d-OAuth-Server

d-OAuth

An OAuth 2.1-only authorization server written in Rust. It is deliberately not backwards compatible with OAuth 2.0: PKCE is mandatory, the implicit and resource-owner-password grants do not exist, bearer-in-query is rejected, and redirect URIs match exactly.

It implements the authorization-code, refresh-token, client-credentials, device-code, and token-exchange grants, with DPoP, mTLS, PAR, JAR, dynamic client registration, introspection, and revocation. Tokens are opaque and hashed at rest. All durable domain state is in PostgreSQL and all ephemeral state is in Redis, so replicas are interchangeable.

• Protocol and deltas: docs/OAUTH.md
• Threat model and token design: docs/SECURITY.md
• Module layout and request flow: docs/ARCHITECTURE.md
• Every configuration key: docs/CONFIGURATION.md
• Schema and migrations: docs/DATABASE.md
• Redis keys and durability: docs/REDIS.md
• Container and cluster: docs/DEPLOYMENT.md
• Admin CLI and runbooks: docs/OPERATIONS.md
• Contributor guide: docs/CONTRIBUTING.md
• Changelog: docs/CHANGELOG.md
• Admin bootstrap procedure: RUNBOOK.md

Prerequisites

• Rust stable, as pinned by rust-toolchain.toml.
• PostgreSQL 14 or newer with the citext extension available.
• Redis 7.2 or newer, with persistence enabled and eviction off.
• A TLS certificate and key for the public listener.
• Docker, for the container image and for the integration tests that use testcontainers.
• cargo-nextest for the test suite: cargo install cargo-nextest --locked.

Build

cargo build --locked
cargo build --locked --release

Quick start

The server reads configuration from D_OAUTH_* environment variables. Export a development configuration (values here are placeholders; see docs/CONFIGURATION.md for every key).

export D_OAUTH_ISSUER=https://localhost:8080
export D_OAUTH_ENVIRONMENT=development
export D_OAUTH_BIND_ADDR=0.0.0.0:8080
export D_OAUTH_HEALTH_ADDR=0.0.0.0:8081
export D_OAUTH_TLS__CERT_PATH=/path/to/tls.crt
export D_OAUTH_TLS__KEY_PATH=/path/to/tls.key
export D_OAUTH_DATABASE__URL='postgres://oauth:password@127.0.0.1:5432/oauth?sslmode=disable'
export D_OAUTH_REDIS__URL=redis://127.0.0.1:6379
export D_OAUTH_REDIS__DURABILITY=waitaof
export D_OAUTH_TOKEN_PEPPER='replace-with-32-bytes-of-random'
export D_OAUTH_TOTP_ENCRYPTION_KEY='replace-with-32-bytes-of-random'

Development relaxes the database TLS requirement. Production requires sslmode=verify-full and a non-localhost issuer.

Validate the configuration, then apply the schema once:

cargo run --bin d-oauth-server -- config check
cargo run --bin d-oauth-server -- migrate

Bootstrap the first administrator. It is created in a forced-change state and must change its password and enroll TOTP before it gains authority:

cargo run --bin d-oauth-server -- admin bootstrap --email admin@example.com

Apply the scope catalog, redirect URIs, and entitlements from a JSON file idempotently. The file format is in docs/OPERATIONS.md:

cargo run --bin d-oauth-server -- config sync --file ./oauth-config.json

Run the server. It serves TLS on bind_addr and plaintext health on health_addr; it never migrates:

cargo run --bin d-oauth-server -- serve

Check it is alive and ready:

curl -s http://127.0.0.1:8081/health/live
curl -s http://127.0.0.1:8081/health/ready
curl -sk https://localhost:8080/.well-known/oauth-authorization-server | jq .

Authorization-code and PKCE walkthrough

The flow is: start at /authorize, log in and consent, receive a code on the redirect, then redeem it at /token with the PKCE verifier.

