下面演示如何在Kong for Kubernetes加载自定义插件。

先准备自定义插件的Lua代码。

mkdir myheader
cd myheader

vi handler.lua
local MyHeader = {}

MyHeader.PRIORITY = 1000

function MyHeader:header_filter(conf)
  -- do custom logic here
  kong.response.set_header("myheader", conf.header_value)
end

return MyHeader

vi schema.lua
return {
  name = "myheader",
  fields = {
    { config = {
        type = "record",
        fields = {
          { header_value = { type = "string", default = "twingao", }, },
        },
    }, },
  }
}

tree myheader/
myheader/
├── handler.lua
└── schema.lua

创建Configmap或者Secret，将自定义插件myheader加载入Kubernetes。

kubectl create configmap kong-plugin-myheader --from-file=myheader -n kong

或者

kubectl create secret generic kong-plugin-myheader --from-file=myheader

kubectl get cm
NAME                                        DATA   AGE
kong-plugin-myheader                        2      25s

kubectl get secret
NAME                                                 TYPE                                  DATA   AGE
kong-plugin-myheader                                 Opaque                                2      29s

对于按照Kong系列-04-Helm安装Kong 1.3.0 with PostgreSQL and with Ingress Controller使用helm安装的Kong的情况，要加载自定义插件到Kong中，需要修改helm的values.yaml文件的配置，但由于没有搞清楚如何升级应用的部分配置，只能先卸载gateway应用，并删除自动创建的pvc。

helm uninstall gateway

kubectl delete pvc data-gateway-postgresql-0

将kong直接下载下来，并修改values.yaml文件配置。并重新部署Kong。此时会自动加载自定义插件。

helm pull stable/kong --version 0.26.1 --untar

vi kong/values.yaml
# 可以增加到最后面
plugins:
  configMaps:
  - name: kong-plugin-myheader
    pluginName: myheader

或者

plugins:
  secrets:
  - name: kong-plugin-myheader
    pluginName: myheader

helm install gateway kong \
    --set admin.useTLS=false \
    --set admin.nodePort=32444 \
    --set proxy.http.nodePort=32080 \
    --set proxy.tls.nodePort=32443 \
    --set replicaCount=2 \
    --set ingressController.enabled=true \
    --set plugins.configMaps.name=kong-plugin-myheader \
    --set plugins.configMaps.pluginName=myheader
    --set postgresql.persistence.storageClass="nfs-client" \
    --set postgresql.persistence.size=1Gi

通过查看配置，可以看出确实加载自定义插件了。

curl http://192.168.1.55:32444 -s | python -m json.tool
{
......
        "loaded_plugins": {
            "acl": true,
            "aws-lambda": true,
            "azure-functions": true,
            "basic-auth": true,
            "bot-detection": true,
            "correlation-id": true,
            "cors": true,
            "datadog": true,
            "file-log": true,
            "hmac-auth": true,
            "http-log": true,
            "ip-restriction": true,
            "jwt": true,
            "key-auth": true,
            "kubernetes-sidecar-injector": true,
            "ldap-auth": true,
            "loggly": true,

            "myheader": true,   #注意此处

            "oauth2": true,
            "post-function": true,
            "pre-function": true,
            "prometheus": true,
            "proxy-cache": true,
            "rate-limiting": true,
            "request-size-limiting": true,
            "request-termination": true,
            "request-transformer": true,
            "response-ratelimiting": true,
            "response-transformer": true,
            "session": true,
            "statsd": true,
            "syslog": true,
            "tcp-log": true,
            "udp-log": true,
            "zipkin": true
        },
......
}

测试一下效果。

vi myheader-plugin.yaml
apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: myheader-plugin
plugin: myheader

vi echo-server-service.yaml
apiVersion: v1
kind: Service
metadata:
  labels:
    app: echo
  name: echo
spec:
  ports:
  - port: 8080
    name: high
    protocol: TCP
    targetPort: 8080
  selector:
    app: echo
---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: echo
  name: echo
spec:
  replicas: 2
  selector:
    matchLabels:
      app: echo
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: echo
    spec:
      containers:
      - image: e2eteam/echoserver:2.2
        name: echo
        ports:
        - containerPort: 8080
        env:
          - name: NODE_NAME
            valueFrom:
              fieldRef:
                fieldPath: spec.nodeName
          - name: POD_NAME
            valueFrom:
              fieldRef:
                fieldPath: metadata.name
          - name: POD_NAMESPACE
            valueFrom:
              fieldRef:
                fieldPath: metadata.namespace
          - name: POD_IP
            valueFrom:
              fieldRef:
                fieldPath: status.podIP
        resources: {}

vi echo-server-ingress.yaml
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: echo-server-ingress
  annotations:
    plugins.konghq.com: myheader-plugin
spec:
  rules:
  - http:
      paths:
      - path: /bar
        backend:
          serviceName: echo
          servicePort: 80

kubectl apply -f myheader-plugin.yaml
kubectl apply -f echo-server-service.yaml
kubectl apply -f echo-server-ingress.yaml

curl -I http://192.168.1.55:32080/bar
HTTP/1.1 200 OK
Content-Type: text/plain; charset=UTF-8
Connection: keep-alive
Date: Thu, 26 Dec 2019 10:05:24 GMT
Server: echoserver
myheader: twingao       #增加了header
X-Kong-Upstream-Latency: 2
X-Kong-Proxy-Latency: 8
Via: kong/1.3.0