Common Parameters - Douban Helm Charts

This page documents the common parameters that are standardized across all charts in this repository. These parameters follow Helm best practices and provide consistent configuration patterns.

Image Configuration

All charts use a standardized image configuration structure.

image.repository

string

required

Container image repository. Specifies where to pull the Docker image from.Example: nginx, ghcr.io/prymitive/karma, prom/memcached-exporter

image.tag

string

default:""

Image tag to use. If not specified, defaults to the chart’s appVersion.Example: "1.16.0", "v0.85", "latest"

Using an empty string allows the image tag to automatically track the chart’s appVersion, making upgrades easier.

image.pullPolicy

string

default:"IfNotPresent"

Image pull policy for the container.Options:

IfNotPresent: Pull only if the image isn’t already present
Always: Always pull the latest version
Never: Never pull, use local image only

imagePullSecrets

array

default:"[]"

List of secret names to use for pulling private images.Example:

imagePullSecrets:
  - name: myregistrykey
  - name: anotherkey

Example Image Configuration

image:
  repository: nginx
  pullPolicy: IfNotPresent
  tag: "1.21.0"

imagePullSecrets:
  - name: docker-registry-secret

Replica and Scaling Configuration

replicaCount

integer

default:"1"

Number of pod replicas to run. Only applies when autoscaling is disabled.Example: 1, 3, 5

autoscaling.enabled

boolean

default:"false"

Enable horizontal pod autoscaling.

autoscaling.minReplicas

integer

default:"1"

Minimum number of replicas for autoscaling.

autoscaling.maxReplicas

integer

default:"100"

Maximum number of replicas for autoscaling.

autoscaling.targetCPUUtilizationPercentage

integer

default:"80"

Target CPU utilization percentage for autoscaling.

autoscaling.targetMemoryUtilizationPercentage

integer

Target memory utilization percentage for autoscaling (optional).

Example Autoscaling Configuration

replicaCount: 3  # Used only when autoscaling.enabled is false

autoscaling:
  enabled: true
  minReplicas: 2
  maxReplicas: 10
  targetCPUUtilizationPercentage: 75
  targetMemoryUtilizationPercentage: 80

Service Configuration

service.type

string

default:"ClusterIP"

Kubernetes Service type.Options:

ClusterIP: Internal cluster IP (default)
NodePort: Expose on each node’s IP at a static port
LoadBalancer: External load balancer (cloud provider)
ExternalName: Map to an external DNS name

service.port

integer

default:"80"

Service port to expose.Example: 80, 8080, 3000

service.annotations

object

default:"{}"

Annotations to add to the Service resource.Example:

service:
  annotations:
    prometheus.io/scrape: "true"
    prometheus.io/port: "9150"

service.labels

object

default:"{}"

Additional labels to add to the Service.

containerPort

integer

default:"80"

Container port that the application listens on.Example: 80, 8080, 3000, 5001

Example Service Configuration

service:
  type: LoadBalancer
  port: 80
  annotations:
    service.beta.kubernetes.io/aws-load-balancer-type: "nlb"
  labels:
    monitoring: "enabled"

containerPort: 8080

Ingress Configuration

ingress.enabled

boolean

default:"false"

Enable Ingress resource creation.

ingress.className

string

default:""

IngressClass name to use (Kubernetes 1.18+).Example: nginx, traefik, alb

ingress.annotations

object

default:"{}"

Annotations for the Ingress resource.Example:

ingress:
  annotations:
    kubernetes.io/ingress.class: nginx
    cert-manager.io/cluster-issuer: letsencrypt-prod
    nginx.ingress.kubernetes.io/ssl-redirect: "true"

ingress.hosts

array

List of hosts and paths for the Ingress.Structure:

hosts:
  - host: example.com
    paths:
      - path: /
        pathType: ImplementationSpecific

ingress.tls

array

default:"[]"

TLS configuration for the Ingress.Example:

tls:
  - secretName: example-tls
    hosts:
      - example.com

Example Ingress Configuration

ingress:
  enabled: true
  className: nginx
  annotations:
    cert-manager.io/cluster-issuer: letsencrypt-prod
    nginx.ingress.kubernetes.io/force-ssl-redirect: "true"
  hosts:
    - host: myapp.example.com
      paths:
        - path: /
          pathType: Prefix
  tls:
    - secretName: myapp-tls
      hosts:
        - myapp.example.com

HTTPRoute Configuration (Gateway API)

Many charts support the Gateway API HTTPRoute as an alternative to Ingress.

httpRoute.enabled

boolean

default:"false"

Enable Gateway API HTTPRoute creation.

httpRoute.gatewayRef.name

string

default:"envoy-gateway-bundle"

Name of the Gateway to attach to.

httpRoute.gatewayRef.namespace

string

default:"envoy-gateway-system"

Namespace of the Gateway.

httpRoute.reuseIngressConfiguration

boolean

default:"true"

