linux_patch_manager/SPEC.md

Linux_Patch_Manager — Specification Document

Document Control

Field	Value
Title	Linux_Patch_Manager — Specification Document
Version	0.0.2
Status	Draft
Last Updated	2026-04-23
Related Docs	REQUIREMENTS.md, ARCHITECTURE.md, README.md

Revision History

Version	Date	Summary
0.0.1	2026-04-21	Initial draft
0.0.2	2026-04-23	Aligned with SDD v0.0.3: portable ASCII diagram, hardware-host encryption at rest, Argon2id / EdDSA / TLS 1.3 called out, Settings page scope expanded (Azure SSO, SMTP, web-UI TLS), IP whitelist enforcement

---

Project Overview

Title: Linux_Patch_Manager Description: Enterprise-class, secure, web-based management interface for controlling patching and updates on Linux servers and workstations Version: 0.0.2 Status: Draft

Scope

In Scope:

• Centralized dashboard for fleet-wide patch status monitoring (5 min health polling, 30 min patch polling, on-demand refresh) with visual alerts for unhealthy/unreachable agents
• Multi-distribution support (Debian/Ubuntu, RHEL/CentOS/Fedora, Alpine, Arch)
• Batch patch operations across multiple hosts
• Maintenance window scheduling (per-device, daily/weekly/monthly recurring + one-time) with immediate-apply override
• Compliance reporting and patch status dashboards (compliance, patch history, vulnerability exposure, audit trail — exportable as CSV and PDF, with charts/graphs in PDF output)
• User management with RBAC
• Secure mTLS communication with Linux Patch API agents (TLS 1.3 only)
• Real-time job status via WebSocket relay
• Host registration (manual FQDN/IP + on-demand CIDR auto-discover)
• Static group-based device organization with group-scoped operator access
• Email notifications (optional, disabled by default, runtime-configurable SMTP)
• Azure SSO configuration GUI with "test connection" action (runtime-configurable)
• Web UI TLS certificate strategy selection (self-signed from internal CA or operator-supplied)

Out of Scope:

• Configuration management (Ansible/Puppet/Chef territory)
• OS provisioning, imaging, or bootstrapping
• Vulnerability scanning (manager consumes CVE data from agents, does not scan)
• Mobile UI / native apps
• Automated certificate distribution to agents
• Agent installation/management (separate concern)
• Webhook/Slack/other external notification integrations
• Multi-instance clustering / automatic horizontal scaling

Objectives

Primary Objective: Provide a centralized web interface to monitor and control patch operations across a fleet of Linux hosts via the Linux Patch API.

Key Goals:

• Fleet-wide visibility into patch status and compliance
• Zero-friction patch deployment via maintenance windows
• Secure-by-design architecture (Rust core, mTLS, MFA, Argon2id, EdDSA JWTs)
• Single-instance simplicity supporting up to 2,500 managed hosts

Constraints

Deployment:

• Single bare metal/VM host running Ubuntu 24.04
• Systemd service management
• Internal network access only (same network as managed agents, no public internet exposure)
• Encryption at rest provided by the hardware host (infrastructure-level); the application does not manage disk encryption

Technical:

• Backend: Rust with Axum framework, Tokio async runtime
• Frontend: React + TypeScript SPA (Vite build)
• Database: PostgreSQL 16+ with SQLx for type-safe queries; migrations via sqlx-cli
• Real-time: Axum native WebSocket support for agent-to-browser relay
• Single-instance design (manual horizontal scaling by dividing clients between multiple Patch Manager hosts if needed)
• Fleet capacity: ~500 typical, up to 2,500 hosts
• PDF generation: printpdf + plotters for charts (in-process, no sidecar)

Security:

• Combination authentication: local accounts + Azure SSO
• MFA required for all users (TOTP or WebAuthn)
• Azure SSO users may use Azure's built-in MFA
• Password hashing: Argon2id
• JWT access tokens signed with EdDSA / Ed25519 (15-minute TTL), 90-day key rotation with 24-hour overlap
• Refresh tokens: opaque, server-side stored, 1-hour inactivity timeout, rotated on use, revocable
• mTLS for all agent communication (TLS 1.3 only)
• HTTPS for web UI (TLS 1.3 only)
• IP whitelist enforcement on all connection points
• Role-based access control:
  • Admin: Full access to manage all aspects of Linux Patch Manager
  • Operator: Can add/remove clients, manage schedules and patches only for devices in their group memberships
  • Groups are static; devices and operators can belong to multiple groups
  • Ungrouped devices can be managed by any operator or admin

Architecture Overview

Management plane web application communicating with Linux Patch API agents on each managed host.

