Rewrite architecture docs and add Vexer connector template
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docs/ARCHITECTURE_SCANNER.md
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# component_architecture_scanner.md — **Stella Ops Scanner** (2025Q4)
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> **Scope.** Implementation‑ready architecture for the **Scanner** subsystem: WebService, Workers, analyzers, SBOM assembly (inventory & usage), per‑layer caching, three‑way diffs, artifact catalog (MinIO+Mongo), attestation hand‑off, and scale/security posture. This document is the contract between the scanning plane and everything else (Policy, Vexer, Feedser, UI, CLI).
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---
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## 0) Mission & boundaries
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**Mission.** Produce **deterministic**, **explainable** SBOMs and diffs for container images and filesystems, quickly and repeatedly, without guessing. Emit two views: **Inventory** (everything present) and **Usage** (entrypoint closure + actually linked libs). Attach attestations through **Signer→Attestor→Rekor v2**.
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**Boundaries.**
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* Scanner **does not** produce PASS/FAIL. The backend (Policy + Vexer + Feedser) decides presentation and verdicts.
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* Scanner **does not** keep third‑party SBOM warehouses. It may **bind** to existing attestations for exact hashes.
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* Core analyzers are **deterministic** (no fuzzy identity). Optional heuristic plug‑ins (e.g., patch‑presence) run under explicit flags and never contaminate the core SBOM.
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---
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## 1) Solution & project layout
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```
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src/
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├─ StellaOps.Scanner.WebService/ # REST control plane, catalog, diff, exports
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├─ StellaOps.Scanner.Worker/ # queue consumer; executes analyzers
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├─ StellaOps.Scanner.Models/ # DTOs, evidence, graph nodes, CDX/SPDX adapters
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├─ StellaOps.Scanner.Storage/ # Mongo repositories; MinIO object client; ILM/GC
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├─ StellaOps.Scanner.Queue/ # queue abstraction (Redis/NATS/RabbitMQ)
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├─ StellaOps.Scanner.Cache/ # layer cache; file CAS; bloom/bitmap indexes
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├─ StellaOps.Scanner.EntryTrace/ # ENTRYPOINT/CMD → terminal program resolver (shell AST)
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├─ StellaOps.Scanner.Analyzers.OS.[Apk|Dpkg|Rpm]/
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├─ StellaOps.Scanner.Analyzers.Lang.[Java|Node|Python|Go|DotNet|Rust]/
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├─ StellaOps.Scanner.Analyzers.Native.[ELF|PE|MachO]/ # PE/Mach-O planned (M2)
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├─ StellaOps.Scanner.Emit.CDX/ # CycloneDX (JSON + Protobuf)
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├─ StellaOps.Scanner.Emit.SPDX/ # SPDX 3.0.1 JSON
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├─ StellaOps.Scanner.Diff/ # image→layer→component three‑way diff
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├─ StellaOps.Scanner.Index/ # BOM‑Index sidecar (purls + roaring bitmaps)
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├─ StellaOps.Scanner.Tests.* # unit/integration/e2e fixtures
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└─ tools/
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├─ StellaOps.Scanner.Sbomer.BuildXPlugin/ # BuildKit generator (image referrer SBOMs)
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└─ StellaOps.Scanner.Sbomer.DockerImage/ # CLI‑driven scanner container
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```
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**Runtime form‑factor:** two deployables
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* **Scanner.WebService** (stateless REST)
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* **Scanner.Worker** (N replicas; queue‑driven)
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---
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## 2) External dependencies
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* **OCI registry** with **Referrers API** (discover attached SBOMs/signatures).
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* **MinIO** (S3‑compatible) for SBOM artifacts; **Object Lock** for immutable classes; **ILM** for TTL.
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* **MongoDB** for catalog, job state, diffs, ILM rules.
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* **Queue** (Redis Streams/NATS/RabbitMQ).
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* **Authority** (on‑prem OIDC) for **OpToks** (DPoP/mTLS).
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* **Signer** + **Attestor** (+ **Fulcio/KMS** + **Rekor v2**) for DSSE + transparency.
