git.stella-ops.org/docs/modules/scanner/design/surface-secrets.md

Surface.Secrets Design (Epic: SURFACE-SHARING)

Status: Draft v1.0 — aligns with tasks SURFACE-SECRETS-01..06, SCANNER-SECRETS-01..03, ZASTAVA-SECRETS-01..02, OPS-SECRETS-01..02.

Audience: Scanner/Zastava engineers, Security Guild, DevOps/Ops teams.

1. Goals

Surface.Secrets standardises how Scanner, Zastava, Scheduler, and related services obtain credentials and sensitive material required for surface operations (registry pull secrets, CAS tokens, manifest signing keys). Key requirements:

• Consistent, pluggable providers (Kubernetes Secret, file, inline, future vaults).
• Deterministic lookup keyed by tenant/component to avoid accidental leakage.
• Integration with Surface.Env & Surface.Validation for configuration and pre-flight checks.
• Minimal in-memory exposure; secrets wrapped in secure handles with automatic disposal.

2. Secret Types

Secret Type	Description	Example Consumers
cas-access	Credentials for RustFS/S3 object storage (access key/secret, session token).	Scanner Worker/WebService, Zastava Observer/Webhook
registry	Container registry auth (username/password or token).	Scanner Worker (pulling layers for SBOM)
attestation	DSSE signing key material, Rekor API tokens.	Scanner WebService (delegation), Attestor (future integration)
tls	Client TLS certificates for Surface.FS or other services.	Scanner Worker, Zastava Observer

Additional secret types can be registered via ISurfaceSecretTypeRegistry.

3. Provider Model

public interface ISurfaceSecretProvider
{
    ValueTask<SurfaceSecretHandle> GetAsync(SurfaceSecretRequest request, CancellationToken ct = default);
}

public sealed record SurfaceSecretRequest
(
    string Tenant,
    string Component, // e.g. "Scanner.Worker"
    string SecretType, // e.g. "cas-access"
    string? Name // optional override (e.g., "primary", "mirror-eu")
);

3.1 Built-in providers

1. Kubernetes – Reads from Secret objects. Configuration:
   • namespace: derived from SCANNER_SURFACE_SECRETS_ROOT or component override.
   • Secret name format: surface-{tenant}-{component}-{secretType}.
   • Supports key mapping (e.g., accessKey, secretKey, sessionToken).
2. File – Loads JSON/YAML files from a directory (for offline kit, dev). File path derived from root + tenant/component.
3. Inline – Accepts base64 encoded JSON from env (useful for tests).

3.2 Secret Handle

SurfaceSecretHandle exposes typed accessors (AsCredentials(), AsTlsCertificate()) and ensures sensitive data is cleared when disposed.

4. Configuration

Surface.Env supplies provider configuration (SecretsProviderConfiguration). Example:

{
  "provider": "kubernetes",
  "namespace": "stellaops-runtime",
  "prefix": "surface-",
  "fallbackProvider": "file",
  "file": {
    "root": "/etc/stellaops/secrets"
  }
}

Fallback provider allows offline development (use file provider if K8s secret missing).

5. Validation

Surface.Validation supplies validators:

• SecretProviderValidator – ensures provider ID is known; checks required configuration (namespace/root).
• SecretExistenceValidator – optional check verifying required secret types exist at startup (configurable list).
• SecretRotationValidator – warns when secrets are older than rotation window (uses metadata stored in provider).

Failures produce error codes (SURFACE_SECRET_PROVIDER_UNKNOWN, SURFACE_SECRET_MISSING, SURFACE_SECRET_STALE).

6. Security Considerations

• Secrets returned as SecureString/byte arrays; never log values.
• Kubernetes provider caches secrets in-memory with TTL (default 10 minutes) to reduce API calls; cache invalidated when generation changes.
• File provider enforces permissions (0600); rejects world-readable files.
• Inline provider meant for tests only; flag Surface:Secrets:AllowInline enables it explicitly.

7. Offline & Air-Gap Support

• Offline kits include offline/secrets/ with encrypted archive plus manifest file enumerating secret metadata (tenant, component, type, checksum).
• Import script decrypts archive using site-specific key and populates file provider root.
• Documented workflow lives in ops/offline-kit/TASKS.md and associated runbooks.

8. Observability

• Metrics: surface_secrets_requests_total{provider,result}.
• Logs: only log secret identifiers, never values.
• Traces: surface.secrets.get span showing provider latency.

9. Testing Strategy

• Unit tests per provider with fake backends.
• Integration tests in Scanner/Zastava verifying provider selection, fallback, and rotation.
• Security tests ensuring secrets aren’t leaked in logs or exceptions.

10. Future Enhancements

• Support for HashiCorp Vault / AWS Secrets Manager providers.
• Built-in DSSE signing key management for Attestor/Signer.
• Automatic rotation notifications via Notifier.

11. References

• docs/modules/scanner/design/surface-env.md
• docs/modules/scanner/design/surface-fs.md
• docs/modules/scanner/design/surface-validation.md
• docs/modules/airgap/airgap-mode.md