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yufan-su
57234a866a
Add an example gRPC credential-provider plugin which reads from k8s
secrets for the egress
credential-injection path.
- It resolves `ate-secret://k8s.io/default/<namespace>/<secret>/<key>`
URIs to Kubernetes Secret values, so Substrate never stores secrets — it
only
brokers a read that the provider is authorized to perform.
- It is the only
component in the injection path with Kubernetes secerts access; the
egress gateway and
its injector never read Secrets directly.
### What's included
- **`cmd/credential-provider/kubernetes-secrets`** — the gRPC service:
- Parses and validates `ate-secret://` URIs, resolving the requested
Secret
(with single-key fallback when the URI omits a key).
- Enforces an **atespace→namespace authorization policy**
(default-deny),
derived from the caller's attested actor SPIFFE ID.
- Serves over **mutual TLS**, requiring the caller's client cert to
chain to
the trust bundle *and* carry the egress injector's SPIFFE SAN.
- **Manifests** (`manifests/egress-credential-injection/`) — Deployment,
Service, ServiceAccount + RBAC, a sample namespace-policy ConfigMap, and
a
sample Secret.
- Renames the default provider address/service from `credprovider` to
`k8s-credential-provider` across `ate-setup`, install scripts, and the
egress
injection overlay.
### atespace → namespace authorization
Beyond the mTLS check that only the egress injector may call the
provider, each
request is authorized against a **default-deny atespace→namespace
policy**. The
provider derives the requesting actor's atespace from its attested
SPIFFE ID and
resolves a Secret only if that atespace is explicitly granted access to
the URI's
namespace.