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---
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## 3) Contracts & data model
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### 3.1 Evidence‑first component model
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**Nodes**
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* `Image`, `Layer`, `File`
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* `Component` (`purl?`, `name`, `version?`, `type`, `id` — may be `bin:{sha256}`)
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* `Executable` (ELF/PE/Mach‑O), `Library` (native or managed), `EntryScript` (shell/launcher)
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**Edges** (all carry **Evidence**)
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* `contains(Image|Layer → File)`
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* `installs(PackageDB → Component)` (OS database row)
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* `declares(InstalledMetadata → Component)` (dist‑info, pom.properties, deps.json…)
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* `links_to(Executable → Library)` (ELF `DT_NEEDED`, PE imports)
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* `calls(EntryScript → Program)` (file:line from shell AST)
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* `attests(Rekor → Component|Image)` (SBOM/predicate binding)
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* `bound_from_attestation(Component_attested → Component_observed)` (hash equality proof)
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**Evidence**
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```
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{ source: enum, locator: (path|offset|line), sha256?, method: enum, timestamp }
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```
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No confidences. Either a fact is proven with listed mechanisms, or it is not claimed.
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### 3.2 Catalog schema (Mongo)
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* `artifacts`
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```
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{ _id, type: layer-bom|image-bom|diff|index,
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format: cdx-json|cdx-pb|spdx-json,
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bytesSha256, size, rekor: { uuid,index,url }?,
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ttlClass, immutable, refCount, createdAt }
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```
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* `images { imageDigest, repo, tag?, arch, createdAt, lastSeen }`
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* `layers { layerDigest, mediaType, size, createdAt, lastSeen }`
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* `links { fromType, fromDigest, artifactId }` // image/layer -> artifact
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* `jobs { _id, kind, args, state, startedAt, heartbeatAt, endedAt, error }`
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* `lifecycleRules { ruleId, scope, ttlDays, retainIfReferenced, immutable }`
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### 3.3 Object store layout (MinIO)
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```
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layers/<sha256>/sbom.cdx.json.zst
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layers/<sha256>/sbom.spdx.json.zst
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images/<imgDigest>/inventory.cdx.pb # CycloneDX Protobuf
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images/<imgDigest>/usage.cdx.pb
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indexes/<imgDigest>/bom-index.bin # purls + roaring bitmaps
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diffs/<old>_<new>/diff.json.zst
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attest/<artifactSha256>.dsse.json # DSSE bundle (cert chain + Rekor proof)
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```
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---
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## 4) REST API (Scanner.WebService)
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All under `/api/v1/scanner`. Auth: **OpTok** (DPoP/mTLS); RBAC scopes.
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```
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POST /scans { imageRef|digest, force?:bool } → { scanId }
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GET /scans/{id} → { status, imageDigest, artifacts[], rekor? }
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GET /sboms/{imageDigest} ?format=cdx-json|cdx-pb|spdx-json&view=inventory|usage → bytes
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GET /diff?old=<digest>&new=<digest>&view=inventory|usage → diff.json
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POST /exports { imageDigest, format, view, attest?:bool } → { artifactId, rekor? }
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POST /reports { imageDigest, policyRevision? } → { reportId, rekor? } # delegates to backend policy+vex
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GET /catalog/artifacts/{id} → { meta }
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GET /healthz | /readyz | /metrics
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```
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---
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## 5) Execution flow (Worker)
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### 5.1 Acquire & verify
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1. **Resolve image** (prefer `repo@sha256:…`).
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2. **(Optional) verify image signature** per policy (cosign).
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3. **Pull blobs**, compute layer digests; record metadata.
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### 5.2 Layer union FS
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* Apply whiteouts; materialize final filesystem; map **file → first introducing layer**.
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* Windows layers (MSI/SxS/GAC) planned in **M2**.
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### 5.3 Evidence harvest (parallel analyzers; deterministic only)
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**A) OS packages**
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* **apk**: `/lib/apk/db/installed`
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* **dpkg**: `/var/lib/dpkg/status`, `/var/lib/dpkg/info/*.list`
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* **rpm**: `/var/lib/rpm/Packages` (via librpm or parser)
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* Record `name`, `version` (epoch/revision), `arch`, source package where present, and **declared file lists**.
