# JWT Authentication for Poimen Memory Service

## Overview

Memory service validates incoming requests using JWT tokens issued by Authentik OIDC provider. The API Gateway (homelab-frontend) fetches a token from Authentik and passes it to Memory service as a bearer token. Memory service validates the token directly against Authentik's JWKS endpoint without requiring Vault in the request path.

## Architecture

```
Client/Gateway
    ↓ (Authorization: Bearer <JWT>)
Memory Service (http_server)
    ↓ validate_jwt_token()
Authentik JWKS Endpoint (cached)
    ↓ (signature + claims validation)
JwtClaims (sub, iss, aud, permissions, groups)
    ↓ (check has_capability())
Route Handler (ingest, query, vault, etc.)
```

## Configuration

### Environment Variables

Required for JWT mode:
- `MEM_AUTH_MODE=jwt` — Enable JWT validation (default: apikey)
- `AUTHENTIK_ISSUER` — Authentik OIDC issuer, e.g. `https://authentik.riotpiao.com/application/o/memory/`
- `AUTHENTIK_AUDIENCE` — Memory service's client ID in Authentik, e.g. `poimen-memory`

Optional:
- `JWT_CACHE_TTL_SECS` — JWKS cache TTL in seconds (default: 3600)

### K8s Deployment

```yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: poimen-memory
  namespace: poimen
spec:
  template:
    spec:
      containers:
      - name: memory
        image: registry/poimen-memory:latest
        env:
        - name: MEM_AUTH_MODE
          value: "jwt"
        - name: AUTHENTIK_ISSUER
          valueFrom:
            configMapKeyRef:
              name: poimen-config
              key: authentik-issuer-url
        - name: AUTHENTIK_AUDIENCE
          valueFrom:
            configMapKeyRef:
              name: poimen-config
              key: memory-client-id
        - name: JWT_CACHE_TTL_SECS
          value: "3600"
        # ... other env vars
```

## Capabilities

JWT tokens must include a `permissions` claim with one of:
- `memory:read` — Read-only: query, skills, projects, vault browsing
- `memory:write` — Write: ingest, source sync, vault generation
- `*` — Wildcard: all capabilities (typically for homelab-admins group)

Example permissions claim in token:
```json
{
  "permissions": ["memory:read", "memory:write"]
}
```

## API Request Format

```bash
# Fetch JWT from Authentik (typically done by API Gateway)
TOKEN=$(curl -s -X POST https://authentik.riotpiao.com/application/o/token/ \
  -d "grant_type=client_credentials&client_id=...&client_secret=...")

# Call Memory API with bearer token
curl -H "Authorization: Bearer ${TOKEN}" \
  http://poimen-memory/memory/query?project=myproject&query=topic
```

## Security Considerations

1. **Algorithm Pinning**: Only RS256 accepted (defense against algorithm confusion attacks)
2. **Signature Validation**: All tokens verified against Authentik's public keys
3. **Claim Pinning**: `iss` (issuer) and `aud` (audience) must match configured values
4. **Expiry Check**: Expired tokens rejected (60s clock skew tolerance)
5. **JWKS Caching**: Keys cached with TTL; refreshed on key ID miss (handles rotation)
6. **Token TTL**: Memory service does not cache validation results; each request re-validates

## Backward Compatibility

Default `MEM_AUTH_MODE=apikey` preserves old behavior:
- Checks `apikey` header against `MEM_API_KEY` env var
- Grants synthetic `*` permission
- Useful for local dev/test

Switch to JWT by setting `MEM_AUTH_MODE=jwt`.

## Capability Checking in Handlers

Each handler checks for required capability:

```rust
// In ingest_handler (write operation)
if !has_capability(&claims, "memory:write") {
    return HttpResponse::Forbidden().json(...);
}

// In query_handler (read operation)
if !has_capability(&claims, "memory:read") {
    return HttpResponse::Forbidden().json(...);
}
```

Wildcard permission `*` grants all.

## Testing

Unit tests in `tests/it_jwt_auth.rs`:
- Bearer token extraction
- JWT claims structures
- Permission validation
- Wildcard permission handling

```bash
cargo test --test it_jwt_auth
```

Example test:
```rust
#[test]
fn test_jwt_permissions_claim() {
    let claims = JwtClaims {
        permissions: Some(vec!["memory:read".to_string()]),
        ...
    };
    assert!(claims.permissions.unwrap().contains(&"memory:read".to_string()));
}
```

## Troubleshooting

### "Invalid Authorization header format"
- Ensure request includes `Authorization: Bearer <token>` (capital B)
- Token must not be empty

### "JWT validation failed: Token validation failed"
- Check token signature: ensure Authentik JWKS endpoint is reachable
- Verify issuer matches `AUTHENTIK_ISSUER` env var
- Verify audience matches `AUTHENTIK_AUDIENCE` env var

### "Missing capability: memory:write"
- Token's `permissions` claim must include `memory:write` or `*`
- Check Authentik app scope configuration includes `permissions` claim

### JWKS fetch timeout
- Ensure Authentik is reachable from Memory pod
- Check network policies / firewall rules
- Verify `AUTHENTIK_ISSUER` URL is correct

## Related Files

- `crates/mem-cli/src/jwt_validator.rs` — Token validation logic
- `crates/mem-cli/src/http_server.rs` — Handler integration
- `tests/it_jwt_auth.rs` — Integration tests
- `/Users/rockliang/workplace/homelab/project-usage/jwt-auth-rollout.md` — Cluster-wide OIDC setup