i've been smashing my head agains this issue, i don't know if it's a bug or just misconfiguration. The situation i have is the following:

Inside my cluster, i have the namespace "testing", which has 2 deployments:

1. Front-end
2. Back-end

Services:

1. front-end-service.local
2. back-end-service.local

Both have their services working properly and an ALB is configured to be accessed from the browser.

1. https://front.example.com
2. https://back.example.com

Inside the cluster, from the front end, i can point the backend with a variable to https://back.example.com, and everything works as expected.

However, i was asked to make that communication INSIDE the cluster, so my first attempt was pointing this time to the backend service from the front-end.

Tried to point at: https://back-end-service.local and received this error:

Reason: CORS request did not succeed

Guessing it was because of TLS, i deployed Istio in the namespace, with mutual TLS enabled in STRICT mode. After opening Kiali, i do see the encrypted communication working, however, still i get the same error.

Testing i did:

If i log into the Front-End pod and try to make a curl https://back.example.com, i get a positive response from my API.

If i do a curl https://back-end-service.local, i get curl: (35) SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol.

So in brief, i can communicate to my back-end going outside the cluster and then going back in but if i try to communicate between services INSIDE, it fails with CORS and SSL error.

My config:

kind: PeerAuthentication
apiVersion: security.istio.io/v1beta1
metadata:
  name: default
  namespace: testing
  selfLink: >-
    /apis/security.istio.io/v1beta1/namespaces/production/peerauthentications/default     
  resourceVersion: '7291'
  generation: 1
  creationTimestamp: '2020-06-06T00:22:24Z'
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: >
      {"apiVersion":"security.istio.io/v1beta1","kind":"PeerAuthentication","metadata":{"annotations":{},"name":"default","namespace":"testing"},"spec":{"mtls":{"mode":"STRICT"}}}
spec:
  selector: ~
  mtls:
    mode: STRICT
  portLevelMtls: ~

Back-End-Service:

kind: Service
apiVersion: v1
metadata:
  name: back-end-service
  namespace: testing
  selfLink: /api/v1/namespaces/testing/services/back-end-service
  uid: dccf1b
  resourceVersion: '7520501'
  creationTimestamp: '2020-05-14T21:48:54Z'
  labels:
    app: back-end
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: >
      {"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"labels":{"app":"back-end"},"name":"back-end-service","namespace":"testing"},"spec":{"ports":[{"name":"http","port":3001,"targetPort":3001}],"selector":{"app":"back-end"}}}
  finalizers:
    - service.kubernetes.io/load-balancer-cleanup
spec:
  ports:
    - name: https
      protocol: TCP
      port: 3001
      targetPort: 3001
      nodePort: 30742
  selector:
    app: back-end
  clusterIP: 192.168.1.1
  type: LoadBalancer
  sessionAffinity: None
  externalTrafficPolicy: Cluster

I've tried to change the name to HTTP and HTTPS to the services but it goes beyond that. Any help would be appreciate it!