Troubleshooting

Policy Rule to Endpoint Mapping

To determine which policy rules are currently in effect for an endpoint the data from cilium endpoint list and cilium endpoint get can be paired with the data from cilium policy get. cilium endpoint get will list the labels of each rule that applies to an endpoint. The list of labels can be passed to cilium policy get to show that exact source policy. Note that rules that have no labels cannot be fetched alone (a no label cilium policy get returns the complete policy on the node). Rules with the same labels will be returned together.

In the above example, for one of the deathstar pods the endpoint id is 568. We can print all policies applied to it with:

$ # Get a shell on the Cilium pod

$ kubectl exec -ti cilium-88k78 -n kube-system -- /bin/bash

$ # print out the ingress labels
$ # clean up the data
$ # fetch each policy via each set of labels
$ # (Note that while the structure is "...l4.ingress...", it reflects all L3, L4 and L7 policy.

$ cilium endpoint get 568 -o jsonpath='{range ..status.policy.realized.l4.ingress[*].derived-from-rules}{@}{"\n"}{end}'|tr -d '][' | xargs -I{} bash -c 'echo "Labels: {}"; cilium policy get {}'
Labels: k8s:io.cilium.k8s.policy.name=rule1 k8s:io.cilium.k8s.policy.namespace=default
[
  {
    "endpointSelector": {
      "matchLabels": {
        "any:class": "deathstar",
        "any:org": "empire",
        "k8s:io.kubernetes.pod.namespace": "default"
      }
    },
    "ingress": [
      {
        "fromEndpoints": [
          {
            "matchLabels": {
              "any:org": "empire",
              "k8s:io.kubernetes.pod.namespace": "default"
            }
          }
        ],
        "toPorts": [
          {
            "ports": [
              {
                "port": "80",
                "protocol": "TCP"
              }
            ],
            "rules": {
              "http": [
                {
                  "path": "/v1/request-landing",
                  "method": "POST"
                }
              ]
            }
          }
        ]
      }
    ],
    "labels": [
      {
        "key": "io.cilium.k8s.policy.name",
        "value": "rule1",
        "source": "k8s"
      },
      {
        "key": "io.cilium.k8s.policy.namespace",
        "value": "default",
        "source": "k8s"
      }
    ]
  }
]
Revision: 217


$ # repeat for egress
$ cilium endpoint get 568 -o jsonpath='{range ..status.policy.realized.l4.egress[*].derived-from-rules}{@}{"\n"}{end}' | tr -d '][' | xargs -I{} bash -c 'echo "Labels: {}"; cilium policy get {}'

Troubleshooting toFQDNs rules

The effect of toFQDNs may change long after a policy is applied, as DNS data changes. This can make it difficult to debug unexpectedly blocked connections, or transient failures. Cilium provides CLI tools to introspect the state of applying FQDN policy in multiple layers of the daemon:

1. cilium policy get should show the FQDN policy that was imported:

   {
     "endpointSelector": {
       "matchLabels": {
         "any:class": "mediabot",
         "any:org": "empire",
         "k8s:io.kubernetes.pod.namespace": "default"
       }
     },
     "egress": [
       {
         "toFQDNs": [
           {
             "matchName": "api.github.com"
           }
         ]
       },
       {
         "toEndpoints": [
           {
             "matchLabels": {
               "k8s:io.kubernetes.pod.namespace": "kube-system",
               "k8s:k8s-app": "kube-dns"
             }
           }
         ],
         "toPorts": [
           {
             "ports": [
               {
                 "port": "53",
                 "protocol": "ANY"
               }
             ],
             "rules": {
               "dns": [
                 {
                   "matchPattern": "*"
                 }
               ]
             }
           }
         ]
       }
     ],
     "labels": [
       {
         "key": "io.cilium.k8s.policy.derived-from",
         "value": "CiliumNetworkPolicy",
         "source": "k8s"
       },
       {
         "key": "io.cilium.k8s.policy.name",
         "value": "fqdn",
         "source": "k8s"
       },
       {
         "key": "io.cilium.k8s.policy.namespace",
         "value": "default",
         "source": "k8s"
       },
       {
         "key": "io.cilium.k8s.policy.uid",
         "value": "f213c6b2-c87b-449c-a66c-e19a288062ba",
         "source": "k8s"
       }
     ]
   }
   

2. After making a DNS request, the FQDN to IP mapping should be available via cilium fqdn cache list:

   # cilium fqdn cache list
   Endpoint   Source   FQDN                  TTL    ExpirationTime             IPs
   725        lookup   api.github.com.       3600   2023-02-10T18:16:05.842Z   140.82.121.6
   725        lookup   support.github.com.   3600   2023-02-10T18:16:09.371Z   185.199.111.133,185.199.109.133,185.199.110.133,185.199.108.133
   

3. If the traffic is allowed, then these IPs should have corresponding local identities via cilium identity list | grep <IP>:

   # cilium identity list | grep -A 1 140.82.121.6
   16777230   cidr:140.82.121.6/32
        reserved:world