git.stella-ops.org/docs/ARCHITECTURE_CONCELIER.md

component_architecture_concelier.md — Stella Ops Concelier (2025Q4)

Scope. Implementation‑ready architecture for Concelier: the vulnerability ingest/normalize/merge/export subsystem that produces deterministic advisory data for the Scanner + Policy + Excititor pipeline. Covers domain model, connectors, merge rules, storage schema, exports, APIs, performance, security, and test matrices.

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0) Mission & boundaries

Mission. Acquire authoritative vulnerability advisories (vendor PSIRTs, distros, OSS ecosystems, CERTs), normalize them into a canonical model, reconcile aliases and version ranges, and export deterministic artifacts (JSON, Trivy DB) for fast backend joins.

Boundaries.

• Concelier does not sign with private keys. When attestation is required, the export artifact is handed to the Signer/Attestor pipeline (out‑of‑process).
• Concelier does not decide PASS/FAIL; it provides data to the Policy engine.
• Online operation is allowlist‑only; air‑gapped deployments use the Offline Kit.

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1) Topology & processes

Process shape: single ASP.NET Core service StellaOps.Concelier.WebService hosting:

• Scheduler with distributed locks (Mongo backed).
• Connectors (fetch/parse/map).
• Merger (canonical record assembly + precedence).
• Exporters (JSON, Trivy DB).
• Minimal REST for health/status/trigger/export.

Scale: HA by running N replicas; locks prevent overlapping jobs per source/exporter.

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2) Canonical domain model

Stored in MongoDB (database concelier), serialized with a canonical JSON writer (stable order, camelCase, normalized timestamps).

2.1 Core entities

Advisory

advisoryId          // internal GUID
advisoryKey         // stable string key (e.g., CVE-2025-12345 or vendor ID)
title               // short title (best-of from sources)
summary             // normalized summary (English; i18n optional)
published           // earliest source timestamp
modified            // latest source timestamp
severity            // normalized {none, low, medium, high, critical}
cvss                // {v2?, v3?, v4?} objects (vector, baseScore, severity, source)
exploitKnown        // bool (e.g., KEV/active exploitation flags)
references[]        // typed links (advisory, kb, patch, vendor, exploit, blog)
sources[]           // provenance for traceability (doc digests, URIs)

Alias

advisoryId
scheme              // CVE, GHSA, RHSA, DSA, USN, MSRC, etc.
value               // e.g., "CVE-2025-12345"

Affected

advisoryId
productKey          // canonical product identity (see 2.2)
rangeKind           // semver | evr | nvra | apk | rpm | deb | generic | exact
introduced?         // string (format depends on rangeKind)
fixed?              // string (format depends on rangeKind)
lastKnownSafe?      // optional explicit safe floor
arch?               // arch or platform qualifier if source declares (x86_64, aarch64)
distro?             // distro qualifier when applicable (rhel:9, debian:12, alpine:3.19)
ecosystem?          // npm|pypi|maven|nuget|golang|…
notes?              // normalized notes per source

Reference

advisoryId
url
kind                // advisory | patch | kb | exploit | mitigation | blog | cvrf | csaf
sourceTag           // e.g., vendor/redhat, distro/debian, oss/ghsa

MergeEvent

advisoryKey
beforeHash          // canonical JSON hash before merge
afterHash           // canonical JSON hash after merge
mergedAt
inputs[]            // source doc digests that contributed

AdvisoryStatement (event log)

statementId         // GUID (immutable)
vulnerabilityKey    // canonical advisory key (e.g., CVE-2025-12345)
advisoryKey         // merge snapshot advisory key (may reference variant)
statementHash       // canonical hash of advisory payload
asOf                // timestamp of snapshot (UTC)
recordedAt          // persistence timestamp (UTC)
inputDocuments[]    // document IDs contributing to the snapshot
payload             // canonical advisory document (BSON / canonical JSON)