Reuse hostnames from the Ingress configuration.

httpRoute.hostnames

array

default:"[]"

Hostnames for the HTTPRoute (used when reuseIngressConfiguration is false).

httpRoute.extraPaths

array

default:"[]"

Additional HTTPRoute rules.Example:

extraPaths:
  - matches:
      - path:
          type: PathPrefix
          value: /api
    backendRefs:
      - name: api-service
        port: 8080

Example HTTPRoute Configuration

httpRoute:
  enabled: true
  gatewayRef:
    name: my-gateway
    namespace: gateway-system
  reuseIngressConfiguration: false
  hostnames:
    - myapp.example.com
  extraPaths:
    - matches:
        - path:
            type: PathPrefix
            value: /admin
      backendRefs:
        - name: admin-backend
          port: 9090

Resource Limits and Requests

resources

object

default:"{}"

CPU and memory resource requests and limits.Example:

resources:
  limits:
    cpu: 500m
    memory: 512Mi
  requests:
    cpu: 250m
    memory: 256Mi

By default, resources are set to {} to allow charts to run in resource-constrained environments. Always set appropriate limits for production deployments.

Resource Configuration Best Practices

resources:
  # Set limits to prevent resource exhaustion
  limits:
    cpu: 1000m      # 1 CPU core
    memory: 1Gi     # 1 GiB of memory
  # Requests ensure guaranteed resources
  requests:
    cpu: 100m       # 0.1 CPU cores
    memory: 128Mi   # 128 MiB of memory

Scheduling Configuration

nodeSelector

object

default:"{}"

Node labels for pod assignment.Example:

nodeSelector:
  disktype: ssd
  kubernetes.io/arch: amd64

tolerations

array

default:"[]"

Tolerations for pod assignment.Example:

tolerations:
  - key: "key1"
    operator: "Equal"
    value: "value1"
    effect: "NoSchedule"
  - key: "dedicated"
    operator: "Exists"
    effect: "NoExecute"

affinity

object

default:"{}"

Affinity rules for pod assignment.Example:

affinity:
  nodeAffinity:
    requiredDuringSchedulingIgnoredDuringExecution:
      nodeSelectorTerms:
        - matchExpressions:
            - key: kubernetes.io/hostname
              operator: In
              values:
                - node1
                - node2
  podAntiAffinity:
    preferredDuringSchedulingIgnoredDuringExecution:
      - weight: 100
        podAffinityTerm:
          labelSelector:
            matchExpressions:
              - key: app
                operator: In
                values:
                  - myapp
          topologyKey: kubernetes.io/hostname

Example Scheduling Configuration

nodeSelector:
  disktype: ssd
  environment: production

tolerations:
  - key: "dedicated"
    operator: "Equal"
    value: "production"
    effect: "NoSchedule"

affinity:
  podAntiAffinity:
    preferredDuringSchedulingIgnoredDuringExecution:
      - weight: 100
        podAffinityTerm:
          labelSelector:
            matchLabels:
              app: nginx
          topologyKey: kubernetes.io/hostname

ServiceAccount Configuration

serviceAccount.create

boolean

default:"true"

Specifies whether a ServiceAccount should be created.

serviceAccount.annotations

object

default:"{}"

Annotations to add to the ServiceAccount.Example:

serviceAccount:
  annotations:
    eks.amazonaws.com/role-arn: arn:aws:iam::123456789012:role/my-role

serviceAccount.name

string

default:""

The name of the ServiceAccount to use. If not set and create is true, a name is generated using the fullname template.

Example ServiceAccount Configuration

serviceAccount:
  create: true
  annotations:
    eks.amazonaws.com/role-arn: arn:aws:iam::123456789012:role/my-app-role
  name: my-custom-sa

Security Context

podSecurityContext

object

default:"{}"

Security context for the pod.Example:

podSecurityContext:
  runAsNonRoot: true
  runAsUser: 1000
  fsGroup: 2000

securityContext

object

default:"{}"

Security context for the container.Example:

securityContext:
  capabilities:
    drop:
      - ALL
  readOnlyRootFilesystem: true
  runAsNonRoot: true
  runAsUser: 1000

Example Security Configuration

podSecurityContext:
  runAsNonRoot: true
  runAsUser: 1000
  fsGroup: 2000
  seccompProfile:
    type: RuntimeDefault

securityContext:
  allowPrivilegeEscalation: false
  capabilities:
    drop:
      - ALL
  readOnlyRootFilesystem: true

Pod Annotations and Labels

podAnnotations

object

default:"{}"

Annotations to add to pods.Example:

podAnnotations:
  prometheus.io/scrape: "true"
  prometheus.io/port: "9090"

podLabels

object

default:"{}"

Additional labels to add to pods.Example:

podLabels:
  environment: production
  team: platform

Environment Variables

env

array

default:"[]"

