Component Configuration Documentation

Each application must document its deployment and runtime expectations. This documentation acts as the single source of truth for:

• Kubernetes NetworkPolicies (ingress & egress)
• Environment variables and secrets
• Configuration files

Every component must have its own section and follow the structure defined below.

Required Structure Per Component

1. Component Name

The official component name as used in:

• Kubernetes workloads and services
• CI/CD pipelines
• Configuration and monitoring

2. Description

A concise description explaining:

• What the component does
• Its responsibility in the system
• High-level dependencies

3. Network Policy Configuration

This section defines all network access required by the component, including:

• Inbound (Ingress) traffic to the component
• Outbound (Egress) traffic from the component
• Databases, message brokers, and external systems
• Dependencies inside and outside the Kubernetes cluster

This section is the authoritative reference for Kubernetes NetworkPolicy definitions

Inbound (Ingress) Access

Defines which components are allowed to connect to this component.

Source Component	Port

Rules

• If the source component is not deployed inside Kubernetes, reference it by a clear name (e.g. PostgreSQL cluster, External API Gateway).

Outbound (Egress) Access

Defines which components this component connects to.

Target Component	Port

Rules

• All databases and external dependencies must be explicitly listed, External systems must be referenced by descriptive names along side the port of the application they need to access.

4. Environment Variables & Secrets

All environment variables used by the component must be documented, including secrets.

Environment Variable	Example Value	Description

Rules

• Example values must never contain real secrets.
• Optional variables must document default behavior.

5. Configuration File (If Applicable)

If the application supports or requires a configuration file:

• An example configuration file must be provided
• The example must include all supported configuration values
• The expected path of the configuration file must be documented.
• Each field must include clear inline comments explaining:
  • What the value does
  • Accepted values
  • Default behavior (if applicable)

Secret values must never appear in configuration files.

If a configuration value can be provided via multiple sources (for example, an environment variable and a configuration file), this must be explicitly documented.

The documentation must specify:

• All supported sources
• Which source takes precedence
• Behavior when multiple sources are provided

Setting	Environment Variable	Config File Path	Precedence

Example Component Documentation

Component: auth-service

Description

The Authentication Service is responsible for user authentication, token issuance, and credential validation. It relies on PostgreSQL for persistent storage and Redis for caching and session management.

Network Policy Configuration

Inbound (Ingress)

Source Component	Port
api-gateway	8080
internal-admin-ui	8080

Outbound (Egress)

Target Component	Port
PostgreSQL cluster	5432
Redis cluster	6379
external-identity-provider	443

Environment Variables & Secrets

Environment Variable	Example Value	Description
SERVICE_PORT	8080	Port the service listens on
DATABASE_HOST	postgres.prod.internal	PostgreSQL hostname
DATABASE_PORT	5432	PostgreSQL port
DATABASE_NAME	auth_db	Database name
DATABASE_USER	auth_user	Database username
DATABASE_PASSWORD	stored in secret	Database password (secret)
DATABASE_SSL	true	Enables TLS for database connections
REDIS_HOST	redis.prod.internal	Redis hostname
REDIS_PORT	6379	Redis port
JWT_SIGNING_KEY	stored in secret	JWT signing key
TOKEN_EXPIRY_MINUTES	60	Token validity duration
LOG_LEVEL	info	Logging level

Configuration File Example

# Server configuration
server:
  # Port the service listens on
  port: 8080

# Database configuration
database:
  # PostgreSQL hostname
  host: postgres.prod.internal

  # PostgreSQL port
  port: 5432

  # Enables TLS for database connections
  ssl: true

# Redis configuration
redis:
  # Redis hostname
  host: redis.prod.internal

  # Redis port
  port: 6379

# Authentication settings
auth:
  # Token expiry duration in minutes
  tokenExpiryMinutes: 60

# Logging configuration
logging:
  # Supported values: debug | info | warn | error
  level: info

Configuration Source Mapping & Precedence

Setting	Environment Variable	Config File Path	Precedence
Service port	SERVICE_PORT	server.port	Environment variable
Database host	DATABASE_HOST	database.host	Environment variable
Database port	DATABASE_PORT	database.port	Environment variable
Database name	DATABASE_NAME	database.name	Environment variable
Database SSL	DATABASE_SSL	database.ssl	Environment variable
Redis host	REDIS_HOST	redis.host	Environment variable
Redis port	REDIS_PORT	redis.port	Environment variable
Token expiry	TOKEN_EXPIRY_MINUTES	auth.tokenExpiryMinutes	Environment variable
Log level	LOG_LEVEL	logging.level	Environment variable