AdvisoryConflict

conflictId          // GUID
vulnerabilityKey    // canonical advisory key
conflictHash        // deterministic hash of conflict payload
asOf                // timestamp aligned with originating statement set
recordedAt          // persistence timestamp
statementIds[]      // related advisoryStatement identifiers
details             // structured conflict explanation / merge reasoning

• AdvisoryEventLog (Concelier.Core) provides the public API for appending immutable statements/conflicts and querying replay history. Inputs are normalized by trimming and lower-casing vulnerabilityKey, serializing advisories with CanonicalJsonSerializer, and computing SHA-256 hashes (statementHash, conflictHash) over the canonical JSON payloads. Consumers can replay by key with an optional asOf filter to obtain deterministic snapshots ordered by asOf then recordedAt.
• Conflict explainers are serialized as deterministic MergeConflictExplainerPayload records (type, reason, source ranks, winning values); replay clients can parse the payload to render human-readable rationales without re-computing precedence.
• Concelier.WebService exposes the immutable log via GET /concelier/advisories/{vulnerabilityKey}/replay[?asOf=UTC_ISO8601], returning the latest statements (with hex-encoded hashes) and any conflict explanations for downstream exporters and APIs.

ExportState

exportKind          // json | trivydb
baseExportId?       // last full baseline
baseDigest?         // digest of last full baseline
lastFullDigest?     // digest of last full export
lastDeltaDigest?    // digest of last delta export
cursor              // per-kind incremental cursor
files[]             // last manifest snapshot (path → sha256)

2.2 Product identity (productKey)

• Primary: purl (Package URL).
• OS packages: RPM (NEVRA→purl:rpm), DEB (dpkg→purl:deb), APK (apk→purl:alpine), with EVR/NVRA preserved.
• Secondary: cpe retained for compatibility; advisory records may carry both.
• Image/platform: oci:<registry>/<repo>@<digest> for image‑level advisories (rare).
• Unmappable: if a source is non‑deterministic, keep native string under productKey="native:<provider>:<id>" and mark non‑joinable.

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3) Source families & precedence

3.1 Families

• Vendor PSIRTs: Microsoft, Oracle, Cisco, Adobe, Apple, VMware, Chromium…
• Linux distros: Red Hat, SUSE, Ubuntu, Debian, Alpine…
• OSS ecosystems: OSV, GHSA (GitHub Security Advisories), PyPI, npm, Maven, NuGet, Go.
• CERTs / national CSIRTs: CISA (KEV, ICS), JVN, ACSC, CCCS, KISA, CERT‑FR/BUND, etc.

3.2 Precedence (when claims conflict)

1. Vendor PSIRT (authoritative for their product).
2. Distro (authoritative for packages they ship, including backports).
3. Ecosystem (OSV/GHSA) for library semantics.
4. CERTs/aggregators for enrichment (KEV/known exploited).

Precedence affects Affected ranges and fixed info; severity is normalized to the maximum credible severity unless policy overrides. Conflicts are retained with source provenance.

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4) Connectors & normalization

4.1 Connector contract

public interface IFeedConnector {
  string SourceName { get; }
  Task FetchAsync(IServiceProvider sp, CancellationToken ct);   // -> document collection
  Task ParseAsync(IServiceProvider sp, CancellationToken ct);   // -> dto collection (validated)
  Task MapAsync(IServiceProvider sp, CancellationToken ct);     // -> advisory/alias/affected/reference
}

• Fetch: windowed (cursor), conditional GET (ETag/Last‑Modified), retry/backoff, rate limiting.
• Parse: schema validation (JSON Schema, XSD/CSAF), content type checks; write DTO with normalized casing.
• Map: build canonical records; all outputs carry provenance (doc digest, URI, anchors).

