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Kubernetes Ingress Controller
1.2.x
You are browsing documentation for an outdated version. See the latest documentation here.

Debug & Troubleshooting

Debug

Using the flag --v=XX it is possible to increase the level of logging. In particular:

  • --v=3 shows details about the service, Ingress rule, and endpoint changes

Authentication to the Kubernetes API Server

A number of components are involved in the authentication process and the first step is to narrow down the source of the problem, namely whether it is a problem with service authentication or with the kubeconfig file. Both authentications must work:

+-------------+   service          +------------+
|             |   authentication   |            |
+  apiserver  +<-------------------+  ingress   |
|             |                    | controller |
+-------------+                    +------------+

Service authentication

The Ingress controller needs information from API server to configure Kong. Therefore, authentication is required, which can be achieved in two different ways:

  1. Service Account: This is recommended because nothing has to be configured.
    The Ingress controller will use information provided by the system to communicate with the API server.
    See ‘Service Account’ section for details.
  2. Kubeconfig file: In some Kubernetes environments service accounts are not available.
    In this case, a manual configuration is required. The Ingress controller binary can be started with the --kubeconfig flag. The value of the flag is a path to a file specifying how to connect to the API server. Using the --kubeconfig does not require the flag --apiserver-host.
    The format of the file is identical to ~/.kube/config which is used by kubectl to connect to the API server.
    See ‘kubeconfig’ section for details.

Discovering API-server

Using this flag --apiserver-host=http://localhost:8080, it is possible to specify an unsecured API server or reach a remote Kubernetes cluster using kubectl proxy. Please do not use this approach in production.

In the diagram below you can see the full authentication flow with all options, starting with the browser on the lower left hand side.


Kubernetes                                                  Workstation
+---------------------------------------------------+     +------------------+
|                                                   |     |                  |
|  +-----------+   apiserver        +------------+  |     |  +------------+  |
|  |           |   proxy            |            |  |     |  |            |  |
|  | apiserver |                    |  ingress   |  |     |  |  ingress   |  |
|  |           |                    | controller |  |     |  | controller |  |
|  |           |                    |            |  |     |  |            |  |
|  |           |                    |            |  |     |  |            |  |
|  |           |  service account/  |            |  |     |  |            |  |
|  |           |  kubeconfig        |            |  |     |  |            |  |
|  |           +<-------------------+            |  |     |  |            |  |
|  |           |                    |            |  |     |  |            |  |
|  +------+----+      kubeconfig    +------+-----+  |     |  +------+-----+  |
|         |<--------------------------------------------------------|        |
|                                                   |     |                  |
+---------------------------------------------------+     +------------------+

Service Account

If using a service account to connect to the API server, Dashboard expects the file /var/run/secrets/kubernetes.io/serviceaccount/token to be present. It provides a secret token that is required to authenticate with the API server.

Verify with the following commands:

# start a container that contains curl
$ kubectl run test --image=tutum/curl -- sleep 10000

# check that container is running
$ kubectl get pods
NAME                   READY     STATUS    RESTARTS   AGE
test-701078429-s5kca   1/1       Running   0          16s

# check if secret exists
$ kubectl exec test-701078429-s5kca ls /var/run/secrets/kubernetes.io/serviceaccount/
ca.crt
namespace
token

# get service IP of master
$ kubectl get services
NAME         CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
kubernetes   10.0.0.1     <none>        443/TCP   1d

# check base connectivity from cluster inside
$ kubectl exec test-701078429-s5kca -- curl -k https://10.0.0.1
Unauthorized

# connect using tokens
$ TOKEN_VALUE=$(kubectl exec test-701078429-s5kca -- cat /var/run/secrets/kubernetes.io/serviceaccount/token)
$ echo $TOKEN_VALUE
eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3Mi....9A
$ kubectl exec test-701078429-s5kca -- curl --cacert /var/run/secrets/kubernetes.io/serviceaccount/ca.crt -H  "Authorization: Bearer $TOKEN_VALUE" https://10.0.0.1
{
  "paths": [
    "/api",
    "/api/v1",
    "/apis",
    "/apis/apps",
    "/apis/apps/v1alpha1",
    "/apis/authentication.k8s.io",
    "/apis/authentication.k8s.io/v1beta1",
    "/apis/authorization.k8s.io",
    "/apis/authorization.k8s.io/v1beta1",
    "/apis/autoscaling",
    "/apis/autoscaling/v1",
    "/apis/batch",
    "/apis/batch/v1",
    "/apis/batch/v2alpha1",
    "/apis/certificates.k8s.io",
    "/apis/certificates.k8s.io/v1alpha1",
    "/apis/extensions",
    "/apis/extensions/v1beta1",
    "/apis/policy",
    "/apis/policy/v1alpha1",
    "/apis/rbac.authorization.k8s.io",
    "/apis/rbac.authorization.k8s.io/v1alpha1",
    "/apis/storage.k8s.io",
    "/apis/storage.k8s.io/v1beta1",
    "/healthz",
    "/healthz/ping",
    "/logs",
    "/metrics",
    "/swaggerapi/",
    "/ui/",
    "/version"
  ]
}

If it is not working, there are two possible reasons:

  1. The contents of the tokens are invalid. Find the secret name with kubectl get secrets --field-selector=type=kubernetes.io/service-account-token and delete it with kubectl delete secret <name>.
    It will automatically be recreated.
  2. You have a non-standard Kubernetes installation and the file containing the token may not be present.

The API server will mount a volume containing this file, but only if the API server is configured to use the ServiceAccount admission controller.
If you experience this error, verify that your API server is using the ServiceAccount admission controller.
If you are configuring the API server by hand, you can set this with the --admission-control parameter.
Please note that you should use other admission controllers as well. Before configuring this option, please read about admission controllers.

More information:

Kubeconfig

If you want to use a kubeconfig file for authentication, follow the deploy procedure and add the flag --kubeconfig=/etc/kubernetes/kubeconfig.yaml to the deployment

Dumping generated Kong configuration

If the controller generates configuration that it cannot apply to Kong successfully, reviewing the generated configuration manually and/or applying it in a test environment can help locate potential causes.

Under normal operation, the controller does not store generated configuration; it is only sent to Kong’s Admin API. The --dump-config flag enables a diagnostic mode where the controller also saves generated configuration to a temporary file. To use the diagnostic mode:

  1. Set the --dump-config flag (or CONTROLLER_DUMP_CONFIG environment variable) to either enabled or sensitive. enabled produces a redacted configuration that omits certificate configuration and credentials, suitable for sharing with Kong support. sensitive dumps the complete configuration exactly as it is sent to the Admin API.
  2. Check controller logs for the dump location with kubectl logs PODNAME -c ingress-controller | grep "config dumps".
  3. (Optional) Make a change to a Kubernetes resource that you know will reproduce the issue. If you are unsure what change caused the issue originally, you can omit this step.
  4. Copy dumped configuration out of the controller for local review with kubectl cp PODNAME:/path/to/dump/last_bad.json /tmp/last_bad.json -c ingress-controller. If the controller successfully applied configuration before the failure, you can also look at last_good.json.

Once you have dumped configuration, take one of the following approaches to isolate issues:

  • If you know of a specific Kubernetes resource change that reproduces the issue, diffing last_good.json and last_bad.json will show the change the controller is trying to apply unsuccessfully.
  • You can apply dumped configuration via the /config Admin API endpoint (DB-less mode) or using decK (DB-backed mode) to a test instance not managed by the ingress controller. This approach lets you review requests and responses (passing --verbose 2 to decK will show all requests) and add debug Kong Lua code when controller requests result in an unhandled error (500 response).