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:
-
- 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](https://c4model.com/diagrams/container)):
- 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
