6e2d8b28a5b601defe327b98bd1c2d1930b49e5d8c512e1895099e4504007adb).
Using the same versions for local development is recommended.
To run Janus tests, execute cargo test. To run tests on Docker images, execute
cargo xtask test-docker.
If you experience issues with tests using Kind on Linux, you may need to adjust inotify sysctls. Both systemd and Kubernetes inside each Kind node make use of inotify. When combined with other services and desktop applications, they may exhaust per-user limits.
See the documentation on deploying Janus for details about its configuration and operation.
janus_core has the following features available.
database: Enables implementations ofpostgres_types::ToSqlandpostgres_types::FromSqlonjanus_core::Interval.test-util: Enables miscellaneous test-only APIs. This should not be used outside of tests, and any such APIs do not carry any stability guarantees.
janus_aggregator has the following features available.
otlp: Enables OTLP exporter support for both metrics and tracing. See the metrics and tracing documentation for configuration instructions.prometheus: Enables a Prometheus metrics exporter; see the documentation for configuration instructions.test-util: Enables miscellaneous test-only APIs. This should not be used outside of tests, and any such APIs do not carry any stability guarantees.tokio-console: Enables a tracing subscriber and server to supporttokio-console. See the documentation for configuration instructions.