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**B) Language ecosystems (installed state only)**
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* **Java**: `META-INF/maven/*/pom.properties`, MANIFEST → `pkg:maven/...`
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* **Node**: `node_modules/**/package.json` → `pkg:npm/...`
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* **Python**: `*.dist-info/{METADATA,RECORD}` → `pkg:pypi/...`
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* **Go**: Go **buildinfo** in binaries → `pkg:golang/...`
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* **.NET**: `*.deps.json` + assembly metadata → `pkg:nuget/...`
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* **Rust**: crates only when **explicitly present** (embedded metadata or cargo/registry traces); otherwise binaries reported as `bin:{sha256}`.
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> **Rule:** We only report components proven **on disk** with authoritative metadata. Lockfiles are evidence only.
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**C) Native link graph**
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* **ELF**: parse `PT_INTERP`, `DT_NEEDED`, RPATH/RUNPATH, **GNU symbol versions**; map **SONAMEs** to file paths; link executables → libs.
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* **PE/Mach‑O** (planned M2): import table, delay‑imports; version resources; code signatures.
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* Map libs back to **OS packages** if possible (via file lists); else emit `bin:{sha256}` components.
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**D) EntryTrace (ENTRYPOINT/CMD → terminal program)**
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* Read image config; parse shell (POSIX/Bash subset) with AST: `source`/`.` includes; `case/if`; `exec`/`command`; `run‑parts`.
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* Resolve commands via **PATH** within the **built rootfs**; follow language launchers (Java/Node/Python) to identify the terminal program (ELF/JAR/venv script).
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* Record **file:line** and choices for each hop; output chain graph.
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* Unresolvable dynamic constructs are recorded as **unknown** edges with reasons (e.g., `$FOO` unresolved).
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**E) Attestation & SBOM bind (optional)**
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* For each **file hash** or **binary hash**, query local cache of **Rekor v2** indices; if an SBOM attestation is found for **exact hash**, bind it to the component (origin=`attested`).
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* For the **image** digest, likewise bind SBOM attestations (build‑time referrers).
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### 5.4 Component normalization (exact only)
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* Create `Component` nodes only with deterministic identities: purl, or **`bin:{sha256}`** for unlabeled binaries.
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* Record **origin** (OS DB, installed metadata, linker, attestation).
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### 5.5 SBOM assembly & emit
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* **Per‑layer SBOM fragments**: components introduced by the layer (+ relationships).
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* **Image SBOMs**: merge fragments; refer back to them via **CycloneDX BOM‑Link** (or SPDX ExternalRef).
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* Emit both **Inventory** & **Usage** views.
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* Serialize **CycloneDX JSON** and **CycloneDX Protobuf**; optionally **SPDX 3.0.1 JSON**.
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* Build **BOM‑Index** sidecar: purl table + roaring bitmap; flag `usedByEntrypoint` components for fast backend joins.
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### 5.6 DSSE attestation (via Signer/Attestor)
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* WebService constructs **predicate** with `image_digest`, `stellaops_version`, `license_id`, `policy_digest?` (when emitting **final reports**), timestamps.
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* Calls **Signer** (requires **OpTok + PoE**); Signer verifies **entitlement + scanner image integrity** and returns **DSSE bundle**.
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* **Attestor** logs to **Rekor v2**; returns `{uuid,index,proof}` → stored in `artifacts.rekor`.
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---
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## 6) Three‑way diff (image → layer → component)
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### 6.1 Keys & classification
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* Component key: **purl** when present; else `bin:{sha256}`.
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* Diff classes: `added`, `removed`, `version_changed` (`upgraded|downgraded`), `metadata_changed` (e.g., origin from attestation vs observed).
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* Layer attribution: for each change, resolve the **introducing/removing layer**.
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### 6.2 Algorithm (outline)
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```
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A = components(imageOld, key)
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B = components(imageNew, key)
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added = B \ A
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removed = A \ B
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changed = { k in A∩B : version(A[k]) != version(B[k]) || origin changed }
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for each item in added/removed/changed:
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layer = attribute_to_layer(item, imageOld|imageNew)
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usageFlag = usedByEntrypoint(item, imageNew)
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emit diff.json (grouped by layer with badges)
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```
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Diffs are stored as artifacts and feed **UI** and **CLI**.
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---
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## 7) Build‑time SBOMs (fast CI path)
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**Scanner.Sbomer.BuildXPlugin** can act as a BuildKit **generator**:
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* During `docker buildx build --attest=type=sbom,generator=stellaops/sbom-indexer`, run analyzers on the build context/output; attach SBOMs as OCI **referrers** to the built image.