+-----------------------------+
|    Linux Patch Manager      |  <- Web UI (this project)
|     (Management Plane)      |     Rust/Axum + React/TS
|     PostgreSQL + WebSocket  |
+--------------+--------------+
               |
               |  mTLS / REST + WSS (TLS 1.3, port 12443)
       +-------+-------+
       v       v       v
   +------+ +------+ +------+
   | Host | | Host | | Host |  <- Linux Patch API agents
   |  A   | |  B   | |  C   |     (up to 2,500)
   +------+ +------+ +------+

API Integration

Upstream Dependency: Linux Patch API

• All managed device access uses the Linux Patch API
• mTLS certificate-based authentication to agents (TLS 1.3 only)
• Hybrid sync/async operation model (sync for queries, async jobs for patch operations)
• WebSocket streaming for real-time job status from agents
• Base path: /api/v1/, Port: 12443, TLS 1.3 only

Certificate Management

• Internal CA managed by Patch Manager, installed on the same host
• Patch Manager issues and renews client certificates for mTLS communication
• Certificate distribution to managed target clients is manual (server administrators responsible)
• Patch Manager has no direct permissions on managed clients
• Web UI TLS certificate: self-signed from the internal CA by default; operator may supply an external certificate (e.g., infrastructure wildcard) via configuration

User Interface

Pages/Views

1. Dashboard — Fleet overview: patch compliance %, host health summary, pending patches, upcoming maintenance windows. Includes root CA certificate download icon.
2. Hosts — List of all managed hosts with filtering by group, health status, OS, patch status
3. Host Detail — Single host view: system info, installed packages, available patches, job history, maintenance window config. Includes host-specific mTLS certificate download icon.
4. Patch Deployment — Select hosts → review available patches → deploy (queue for window or apply now)
5. Jobs — Real-time job monitoring with WebSocket status updates
6. Maintenance Windows — Create/edit recurring and one-time windows per device
7. Groups — Manage static groups, assign hosts and operators
8. Reports — Generate and export compliance, patch history, vulnerability, audit reports (CSV and PDF with charts)
9. Users — Manage local accounts, MFA setup, group assignments
10. Certificates — View/manage internal CA, issue/renew client certs
11. Settings — System configuration including:
    • Azure SSO setup (tenant ID, client ID/secret, redirect URI, scopes) with "Test Connection" action
    • SMTP configuration (host, port, auth, TLS mode, from-address) with "Send Test Email" action
    • Polling intervals (health, patch data)
    • Web UI TLS certificate strategy (internal CA vs. operator-supplied)
    • IP whitelist management

Error Handling

Agent Communication Failures:

• Mark host as unhealthy in dashboard
• Retry with exponential backoff (3 retries, max 30 minutes between retries)
• Continue processing other hosts without blocking

Patch Job Failures:

• Auto-retry failed patch jobs once if still within the maintenance window
• If retry fails or window has closed, surface failure prominently to operators

Batch Operations with Partial Failures:

• Auto-retry failed hosts once
• If retry fails, report which hosts failed and let operator decide next steps
• Successful hosts proceed normally regardless of failures

Assumptions

• Patch Manager host has network connectivity to all managed agents
• Linux Patch API agent is installed and running on each managed host
• Server administrators manually distribute mTLS and root certificates to managed clients
• PostgreSQL is available on the Patch Manager host
• Server administrators manually distribute mTLS and root certificates to managed clients
• PostgreSQL is available on the Patch Manager host
• Hardware host provides full-disk encryption (no OS-level disk encryption managed by the application)

Dependencies

• Linux Patch API (upstream agent on each managed host)
• PostgreSQL 16+
• Internal CA for mTLS certificates
• Azure AD (optional, for SSO)
• SMTP relay (optional, runtime-configurable, for email notifications)

Audit Logging

Captured Events:

• All user login/logout events (success and failure)
• All patch operations (who triggered, which hosts, what patches, queue vs. immediate)
• All host registration/removal events
• All group membership changes (hosts and users)
• All certificate operations (issue, renew, download, revoke)
• All maintenance window changes
• All configuration changes (including Azure SSO, SMTP, IP whitelist, TLS cert strategy)

Integrity: Hash-chained rows (tamper-evident). Periodic and on-demand verification.

Retention: 6 months