4.2 Version range normalization

• SemVer ecosystems (npm, pypi, maven, nuget, golang): normalize to introduced/fixed semver ranges (use ~, ^, <, >= canonicalized to intervals).
• RPM EVR: epoch:version-release with rpmvercmp semantics; store raw EVR strings and also computed order keys for query.
• DEB: dpkg version comparison semantics mirrored; store computed keys.
• APK: Alpine version semantics; compute order keys.
• Generic: if provider uses text, retain raw; do not invent ranges.

4.3 Severity & CVSS

• Normalize CVSS v2/v3/v4 where available (vector, baseScore, severity).
• If multiple CVSS sources exist, track them all; effective severity defaults to max by policy (configurable).
• ExploitKnown toggled by KEV and equivalent sources; store evidence (source, date).

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5) Merge engine

5.1 Keying & identity

• Identity graph: CVE is primary node; vendor/distro IDs resolved via Alias edges (from connectors and Concelier’s alias tables).
• advisoryKey is the canonical primary key (CVE if present, else vendor/distro key).

5.2 Merge algorithm (deterministic)

1. Gather all rows for advisoryKey (across sources).

2. Select title/summary by precedence source (vendor>distro>ecosystem>cert).

3. Union aliases (dedupe by scheme+value).

4. Merge Affected with rules:

   • Prefer vendor ranges for vendor products; prefer distro for distro‑shipped packages.
   • If both exist for same productKey, keep both; mark sourceTag and precedence so Policy can decide.
   • Never collapse range semantics across different families (e.g., rpm EVR vs semver).

5. CVSS/severity: record all CVSS sets; compute effectiveSeverity = max (unless policy override).

6. References: union with type precedence (advisory > patch > kb > exploit > blog); dedupe by URL; preserve sourceTag.

7. Produce canonical JSON; compute afterHash; store MergeEvent with inputs and hashes.

The merge is pure given inputs. Any change in inputs or precedence matrices changes the hash predictably.

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6) Storage schema (MongoDB)

Collections & indexes

• source {_id, type, baseUrl, enabled, notes}

• source_state {sourceName(unique), enabled, cursor, lastSuccess, backoffUntil, paceOverrides}

• document {_id, sourceName, uri, fetchedAt, sha256, contentType, status, metadata, gridFsId?, etag?, lastModified?}

  • Index: {sourceName:1, uri:1} unique, {fetchedAt:-1}

• dto {_id, sourceName, documentId, schemaVer, payload, validatedAt}

  • Index: {sourceName:1, documentId:1}

• advisory {_id, advisoryKey, title, summary, published, modified, severity, cvss, exploitKnown, sources[]}

  • Index: {advisoryKey:1} unique, {modified:-1}, {severity:1}, text index (title, summary)

• alias {advisoryId, scheme, value}

  • Index: {scheme:1,value:1}, {advisoryId:1}

• affected {advisoryId, productKey, rangeKind, introduced?, fixed?, arch?, distro?, ecosystem?}

  • Index: {productKey:1}, {advisoryId:1}, {productKey:1, rangeKind:1}

• reference {advisoryId, url, kind, sourceTag}

  • Index: {advisoryId:1}, {kind:1}

• merge_event {advisoryKey, beforeHash, afterHash, mergedAt, inputs[]}

  • Index: {advisoryKey:1, mergedAt:-1}

• export_state {_id(exportKind), baseExportId?, baseDigest?, lastFullDigest?, lastDeltaDigest?, cursor, files[]}

• locks {_id(jobKey), holder, acquiredAt, heartbeatAt, leaseMs, ttlAt} (TTL cleans dead locks)

• jobs {_id, type, args, state, startedAt, heartbeatAt, endedAt, error}

GridFS buckets: fs.documents for raw payloads.

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7) Exporters

7.1 Deterministic JSON (vuln‑list style)

• Folder structure mirroring /<scheme>/<first-two>/<rest>/… with one JSON per advisory; deterministic ordering, stable timestamps, normalized whitespace.
• manifest.json lists all files with SHA‑256 and a top‑level export digest.

7.2 Trivy DB exporter

• Builds Bolt DB archives compatible with Trivy; supports full and delta modes.