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* Optionally request **Signer/Attestor** to produce **Stella Ops‑verified** attestation immediately; else, Scanner.WebService can verify and re‑attest post‑push.
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* Scanner.WebService trusts build‑time SBOMs per policy, enabling **no‑rescan** for unchanged bases.
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---
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## 8) Configuration (YAML)
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```yaml
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scanner:
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queue:
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kind: redis
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url: "redis://queue:6379/0"
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mongo:
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uri: "mongodb://mongo/scanner"
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s3:
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endpoint: "http://minio:9000"
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bucket: "stellaops"
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objectLock: "governance" # or 'compliance'
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analyzers:
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os: { apk: true, dpkg: true, rpm: true }
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lang: { java: true, node: true, python: true, go: true, dotnet: true, rust: true }
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native: { elf: true, pe: false, macho: false } # PE/Mach-O in M2
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entryTrace: { enabled: true, shellMaxDepth: 64, followRunParts: true }
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emit:
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cdx: { json: true, protobuf: true }
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spdx: { json: true }
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compress: "zstd"
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rekor:
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url: "https://rekor-v2.internal"
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signer:
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url: "https://signer.internal"
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limits:
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maxParallel: 8
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perRegistryConcurrency: 2
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policyHints:
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verifyImageSignature: false
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trustBuildTimeSboms: true
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```
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---
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## 9) Scale & performance
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* **Parallelism**: per‑analyzer concurrency; bounded directory walkers; file CAS dedupe by sha256.
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* **Distributed locks** per **layer digest** to prevent duplicate work across Workers.
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* **Registry throttles**: per‑host concurrency budgets; exponential backoff on 429/5xx.
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* **Targets**:
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* **Build‑time**: P95 ≤ 3–5 s on warmed bases (CI generator).
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* **Post‑build delta**: P95 ≤ 10 s for 200 MB images with cache hit.
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* **Emit**: CycloneDX Protobuf ≤ 150 ms for 5k components; JSON ≤ 500 ms.
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* **Diff**: ≤ 200 ms for 5k vs 5k components.
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---
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## 10) Security posture
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* **AuthN**: Authority‑issued short OpToks (DPoP/mTLS).
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* **AuthZ**: scopes (`scanner.scan`, `scanner.export`, `scanner.catalog.read`).
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* **mTLS** to **Signer**/**Attestor**; only **Signer** can sign.
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* **No network fetches** during analysis (except registry pulls and optional Rekor index reads).
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* **Sandboxing**: non‑root containers; read‑only FS; seccomp profiles; disable execution of scanned content.
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* **Release integrity**: all first‑party images are **cosign‑signed**; Workers/WebService self‑verify at startup.
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---
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## 11) Observability & audit
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* **Metrics**:
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* `scanner.jobs_inflight`, `scanner.scan_latency_seconds`
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* `scanner.layer_cache_hits_total`, `scanner.file_cas_hits_total`
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* `scanner.artifact_bytes_total{format}`
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* `scanner.attestation_latency_seconds`, `scanner.rekor_failures_total`
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* **Tracing**: spans for acquire→union→analyzers→compose→emit→sign→log.
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* **Audit logs**: DSSE requests log `license_id`, `image_digest`, `artifactSha256`, `policy_digest?`, Rekor UUID on success.
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---
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## 12) Testing matrix
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* **Determinism:** given same image + analyzers → byte‑identical **CDX Protobuf**; JSON normalized.
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* **OS packages:** ground‑truth images per distro; compare to package DB.
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* **Lang ecosystems:** sample images per ecosystem (Java/Node/Python/Go/.NET/Rust) with installed metadata; negative tests w/ lockfile‑only.
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* **Native & EntryTrace:** ELF graph correctness; shell AST cases (includes, run‑parts, exec, case/if).
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* **Diff:** layer attribution against synthetic two‑image sequences.
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* **Performance:** cold vs warm cache; large `node_modules` and `site‑packages`.
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* **Security:** ensure no code execution from image; fuzz parser inputs; path traversal resistance on layer extract.
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---
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## 13) Failure modes & degradations
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* **Missing OS DB** (files exist, DB removed): record **files**; do **not** fabricate package components; emit `bin:{sha256}` where unavoidable; flag in evidence.
