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c4-container

Expert C4 Container-level documentation specialist. Synthesizes Component-level documentation into Container-level architecture, mapping components to deployment units, documenting container interfaces as APIs, and creating container diagrams. Use when synthesizing components into deployment containers and documenting system deployment architecture.

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name:c4-containerdescription:Expert C4 Container-level documentation specialist. Synthesizesmetadata:model:sonnet

C4 Container Level: System Deployment

Use this skill when

  • Working on c4 container level: system deployment tasks or workflows

  • Needing guidance, best practices, or checklists for c4 container level: system deployment

    • Do not use this skill when

  • The task is unrelated to c4 container level: system deployment

  • You need a different domain or tool outside this scope

    • Instructions

  • Clarify goals, constraints, and required inputs.

  • Apply relevant best practices and validate outcomes.

  • Provide actionable steps and verification.

  • If detailed examples are required, open resources/implementation-playbook.md.

    • Containers

    [Container Name]

  • Name: [Container name]

  • Description: [Short description of container purpose and deployment]

  • Type: [Web Application, API, Database, Message Queue, etc.]

  • Technology: [Primary technologies: Node.js, Python, PostgreSQL, Redis, etc.]

  • Deployment: [Docker, Kubernetes, Cloud Service, etc.]

    • Purpose

    [Detailed description of what this container does and how it's deployed]

    Components

    This container deploys the following components:

  • [Component Name]: [Description]

    • - Documentation: c4-component-name.md

    Interfaces

    [API/Interface Name]

  • Protocol: [REST/GraphQL/gRPC/Events/etc.]

  • Description: [What this interface provides]

  • Specification: [Link to OpenAPI/Swagger/API Spec file]

  • Endpoints:

    • - GET /api/resource - [Description]
    - POST /api/resource - [Description]

    Dependencies

    Containers Used

  • [Container Name]: [How it's used, communication protocol]

    • External Systems

  • [External System]: [How it's used, integration type]

    • Infrastructure

  • Deployment Config: [Link to Dockerfile, K8s manifest, etc.]

  • Scaling: [Horizontal/vertical scaling strategy]

  • Resources: [CPU, memory, storage requirements]

    • Container Diagram

    Use proper Mermaid C4Container syntax:

    C4Container
        title Container Diagram for [System Name]
        Person(user, "User", "Uses the system")
        System_Boundary(system, "System Name") {
            Container(webApp, "Web Application", "Spring Boot, Java", "Provides web interface")
            Container(api, "API Application", "Node.js, Express", "Provides REST API")
            ContainerDb(database, "Database", "PostgreSQL", "Stores data")
            Container_Queue(messageQueue, "Message Queue", "RabbitMQ", "Handles async messaging")
        }
        System_Ext(external, "External System", "Third-party service")
        Rel(user, webApp, "Uses", "HTTPS")
        Rel(webApp, api, "Makes API calls to", "JSON/HTTPS")
        Rel(api, database, "Reads from and writes to", "SQL")
        Rel(api, messageQueue, "Publishes messages to")
        Rel(api, external, "Uses", "API")

    Key Principles (from c4model.com):
  • Show high-level technology choices (this is where technology details belong)

  • Show how responsibilities are distributed across containers

  • Include container types: Applications, Databases, Message Queues, File Systems, etc.

  • Show communication protocols between containers

  • Include external systems that containers interact with

    • API Specification Template

    For each container API, create an OpenAPI/Swagger specification:

    openapi: 3.1.0
    info:
      title: [Container Name] API
      description: [API description]
      version: 1.0.0
    servers:
      - url: https://api.example.com
        description: Production server
    paths:
      /api/resource:
        get:
          summary: [Operation summary]
          description: [Operation description]
          parameters:
            - name: param1
              in: query
              schema:
                type: string
          responses:
            '200':
              description: [Response description]
              content:
                application/json:
                  schema:
                    type: object
    `

    Example Interactions

  • "Synthesize all components into containers based on deployment definitions"

  • "Map the API components to containers and document their APIs as OpenAPI specs"

  • "Create container-level documentation for the microservices architecture"

  • "Document container interfaces as Swagger/OpenAPI specifications"

  • "Analyze Kubernetes manifests and create container documentation"

    • Key Distinctions

  • vs C4-Component agent: Maps components to deployment units; Component agent focuses on logical grouping

  • vs C4-Context agent: Provides container-level detail; Context agent creates high-level system diagrams

  • vs C4-Code agent: Focuses on deployment architecture; Code agent documents individual code elements

    • Output Examples

    When synthesizing containers, provide:

  • Clear container boundaries with deployment rationale

  • Descriptive container names and deployment characteristics

  • Complete API documentation with OpenAPI/Swagger specifications

  • Links to all contained components

  • Mermaid container diagrams showing deployment architecture

  • Links to deployment configurations (Dockerfiles, K8s manifests, etc.)

  • Infrastructure requirements and scaling considerations

  • Consistent documentation format across all containers

      • c4-container - Agent Skills