ADI: ingress requires nginx allowSnippetAnnotations set to true

[Annopaolo]

In order for the ADI ingress to work, part of the nginx config is given via the nginx.ingress.kubernetes.io/configuration-snippet annotation. Using such annotation is considered a bad practice because it might introduce vulnerabilities (see kubernetes/kubernetes#126811), and indeed the latest nginx versions (both applicatin and Helm charts) do not allow to use it by default (see kubernetes/ingress-nginx#10452).

Document this (at the very least by adding --set controller.allowSnippetAnnotations=true to the nginx install command) and consider whether it is the case to move all nginx configuration to the related configmap.

[xuxiaowei-com-cn]

The default already exists in configmaps.

[root@center-dev-1 ~]# kubectl -n ingress-nginx get deployments.apps ingress-nginx-controller -o yaml | grep configmap
      {"apiVersion":"apps/v1","kind":"Deployment","metadata":{"annotations":{},"labels":{"app.kubernetes.io/component":"controller","app.kubernetes.io/instance":"ingress-nginx","app.kubernetes.io/name":"ingress-nginx","app.kubernetes.io/part-of":"ingress-nginx","app.kubernetes.io/version":"1.9.1"},"name":"ingress-nginx-controller","namespace":"ingress-nginx"},"spec":{"minReadySeconds":0,"revisionHistoryLimit":10,"selector":{"matchLabels":{"app.kubernetes.io/component":"controller","app.kubernetes.io/instance":"ingress-nginx","app.kubernetes.io/name":"ingress-nginx"}},"strategy":{"rollingUpdate":{"maxUnavailable":1},"type":"RollingUpdate"},"template":{"metadata":{"labels":{"app.kubernetes.io/component":"controller","app.kubernetes.io/instance":"ingress-nginx","app.kubernetes.io/name":"ingress-nginx","app.kubernetes.io/part-of":"ingress-nginx","app.kubernetes.io/version":"1.9.1"}},"spec":{"containers":[{"args":["/nginx-ingress-controller","--publish-service=$(POD_NAMESPACE)/ingress-nginx-controller","--election-id=ingress-nginx-leader","--controller-class=k8s.io/ingress-nginx","--ingress-class=nginx","--configmap=$(POD_NAMESPACE)/ingress-nginx-controller","--validating-webhook=:8443","--validating-webhook-certificate=/usr/local/certificates/cert","--validating-webhook-key=/usr/local/certificates/key"],"env":[{"name":"POD_NAME","valueFrom":{"fieldRef":{"fieldPath":"metadata.name"}}},{"name":"POD_NAMESPACE","valueFrom":{"fieldRef":{"fieldPath":"metadata.namespace"}}},{"name":"LD_PRELOAD","value":"/usr/local/lib/libmimalloc.so"}],"image":"registry.k8s.io/ingress-nginx/controller:v1.9.1@sha256:605a737877de78969493a4b1213b21de4ee425d2926906857b98050f57a95b25","imagePullPolicy":"IfNotPresent","lifecycle":{"preStop":{"exec":{"command":["/wait-shutdown"]}}},"livenessProbe":{"failureThreshold":5,"httpGet":{"path":"/healthz","port":10254,"scheme":"HTTP"},"initialDelaySeconds":10,"periodSeconds":10,"successThreshold":1,"timeoutSeconds":1},"name":"controller","ports":[{"containerPort":80,"name":"http","protocol":"TCP"},{"containerPort":443,"name":"https","protocol":"TCP"},{"containerPort":8443,"name":"webhook","protocol":"TCP"}],"readinessProbe":{"failureThreshold":3,"httpGet":{"path":"/healthz","port":10254,"scheme":"HTTP"},"initialDelaySeconds":10,"periodSeconds":10,"successThreshold":1,"timeoutSeconds":1},"resources":{"requests":{"cpu":"100m","memory":"90Mi"}},"securityContext":{"allowPrivilegeEscalation":true,"capabilities":{"add":["NET_BIND_SERVICE"],"drop":["ALL"]},"runAsUser":101},"volumeMounts":[{"mountPath":"/usr/local/certificates/","name":"webhook-cert","readOnly":true}]}],"dnsPolicy":"ClusterFirst","nodeSelector":{"kubernetes.io/os":"linux"},"serviceAccountName":"ingress-nginx","terminationGracePeriodSeconds":300,"volumes":[{"name":"webhook-cert","secret":{"secretName":"ingress-nginx-admission"}}]}}}}
        - --configmap=$(POD_NAMESPACE)/ingress-nginx-controller
[root@center-dev-1 ~]# 

[root@center-dev-1 ~]# kubectl -n ingress-nginx get configmaps ingress-nginx-controller -o yaml
apiVersion: v1
data:
  allow-snippet-annotations: "true"
kind: ConfigMap
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"v1","data":{"allow-snippet-annotations":"false"},"kind":"ConfigMap","metadata":{"annotations":{},"labels":{"app.kubernetes.io/component":"controller","app.kubernetes.io/instance":"ingress-nginx","app.kubernetes.io/name":"ingress-nginx","app.kubernetes.io/part-of":"ingress-nginx","app.kubernetes.io/version":"1.9.1"},"name":"ingress-nginx-controller","namespace":"ingress-nginx"}}
  creationTimestamp: "2023-10-13T02:25:27Z"
  labels:
    app.kubernetes.io/component: controller
    app.kubernetes.io/instance: ingress-nginx
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
    app.kubernetes.io/version: 1.9.1
  name: ingress-nginx-controller
  namespace: ingress-nginx
  resourceVersion: "32089604"
  uid: 73614794-5de6-4bcd-968e-6ad874c68e20
[root@center-dev-1 ~]#