• In delta, unchanged blobs are reused from the base; metadata captures:

  {
    "mode": "delta|full",
    "baseExportId": "...",
    "baseManifestDigest": "sha256:...",
    "changed": ["path1", "path2"],
    "removed": ["path3"]
  }
  

• Optional ORAS push (OCI layout) for registries.

• Offline kit bundles include Trivy DB + JSON tree + export manifest.

• Mirror-ready bundles: when concelier.trivy.mirror defines domains, the exporter emits mirror/index.json plus per-domain manifest.json, metadata.json, and db.tar.gz files with SHA-256 digests so Concelier mirrors can expose domain-scoped download endpoints.

• Concelier.WebService serves /concelier/exports/index.json and /concelier/exports/mirror/{domain}/… directly from the export tree with hour-long budgets (index: 60 s, bundles: 300 s, immutable) and per-domain rate limiting; the endpoints honour Stella Ops Authority or CIDR bypass lists depending on mirror topology.

7.3 Hand‑off to Signer/Attestor (optional)

• On export completion, if attest: true is set in job args, Concelier posts the artifact metadata to Signer/Attestor; Concelier itself does not hold signing keys.
• Export record stores returned { uuid, index, url } from Rekor v2.

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8) REST APIs

All under /api/v1/concelier.

Health & status

GET  /healthz | /readyz
GET  /status                              → sources, last runs, export cursors

Sources & jobs

GET  /sources                              → list of configured sources
POST /sources/{name}/trigger               → { jobId }
POST /sources/{name}/pause | /resume       → toggle
GET  /jobs/{id}                            → job status

Exports

POST /exports/json   { full?:bool, force?:bool, attest?:bool } → { exportId, digest, rekor? }
POST /exports/trivy  { full?:bool, force?:bool, publish?:bool, attest?:bool } → { exportId, digest, rekor? }
GET  /exports/{id}   → export metadata (kind, digest, createdAt, rekor?)
GET  /concelier/exports/index.json        → mirror index describing available domains/bundles
GET  /concelier/exports/mirror/{domain}/manifest.json
GET  /concelier/exports/mirror/{domain}/bundle.json
GET  /concelier/exports/mirror/{domain}/bundle.json.jws

Search (operator debugging)

GET  /advisories/{key}
GET  /advisories?scheme=CVE&value=CVE-2025-12345
GET  /affected?productKey=pkg:rpm/openssl&limit=100

AuthN/Z: Authority tokens (OpTok) with roles: concelier.read, concelier.admin, concelier.export.

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9) Configuration (YAML)

concelier:
  mongo: { uri: "mongodb://mongo/concelier" }
  s3:
    endpoint: "http://minio:9000"
    bucket: "stellaops-concelier"
  scheduler:
    windowSeconds: 30
    maxParallelSources: 4
  sources:
    - name: redhat
      kind: csaf
      baseUrl: https://access.redhat.com/security/data/csaf/v2/
      signature: { type: pgp, keys: [ "…redhat PGP…" ] }
      enabled: true
      windowDays: 7
    - name: suse
      kind: csaf
      baseUrl: https://ftp.suse.com/pub/projects/security/csaf/
      signature: { type: pgp, keys: [ "…suse PGP…" ] }
    - name: ubuntu
      kind: usn-json
      baseUrl: https://ubuntu.com/security/notices.json
      signature: { type: none }
    - name: osv
      kind: osv
      baseUrl: https://api.osv.dev/v1/
      signature: { type: none }
    - name: ghsa
      kind: ghsa
      baseUrl: https://api.github.com/graphql
      auth: { tokenRef: "env:GITHUB_TOKEN" }
  exporters:
    json:
      enabled: true
      output: s3://stellaops-concelier/json/
    trivy:
      enabled: true
      mode: full
      output: s3://stellaops-concelier/trivy/
      oras:
        enabled: false
        repo: ghcr.io/org/concelier
  precedence:
    vendorWinsOverDistro: true
    distroWinsOverOsv: true
  severity:
    policy: max    # or 'vendorPreferred' / 'distroPreferred'

