Kubernetes Ingress (GCE) keeps returning 502 error

Question

I am trying to setup an Ingress in GCE Kubernetes. But when I visit the IP address and path combination defined in the Ingress, I keep getting the following 502 error:

---

Here is what I get when I run: kubectl describe ing --namespace dpl-staging

Name:           dpl-identity
Namespace:      dpl-staging
Address:        35.186.221.153
Default backend:    default-http-backend:80 (10.0.8.5:8080)
TLS:
  dpl-identity terminates
Rules:
  Host  Path    Backends
  ----  ----    --------
  *
        /api/identity/*     dpl-identity:4000 (<none>)
Annotations:
  https-forwarding-rule:    k8s-fws-dpl-staging-dpl-identity--5fc40252fadea594
  https-target-proxy:       k8s-tps-dpl-staging-dpl-identity--5fc40252fadea594
  url-map:          k8s-um-dpl-staging-dpl-identity--5fc40252fadea594
  backends:         {"k8s-be-31962--5fc40252fadea594":"HEALTHY","k8s-be-32396--5fc40252fadea594":"UNHEALTHY"}
Events:
  FirstSeen LastSeen    Count   From                SubObjectPath   Type        Reason  Message
  --------- --------    -----   ----                -------------   --------    ------  -------
  15m       15m     1   {loadbalancer-controller }          Normal      ADD dpl-staging/dpl-identity
  15m       15m     1   {loadbalancer-controller }          Normal      CREATE  ip: 35.186.221.153
  15m       6m      4   {loadbalancer-controller }          Normal      Service no user specified default backend, using system default

I think the problem is dpl-identity:4000 (<none>). Shouldn't I see the IP address of the dpl-identity service instead of <none>?

Here is my service description: kubectl describe svc --namespace dpl-staging

Name:           dpl-identity
Namespace:      dpl-staging
Labels:         app=dpl-identity
Selector:       app=dpl-identity
Type:           NodePort
IP:             10.3.254.194
Port:           http    4000/TCP
NodePort:       http    32396/TCP
Endpoints:      10.0.2.29:8000,10.0.2.30:8000
Session Affinity:   None
No events.

Also, here is the result of executing: kubectl describe ep -n dpl-staging dpl-identity

Name:       dpl-identity
Namespace:  dpl-staging
Labels:     app=dpl-identity
Subsets:
  Addresses:        10.0.2.29,10.0.2.30
  NotReadyAddresses:    <none>
  Ports:
    Name    Port    Protocol
    ----    ----    --------
    http    8000    TCP

No events.

---

Here is my deployment.yaml:

apiVersion: v1
kind: Secret
metadata:
  namespace: dpl-staging
  name: dpl-identity
type: Opaque
data:
  tls.key: <base64 key>
  tls.crt: <base64 crt>
---
apiVersion: v1
kind: Service
metadata:
  namespace: dpl-staging
  name: dpl-identity
  labels:
    app: dpl-identity
spec:
  type: NodePort
  ports:
    - port: 4000
      targetPort: 8000
      protocol: TCP
      name: http
  selector:
    app: dpl-identity
---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  namespace: dpl-staging
  name: dpl-identity
  labels:
    app: dpl-identity
  annotations:
    kubernetes.io/ingress.allow-http: "false"
spec:
  tls:
  - secretName: dpl-identity
  rules:
  - http:
      paths:
        - path: /api/identity/*
          backend:
            serviceName: dpl-identity
            servicePort: 4000
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  namespace: dpl-staging
  name: dpl-identity
kind: Ingress
metadata:
  namespace: dpl-staging
  name: dpl-identity
  labels:
    app: dpl-identity
  annotations:
    kubernetes.io/ingress.allow-http: "false"
spec:
  tls:
  - secretName: dpl-identity
  rules:
  - http:
      paths:
        - path: /api/identity/*
          backend:
            serviceName: dpl-identity
            servicePort: 4000
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  namespace: dpl-staging
  name: dpl-identity
  labels:
    app: dpl-identity
spec:
  replicas: 2
  strategy:
    type: RollingUpdate
  template:
    metadata:
      labels:
        app: dpl-identity
    spec:
      containers:
      - image: gcr.io/munpat-container-engine/dpl/identity:0.4.9
        name: dpl-identity
        ports:
        - containerPort: 8000
          name: http
        volumeMounts:
        - name: dpl-identity
          mountPath: /data
      volumes:
      - name: dpl-identity
        secret:
          secretName: dpl-identity

Solution 1

Your backend k8s-be-32396--5fc40252fadea594 is showing as "UNHEALTHY".