1. Generate a verifier and its S256 challenge:

   VERIFIER=$(openssl rand -base64 64 | tr -d '=+/' | cut -c1-64)
   CHALLENGE=$(printf '%s' "$VERIFIER" | openssl dgst -sha256 -binary | openssl base64 -A | tr '+/' '-_' | tr -d '=')
   

2. Visit the authorization endpoint in a browser. A confidential client must use PAR or a signed request object; a public client may use the query string:

   https://localhost:8080/authorize?response_type=code&client_id=example-client&redirect_uri=https://app.example.com/callback&scope=orders:read&state=xyz&code_challenge=$CHALLENGE&code_challenge_method=S256
   

3. Log in, approve consent, and read the code from the redirect.

4. Redeem the code at the token endpoint:

   curl -sk https://localhost:8080/token \
   -d grant_type=authorization_code \
   -d code="$CODE" \
   -d redirect_uri=https://app.example.com/callback \
   -d client_id=example-client \
   -d code_verifier="$VERIFIER"
   

5. A public client must present a DPoP proof with the token request; a confidential client authenticates with its secret or an mTLS certificate.

The POST /token dispatcher and the /register* DCR routes (RFC 7591/RFC 7592) are wired, so step 4 redeems a code end to end; a client can also be created through POST /register. See docs/OAUTH.md for the full grant behavior.

Tests

The authoritative suite:

cargo nextest run --all-targets
cargo test --doc

The integration and end-to-end tests start real Postgres and Redis containers, so Docker must be running. To iterate on one area, filter by name:

cargo nextest run -E 'test(refresh_rotation)'
cargo nextest run -E 'test(admin_bootstrap)'

Quality gates:

cargo fmt --check
cargo clippy --all-targets -- -D warnings
cargo audit
cargo deny check
python3 scripts/check_doc_links.py

Container

Build both architectures with the bake definition, then run the image. The image is non-root, has no shell, and expects a read-only root filesystem:

# Both architectures (linux/amd64 + linux/arm64)
docker buildx bake image

# Single architecture (no arm64 QEMU emulation needed)
docker buildx bake image --set image.platform=linux/amd64

docker run --rm -p 8080:8080 --read-only \
  --env-file ./oauth.env \
  -v /path/to/tls:/certs:ro \
  d-oauth-server:latest

Building linux/arm64 on an amd64 host needs QEMU binfmt (docker run --privileged --rm tonistiigi/binfmt --install arm64); see docs/DEPLOYMENT.md.

The container HEALTHCHECK uses the healthcheck subcommand, which probes the plaintext health listener without a shell or curl. See docs/DEPLOYMENT.md.

For a local multi-replica proof, the deployment assets provide a compose file that runs three app replicas against one Postgres and one Redis. It is the local analogue of the cluster manifests, and proves that a token issued by one replica is introspectable via another. If your checkout does not include the compose file yet, it ships with the cluster manifests; see docs/DEPLOYMENT.md:

docker compose up --scale app=3

Cluster deployment uses a separate migration Job, a PodDisruptionBudget, and probes on the health listener. In-process mTLS requires L4/TCP passthrough at the load balancer, because an L7 ingress that terminates TLS strips the client certificate.

Security caveats

• OAuth 2.1 only. Do not point an OAuth 2.0 client that needs implicit or password grant at this server.
• The server targets draft-ietf-oauth-v2-1-16 (published 3 September 2026; an Internet-Draft, not an RFC): https://datatracker.ietf.org/doc/html/draft-ietf-oauth-v2-1. Known gaps against that draft are listed in docs/OAUTH.md.
• There is no default credential and no HTTP admin API. Provision through the CLI.
• The token pepper and TOTP encryption key are required; losing the pepper invalidates every live opaque token.
• Production requires issuer on https and a database URL with sslmode=verify-full.
• Redis must run with noeviction and persistence. The server asserts this at startup and refuses to start otherwise.
• When Postgres or Redis is unavailable, security endpoints return 503 rather than failing open.
• CORS is empty by default. Browser clients need an explicit origin allowlist.
• Never commit a secret, a token, or key material. See docs/SECURITY.md.

CLI pointers

• Scope catalog: scope create|list|enable|disable|delete. Scopes are runtime-managed and start empty.
• Redirect URIs: redirect-uri create|list|enable|disable|delete and client attach-redirect-uri|detach-redirect-uri|redirect-uris. Each accepts --kind authorize|post_logout (default authorize); post_logout URIs are the return targets for GET /logout.
• Users and entitlements: user create|enroll-totp|disable|grant-scope|revoke-scope|scopes.
• Admin: admin bootstrap (see RUNBOOK.md).
• Declarative apply: config sync --file and config check.
• DCR initial access: initial-access-token issue.
• Utilities: keygen and healthcheck.

Full flags are in docs/OPERATIONS.md.

License

MIT OR Apache-2.0. See LICENSE.md.