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10) Security & compliance

• Outbound allowlist per connector (domains, protocols); proxy support; TLS pinning where possible.
• Signature verification for raw docs (PGP/cosign/x509) with results stored in document.metadata.sig. Docs failing verification may still be ingested but flagged; merge can down‑weight or ignore them by config.
• No secrets in logs; auth material via env: or mounted files; HTTP redaction of Authorization headers.
• Multi‑tenant: per‑tenant DBs or prefixes; per‑tenant S3 prefixes; tenant‑scoped API tokens.
• Determinism: canonical JSON writer; export digests stable across runs given same inputs.

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11) Performance targets & scale

• Ingest: ≥ 5k documents/min on 4 cores (CSAF/OpenVEX/JSON).
• Normalize/map: ≥ 50k Affected rows/min on 4 cores.
• Merge: ≤ 10 ms P95 per advisory at steady‑state updates.
• Export: 1M advisories JSON in ≤ 90 s (streamed, zstd), Trivy DB in ≤ 60 s on 8 cores.
• Memory: hard cap per job; chunked streaming writers; backpressure to avoid GC spikes.

Scale pattern: add Concelier replicas; Mongo scaling via indices and read/write concerns; GridFS only for oversized docs.

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12) Observability

• Metrics

  • concelier.fetch.docs_total{source}
  • concelier.fetch.bytes_total{source}
  • concelier.parse.failures_total{source}
  • concelier.map.affected_total{source}
  • concelier.merge.changed_total
  • concelier.export.bytes{kind}
  • concelier.export.duration_seconds{kind}

• Tracing around fetch/parse/map/merge/export.

• Logs: structured with source, uri, docDigest, advisoryKey, exportId.

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13) Testing matrix

• Connectors: fixture suites for each provider/format (happy path; malformed; signature fail).
• Version semantics: EVR vs dpkg vs semver edge cases (epoch bumps, tilde versions, pre‑releases).
• Merge: conflicting sources (vendor vs distro vs OSV); verify precedence & dual retention.
• Export determinism: byte‑for‑byte stable outputs across runs; digest equality.
• Performance: soak tests with 1M advisories; cap memory; verify backpressure.
• API: pagination, filters, RBAC, error envelopes (RFC 7807).
• Offline kit: bundle build & import correctness.

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14) Failure modes & recovery

• Source outages: scheduler backs off with exponential delay; source_state.backoffUntil; alerts on staleness.
• Schema drifts: parse stage marks DTO invalid; job fails with clear diagnostics; connector version flags track supported schema ranges.
• Partial exports: exporters write to temp prefix; manifest commit is atomic; only then move to final prefix and update export_state.
• Resume: all stages idempotent; source_state.cursor supports window resume.

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15) Operator runbook (quick)

• Trigger all sources: POST /api/v1/concelier/sources/*/trigger
• Force full export JSON: POST /api/v1/concelier/exports/json { "full": true, "force": true }
• Force Trivy DB delta publish: POST /api/v1/concelier/exports/trivy { "full": false, "publish": true }
• Inspect advisory: GET /api/v1/concelier/advisories?scheme=CVE&value=CVE-2025-12345
• Pause noisy source: POST /api/v1/concelier/sources/osv/pause

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16) Rollout plan

1. MVP: Red Hat (CSAF), SUSE (CSAF), Ubuntu (USN JSON), OSV; JSON export.
2. Add: GHSA GraphQL, Debian (DSA HTML/JSON), Alpine secdb; Trivy DB export.
3. Attestation hand‑off: integrate with Signer/Attestor (optional).
4. Scale & diagnostics: provider dashboards, staleness alerts, export cache reuse.
5. Offline kit: end‑to‑end verified bundles for air‑gap.