Traits

Traits provide operational capabilities to components. They are attached to components and modify how the workload is deployed.

Available Traits

Trait	Description	Applies To
scaler	Horizontal autoscaling	All
ingress	HTTP routing via Traefik	Containerized
volume	Volume mounts	All
vault-secret	Vault secrets injection	All
affinity	Node affinity/spread	All
updatestrategy.nomad.oam.dev	Deployment strategy	All
migration.nomad.oam.dev	Node migration settings	All
servicediscovery.nomad.oam.dev	Consul registration	Containerized

Trait Properties

Scaler Trait

Configures horizontal pod autoscaling:

type: scaler
properties:
  replicas: 3          # Current replicas
  min: 1              # Minimum replicas
  max: 10             # Maximum replicas
  scaleMetric: cpu    # Metric: cpu, memory, custom
  scaleTarget: 70     # Target value (percentage)

Ingress Trait

Configures Traefik HTTP routing:

type: ingress
properties:
  host: example.com          # Domain
  pathPrefix: /api          # Path prefix
  port: 8080                # Backend port
  tls: true                 # Enable TLS
  stripPrefix: true        # Strip path prefix
  middleware:               # Additional middleware
    - rate-limit
    - auth

Volume Trait

Mounts volumes to containers:

type: volume
properties:
  name: data-volume         # Volume name
  type: host | csi         # Volume type
  source: my-volume         # Volume source
  mountPath: /data         # Mount destination
  readOnly: false          # Read-only mount

Vault Secret Trait

Injects secrets from Vault:

type: vault-secret
properties:
  path: secret/data/db-creds    # Vault path
  changeMode: restart          # restart, signal
  changeSignal: SIGTERM        # Signal to send
  env:                         # Field to env mapping
    username: DB_USER
    password: DB_PASS

Affinity Trait

Controls pod scheduling:

type: affinity
properties:
  nodeClass: compute-optimized    # Node class
  cloud: aws                      # Cloud provider
  region: us-east-1              # Region
  nodeMeta:                      # Node metadata
    gpu: "true"
  spread: true                   # Spread across DCs

Update Strategy Trait

Configures deployment strategy:

type: updatestrategy.nomad.oam.dev
properties:
  strategy: rolling              # rolling, canary, blue-green
  maxParallel: 2                 # Parallel updates
  canary: 1                      # Canary count
  healthCheck: checks            # checks, task_states, manual
  minHealthyTime: 30s            # Min healthy duration
  healthyDeadline: 5m            # Healthy deadline
  progressDeadline: 10m         # Progress deadline
  autoRevert: true              # Auto-revert on failure

Migration Trait

Configures node draining behavior:

type: migration.nomad.oam.dev
properties:
  maxParallel: 1                 # Parallel migrations
  healthCheck: checks           # checks, task_states
  minHealthyTime: 15s            # Min healthy duration
  healthyDeadline: 5m            # Healthy deadline

Service Discovery Trait

Configures Consul service registration:

type: servicediscovery.nomad.oam.dev
properties:
  serviceName: my-service       # Service name
  tags:                         # Service tags
    - v1
    - production
  port: http                    # Port label
  check:                        # Health check
    type: http                 # http, tcp, script
    path: /health              # Check path
    interval: 10s              # Check interval
    timeout: 3s                # Check timeout

Attaching Traits

Traits are attached to components in the application:

components:
  - name: web
    type: webservice
    properties:
      image: nginx:latest
    traits:
      - type: scaler
        properties:
          replicas: 3
      - type: ingress
        properties:
          host: example.com
      - type: servicediscovery.nomad.oam.dev
        properties:
          serviceName: web
          tags: [v1, production]