Environment variables to add to the container.Example:

env:
  - name: LOG_LEVEL
    value: "info"
  - name: DATABASE_PASSWORD
    valueFrom:
      secretKeyRef:
        name: db-secret
        key: password

Volumes and Volume Mounts

volumes

array

default:"[]"

Additional volumes to add to the pod.Example:

volumes:
  - name: config
    configMap:
      name: my-config
  - name: data
    persistentVolumeClaim:
      claimName: my-pvc

volumeMounts

array

default:"[]"

Additional volume mounts to add to the container.Example:

volumeMounts:
  - name: config
    mountPath: /etc/config
    readOnly: true
  - name: data
    mountPath: /data

Example Volume Configuration

volumes:
  - name: config
    configMap:
      name: app-config
  - name: cache
    emptyDir: {}
  - name: persistent-storage
    persistentVolumeClaim:
      claimName: app-pvc

volumeMounts:
  - name: config
    mountPath: /etc/app
    readOnly: true
  - name: cache
    mountPath: /tmp/cache
  - name: persistent-storage
    mountPath: /var/lib/app

Prometheus Monitoring

ServiceMonitor

serviceMonitor.enabled

boolean

default:"false"

Create a ServiceMonitor resource for Prometheus Operator.

serviceMonitor.namespace

string

Namespace to deploy the ServiceMonitor (defaults to release namespace).

serviceMonitor.interval

string

default:"30s"

Scrape interval for metrics.

serviceMonitor.labels

object

default:"{}"

Additional labels for the ServiceMonitor.Example:

serviceMonitor:
  labels:
    release: prometheus-operator

PrometheusRule

prometheusRule.enabled

boolean

default:"false"

Create PrometheusRule resources for alerting.

prometheusRule.namespace

string

Namespace to deploy the PrometheusRule (defaults to release namespace).

prometheusRule.additionalLabels

object

default:"{}"

Additional labels for the PrometheusRule.Example:

prometheusRule:
  additionalLabels:
    release: prometheus-operator

prometheusRule.rules

array

default:"[]"

Prometheus alerting rules.Example:

prometheusRule:
  rules:
    - alert: HighErrorRate
      expr: rate(http_requests_total{status="500"}[5m]) > 0.05
      for: 5m
      labels:
        severity: warning
      annotations:
        summary: High error rate detected
        description: "Error rate is {{ $value }} errors/sec"

Example Prometheus Configuration

serviceMonitor:
  enabled: true
  namespace: monitoring
  interval: 30s
  labels:
    release: prometheus-operator
  relabelings: []
  metricRelabelings: []

prometheusRule:
  enabled: true
  namespace: monitoring
  additionalLabels:
    release: prometheus-operator
  rules:
    - alert: PodDown
      expr: up{job="myapp"} == 0
      for: 2m
      labels:
        severity: critical
      annotations:
        summary: "Pod {{ $labels.instance }} is down"
        description: "Pod has been down for more than 2 minutes"

Name Overrides

nameOverride

string

default:""

Override the chart name used in resource names.

Use sparingly. This affects the nginx.name helper template.

fullnameOverride

string

default:""

Override the full resource name.

This completely replaces the generated name. Use with caution as it can cause naming conflicts.

Next Steps

See Chart Reference Overview for template patterns
Review Chart Development for creating charts
Check individual chart documentation for chart-specific parameters

Overview

​Image Configuration

​Example Image Configuration

​Replica and Scaling Configuration

​Example Autoscaling Configuration

​Service Configuration

​Example Service Configuration

​Ingress Configuration

​Example Ingress Configuration

​HTTPRoute Configuration (Gateway API)

​Example HTTPRoute Configuration

​Resource Limits and Requests

​Resource Configuration Best Practices

​Scheduling Configuration

​Example Scheduling Configuration

​ServiceAccount Configuration

​Example ServiceAccount Configuration

​Security Context

​Example Security Configuration

​Pod Annotations and Labels

​Environment Variables

​Volumes and Volume Mounts

​Example Volume Configuration

​Prometheus Monitoring

​ServiceMonitor

​PrometheusRule

​Example Prometheus Configuration

​Name Overrides

​Next Steps

Build docs developers (and LLMs) love

Image Configuration

Example Image Configuration

Replica and Scaling Configuration

Example Autoscaling Configuration

Service Configuration

Example Service Configuration

Ingress Configuration

Example Ingress Configuration

HTTPRoute Configuration (Gateway API)

Example HTTPRoute Configuration

Resource Limits and Requests

Resource Configuration Best Practices

Scheduling Configuration

Example Scheduling Configuration

ServiceAccount Configuration

Example ServiceAccount Configuration

Security Context

Example Security Configuration

Pod Annotations and Labels

Environment Variables

Volumes and Volume Mounts

Example Volume Configuration

Prometheus Monitoring

ServiceMonitor

PrometheusRule

Example Prometheus Configuration

Name Overrides

Next Steps