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* **Unreadable metadata** (corrupt dist‑info): record file evidence; skip component creation; annotate.
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* **Dynamic shell constructs**: mark unresolved edges with reasons (env var unknown) and continue; **Usage** view may be partial.
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* **Registry rate limits**: honor backoff; queue job retries with jitter.
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* **Signer refusal** (license/plan/version): scan completes; artifact produced; **no attestation**; WebService marks result as **unverified**.
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---
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## 14) Optional plug‑ins (off by default)
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* **Patch‑presence detector** (signature‑based backport checks). Reads curated function‑level signatures from advisories; inspects binaries for patched code snippets to lower false‑positives for backported fixes. Runs as a sidecar analyzer that **annotates** components; never overrides core identities.
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* **Runtime probes** (with Zastava): when allowed, compare **/proc/<pid>/maps** (DSOs actually loaded) with static **Usage** view for precision.
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---
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## 15) DevOps & operations
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* **HA**: WebService horizontal scale; Workers autoscale by queue depth & CPU; distributed locks on layers.
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* **Retention**: ILM rules per artifact class (`short`, `default`, `compliance`); **Object Lock** for compliance artifacts (reports, signed SBOMs).
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* **Upgrades**: bump **cache schema** when analyzer outputs change; WebService triggers refresh of dependent artifacts.
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* **Backups**: Mongo (daily dumps); MinIO (versioned buckets, replication); Rekor v2 DB snapshots.
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---
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## 16) CLI & UI touch points
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* **CLI**: `stellaops scan <ref>`, `stellaops diff --old --new`, `stellaops export`, `stellaops verify attestation <bundle|url>`.
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* **UI**: Scan detail shows **Inventory/Usage** toggles, **Diff by Layer**, **Attestation badge** (verified/unverified), Rekor link, and **EntryTrace** chain with file:line breadcrumbs.
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||||
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||||
---
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||||
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## 17) Roadmap (Scanner)
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||||
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* **M2**: Windows containers (MSI/SxS/GAC analyzers), PE/Mach‑O native analyzer, deeper Rust metadata.
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||||
* **M2**: Buildx generator GA (certified external registries), cross‑registry trust policies.
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* **M3**: Patch‑presence plug‑in GA (opt‑in), cross‑image corpus clustering (evidence‑only; not identity).
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||||
* **M3**: Advanced EntryTrace (POSIX shell features breadth, busybox detection).
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||||
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||||
---
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||||
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||||
### Appendix A — EntryTrace resolution (pseudo)
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||||
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||||
```csharp
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||||
ResolveEntrypoint(ImageConfig cfg, RootFs fs):
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||||
cmd = Normalize(cfg.ENTRYPOINT, cfg.CMD)
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||||
stack = [ Script(cmd, path=FindOnPath(cmd[0], fs)) ]
|
||||
visited = set()
|
||||
|
||||
while stack not empty and depth < MAX:
|
||||
cur = stack.pop()
|
||||
if cur in visited: continue
|
||||
visited.add(cur)
|
||||
|
||||
if IsShellScript(cur.path):
|
||||
ast = ParseShell(cur.path)
|
||||
foreach directive in ast:
|
||||
if directive is Source include:
|
||||
p = ResolveInclude(include.path, cur.env, fs)
|
||||
stack.push(Script(p))
|
||||
if directive is Exec call:
|
||||
p = ResolveExec(call.argv[0], cur.env, fs)
|
||||
stack.push(Program(p, argv=call.argv))
|
||||
if directive is Interpreter (python -m / node / java -jar):
|
||||
term = ResolveInterpreterTarget(call, fs)
|
||||
stack.push(Program(term))
|
||||
else:
|
||||
return Terminal(cur.path)
|
||||
|
||||
return Unknown(reason)
|
||||
```
|
||||
|
||||
### Appendix B — BOM‑Index sidecar
|
||||
|
||||
```
|
||||
struct Header { magic, version, imageDigest, createdAt }
|
||||
vector<string> purls
|
||||
map<purlIndex, roaring_bitmap> components
|
||||
optional map<purlIndex, roaring_bitmap> usedByEntrypoint
|
||||
```
|
||||
|
||||
Reference in New Issue
Block a user