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ALB -- Another Load Balancer

ALB (Another Load Balancer) is a Kubernetes Gateway powered by OpenResty with years of production experience from Alauda.

Note: We are in the process of preparing the necessary documentation and refactoring the code for open source. More information and detailed usage will be made available soon.

Advantages

  • Isolation and Multi-Tenant: With ALB operator, multiple ALB instances can be created and managed in one cluster. Each tenant can has a group of dedicated ALB instances.
  • Ingress and Gateway API Support: Users can flexibly choose between Ingress and Gateway API according to their own preferences.
  • Flexible User Defined Traffic Rule: ALB provides a traffic rule DSL that can support more complex traffic matching and distribution scenarios that beyond the capabilities of standard Ingress and Gateway API.
  • Multiple Protocol Support: ALB can manage HTTP, HTTPS, TCP and UDP traffic.

Architecture

Quick Start

Deploy the ALB Operator

  1. Create a kind cluster
  2. helm repo add alb https://alauda.github.io/alb/;helm repo update;helm search repo|grep alb
  3. helm install alb-operator alb/alauda-alb2

Deploy an ALB Instance

cat <<EOF | kubectl apply -f -
apiVersion: crd.alauda.io/v2beta1
kind: ALB2
metadata:
    name: alb-demo
    namespace: kube-system
spec:
    address: "172.20.0.5"  # the ip address of node where alb been deployed
    type: "nginx" 
    config:
        networkMode: host
        loadbalancerName: alb-demo
        projects:
        - ALL_ALL
        replicas: 1
EOF

Rua a Demo Application

cat <<EOF | kubectl apply -f -
apiVersion: apps/v1
kind: Deployment
metadata:
  name: hello-world
  labels:
    k8s-app: hello-world
spec:
  replicas: 1 
  selector:
    matchLabels:
      k8s-app: hello-world
  template:
    metadata:
      labels:
        k8s-app: hello-world
    spec:
      terminationGracePeriodSeconds: 60
      containers:
      - name: hello-world
        image: docker.io/crccheck/hello-world:latest 
        imagePullPolicy: IfNotPresent
---
apiVersion: v1
kind: Service
metadata:
  name: hello-world
  labels:
    k8s-app: hello-world
spec:
  ports:
  - name: http
    port: 80
    targetPort: 8000
  selector:
    k8s-app: hello-world 
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: hello-world
spec:
  rules:
  - http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: hello-world
            port:
              number: 80
EOF

Now you visit the app by curl http://${ip}

Advanced Features

Frontend and Rule

Complex traffic matching and distribution patterns can be configured by Frontend and Rule.
syntax of rule's dslx

apiVersion: crd.alauda.io/v1
kind: Frontend
metadata:
  labels:
    alb2.cpaas.io/name: alb-demo # required, indicate the ALB instance to which this Frontend belongs to
  name: alb-demo-00080
  namespace: kube-system
spec:
  backendProtocol: ""   # http|https 
  certificate_name: ""  # $secret_ns/$secret_name
  port: 80              
  protocol: http        # protocol of this Frontend itself
---
apiVersion: crd.alauda.io/v1
kind: Rule
metadata:
  labels:
    alb2.cpaas.io/frontend: alb-demo-00080  # required, indicate the Frontend to which this rule belongs
    alb2.cpaas.io/name: alb-demo            # required, indicate the ALB to which this rule belongs
  name: alb-demo-00080-topu
  namespace: kube-system
spec:
  backendProtocol: ""                       # as same as Frontend
  certificate_name: ""                      # as same as Frontend
  dslx:                                     # this rule matches url starts with /app-a or /app-b and method is post,and url param's group is vip, and host is *.app.com, and header's location is east-1 or east-2 and has a cookie name is uid, and source IPs come from 1.1.1.1-1.1.1.100
  - type: METHOD
    values:
    - - EQ
      - POST
  - type: URL
    values:
    - - STARTS_WITH
      - /app-a
    - - STARTS_WITH
      - /app-b
  - type: PARAM
    key: group
    values:
    - - EQ
      - vip
  - type: HOST 
    values:
    - - ENDS_WITH
      - .app.com
  - type: HEADER
    key: LOCATION 
    values:
    - - IN
      - east-1
      - east-2
  - type: COOKIE
    key: uid
    values:
    - - EXIST 
  - type: SRC_IP
    values:
    - - RANGE
      - "1.1.1.1"
      - "1.1.1.100"
  enableCORS: false
  priority: 5                              # the lower the number, the higher the priority
  serviceGroup:
    services:
    - name: hello-world
      namespace: default
      port: 80
      weight: 100

Ingress Annotations

Rewrite Request

alb.ingress.cpaas.io/rewrite-request: |
{"headers_remove":["h1"],"headers":{"a":"b"},"headers_add":{"aa": ["bb","cc"]}}

headers_remove: remove the header. headers_add: append to the header instead of overwrite it. headers: set the header.

Rewrite Response

alb.ingress.cpaas.io/rewrite-response: |
{"headers_remove":["h1"],"headers":{"a":"b"},"headers_add":{"aa": ["bb","cc"]}}

headers_remove: remove the header. headers_add: append to the header instead of overwrite it. headers: set the header.

Annotations Compatible with ingress-nginx

nginx.ingress.kubernetes.io/rewrite-target
nginx.ingress.kubernetes.io/enable-cors
nginx.ingress.kubernetes.io/cors-allow-headers
nginx.ingress.kubernetes.io/cors-allow-origin
nginx.ingress.kubernetes.io/backend-protocol
nginx.ingress.kubernetes.io/temporal-redirect
nginx.ingress.kubernetes.io/permanent-redirect
nginx.ingress.kubernetes.io/upstream-vhost
nginx.ingress.kubernetes.io/enable-opentelemetry
nginx.ingress.kubernetes.io/opentelemetry-trust-incoming-spans

Container Network

By default, ALB is deployed as a host network, which has the advantage of direct access via node ip, and the disadvantage that each ALB can only have exclusive access to the node, or you need to manually manage the ALB's ports. But, ALB also supports container network mode deployment and provides external access through Loadbalancer type Service.

apiVersion: crd.alauda.io/v2beta1
kind: ALB2
metadata:
    name: alb-demo
    namespace: kube-system
spec:
    type: "nginx" 
    config:
        networkMode: container           # use container networkmode
        vip:
            enableLbSvc: true            # automatically creates a Service of type LoadBalancer and treats the address assigned to the Service as the address of the ALB
        loadbalancerName: alb-demo
        nodeSelector:
          alb-demo: "true"
        projects:
        - ALL_ALL
        replicas: 1

Gateway API

ALB supports GatewayAPI(v1.0.0) out of box, just set the gatewayClassName to exclusive-gateway when creating gateways.

apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: g1 
  namespace: g1 
spec:
  gatewayClassName:  exclusive-gateway
  listeners:
  - name: http
    port: 80
    protocol: HTTP
    allowedRoutes:
      namespaces:
        from: All