Ingress will not forward traffic if the backend is UNHEALTHY, this will result in the 502 error you are seeing.

It will be being marked as UNHEALTHY becuase it is not passing it's health check, you can check the health check setting for k8s-be-32396--5fc40252fadea594 to see if they are appropriate for your pod, it may be polling an URI or port that is not returning a 200 response. You can find these setting under Compute Engine > Health Checks.

If they are correct then there are many steps between your browser and the container that could be passing traffic incorrectly, you could try kubectl exec -it PODID -- bash (or ash if you are using Alpine) and then try curl-ing localhost to see if the container is responding as expected, if it is and the health checks are also configured correctly then this would narrow down the issue to likely be with your service, you could then try changing the service from a NodePort type to a LoadBalancer and see if hitting the service IP directly from your browser works.

Solution 2

I was having the same issue. It turns out I had to wait a few minutes before ingress to validate the service health. If someone is going to the same and done all the steps like readinessProbe and linvenessProbe, just ensure your ingress is pointing to a service that is either a NodePort, and wait a few minutes until the yellow warning icon turns into a green one. Also, check the log on StackDriver to get a better idea of what's going on. My readinessProbe and livenessProbe is on /login, for the gce class. So I don't think it has to be on /healthz.

Solution 3

Issue is indeed a health check and seemed "random" for my apps where I used name-based virtual hosts to reverse proxy requests from ingress via domains to two separate backend services. Both were secured using Lets Encrypt and kube-lego. My solution was to standardize the path for health checks for all services sharing an ingress, and declare the readinessProbe and livenessProbe configs in my deployment.yml file.

I faced this issue with Google cloud cluster node version 1.7.8 and found this issue that closely-resembled what I experienced: * https://github.com/jetstack/kube-lego/issues/27

I'm using gce and kube-lego and my backend service health checks were on / and kube-lego is on /healthz. It appears differing paths for health checks with gce ingress might be the cause so it may be worth updating backend services to match the /healthz pattern so all use same (or as one commenter in Github issue stated they updated kube-lego to pass on /).

Solution 4

I had the same issue. I turned out that the pod itself was running ok, which I tested via port-forwarding and accessing the health-check URL.

Port-Forward can be activated in console as follows:

$    kubectl port-forward <pod-name> local-port:pod-port

So if the pod is running ok and ingress still shows unhealthy state there might be an issue with your service configuration. In my case my app-selector was incorrect, causing the selection of a non existent pod. Interestingly this isn't showed as an errors or alerts in google console.

Definition of the pods:

#pod-definition.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: <pod-name>
  namespace: <namespace>
spec:
  selector:
    matchLabels:
      app: **<pod-name>**
  template:
    metadata:
      labels:
        app: <pod-name>
    spec:
    #spec-definition follows

#service.yaml    
apiVersion: v1
    kind: Service
    metadata:
      name: <name-of-service-here>
      namespace: <namespace>
    spec:
      type: NodePort
      selector:
        app: **<pod-name>**
      ports:
      - protocol: TCP
        port: 8080
        targetPort: 8080
        name: <port-name-here>

Solution 5

I had the same problem, and it persisted after I enabled livenessProbe as well readinessPorbe. It turned this was to do with basic auth. I've added basic auth to livenessProbe and the readinessPorbe, but turns out the GCE HTTP(S) load balancer doesn't have a configuration option for that.

There seem to be a few another kind of issue with too, e.g. setting container port to 8080 and service port to 80 didn't work with GKE ingress controller (yet I wouldn't clearly indicate what the problem was). And broadly, it looks to me like there is very little visibility and running your own ingress container is a better option with respect to visibility.

I picked Traefik for my project, it worked out of the box, and I'd like to enable Let's Encrypt integration. The only change I had to make to Traefik manifests was about tweaking the service object to disabling access to the UI from outside of the cluster and expose my app with through external load balancer (GCE TCP LB). Also, Traefik is more native to Kubernetes. I tried Heptio Contour, but something didn't work out of the box (will give it a go next time when the new version comes out).

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