I have an app deployed on GKE along with istio.

My pod has the following issue (kubectl describe pod)

 Warning  Unhealthy  3m30s (x750 over 28m)  kubelet, gke-nodepool  Readiness probe failed: HTTP probe failed with statuscode: 503

Now in the relevant describe sections:

Containers:
  faros:
    Port:           20000/TCP
    Host Port:      0/TCP
    State:          Running
      Started:      Mon, 02 Sep 2019 19:18:10 +0300
    Last State:     Terminated
      Reason:       Error
      Exit Code:    1
      Started:      Mon, 02 Sep 2019 19:08:03 +0300
      Finished:     Mon, 02 Sep 2019 19:17:39 +0300
    Ready:          True
    Restart Count:  3

  istio-proxy:
    Container ID:  docker://f6701350fb6f1cd3f6823d6c8cfa4ada57139bacadef7cff2e6103f4b36b2b4b
  State:          Running
      Started:      Mon, 02 Sep 2019 18:54:15 +0300
  Ready:          False

The logs of faros (my app):

➢  k logs faros-657c68f74-lxslt -c faros
[ENTRYPOINT] Initializing entrypoint.
[ENTRYPOINT] Checking for non-privileged user.
[ENTRYPOINT] Running command.
 * Running on http://0.0.0.0:20000/ (Press CTRL+C to quit)
127.0.0.1 - - [02/Sep/2019 16:18:15] "GET /health HTTP/1.1" 200 -
127.0.0.1 - - [02/Sep/2019 16:18:16] "GET /ready HTTP/1.1" 200 -

The logs of istio

* failed checking application ports. listeners="0.0.0.0:15090","10.8.63.194:31400","10.8.63.194:15443","10.8.49.0:53","10.8.49.250:8080","10.8.63.194:443","10.8.54.34:443","10.8.48.10:53","10.8.63.194:15032","10.8.63.194:15029","10.8.63.194:15030","10.8.63.194:15031","10.8.48.1:443","10.8.48.180:80","10.8.63.194:15020","10.8.58.47:15011","10.8.54.249:42422","10.8.60.185:11211","10.8.51.133:443","10.8.61.194:443","10.8.58.10:44134","10.8.48.44:443","0.0.0.0:9901","0.0.0.0:15004","0.0.0.0:20001","0.0.0.0:15010","0.0.0.0:9411","0.0.0.0:9091","0.0.0.0:15014","0.0.0.0:8080","0.0.0.0:9090","0.0.0.0:7979","0.0.0.0:3000","0.0.0.0:8060","0.0.0.0:3030","0.0.0.0:80","10.8.33.250:15020","0.0.0.0:15001"
* envoy missing listener for inbound application port: 20000

NAME                    READY   STATUS    RESTARTS   AGE   IP            NODE                                            NOMINATED NODE   READINESS GATES
faros-657c68f74-lxslt   1/2     Running   4          37m   10.8.33.250   gke-nodepool1-   <none>           <none>

Which one of the containers is actually having the issue?

edit: Here is the output of get deploy faros -o yaml

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  annotations:
    deployment.kubernetes.io/revision: "1"
    flux.weave.works/antecedent: mynamespace:helmrelease/faros
  creationTimestamp: "2019-09-02T16:51:45Z"
  generation: 2
  labels:
    app: faros
    chart: faros-0.0.3
    heritage: Tiller
    release: faros
    version: blue
  name: faros
  namespace: mynamespace
  resourceVersion: "14221480"
  selfLink: /apis/extensions/v1beta1/namespaces/mynamespace/deployments/faros
  uid: f28f4688-cda1-11e9-a87a-42010a790808
spec:
  minReadySeconds: 5
  progressDeadlineSeconds: 2147483647
  replicas: 1
  revisionHistoryLimit: 2147483647
  selector:
    matchLabels:
      app: faros
      process: web
      release: faros
  strategy:
    rollingUpdate:
      maxSurge: 100%
      maxUnavailable: 0%
    type: RollingUpdate
  template:
    metadata:
      annotations:
        checksum/configmap: b6311a3639d77e8eb746f0c92fe71c43
        checksum/sealedsecrets: e3b0c44298fc1c149afbf4c8996fb92427a
        checksum/secrets: e3b0c44298fc1c149afbf4c8996fb92
        cluster-autoscaler.kubernetes.io/safe-to-evict: "true"
        readiness.status.sidecar.istio.io/applicationPorts: "5000"
        sidecar.istio.io/inject: "true"
      creationTimestamp: null
      labels:
        app: faros
        process: web
        release: faros
        version: blue
    spec:
      containers:
      - env:
        - name: PROCESS_TYPE
          value: web
        envFrom:
        - configMapRef:
            name: faros
        - secretRef:
            name: faros
        image: gcr.io/myregistry/myimage:tag
        imagePullPolicy: Always
        livenessProbe:
          failureThreshold: 3
          httpGet:
            path: /health
            port: http
            scheme: HTTP
          initialDelaySeconds: 5
          periodSeconds: 3
          successThreshold: 1
          timeoutSeconds: 1
        name: faros
        ports:
        - containerPort: 5000
          name: http
          protocol: TCP
        readinessProbe:
          failureThreshold: 3
          httpGet:
            path: /ready
            port: http
            scheme: HTTP
          initialDelaySeconds: 5
          periodSeconds: 3
          successThreshold: 1
          timeoutSeconds: 1
        resources:
          limits:
            cpu: 150m
            memory: 128Mi
          requests:
            cpu: 150m
            memory: 128Mi
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
      dnsPolicy: ClusterFirst
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext: {}
      terminationGracePeriodSeconds: 30
status:
  conditions:
  - lastTransitionTime: "2019-09-02T16:51:45Z"
    lastUpdateTime: "2019-09-02T16:51:45Z"
    message: Deployment does not have minimum availability.
    reason: MinimumReplicasUnavailable
    status: "False"
    type: Available
  observedGeneration: 2
  replicas: 1
  unavailableReplicas: 1
  updatedReplicas: 1