I have just setup a GKE (Google Cloud) based Istio Kubernetes cluster and have having some connectivity issues within the cluster.
On hitting the external ip from the outside world I get a 503 Service Unavailable from the gateway
< HTTP/1.1 503 Service Unavailable
< date: Fri, 24 Jan 2020 16:17:27 GMT
< server: istio-envoy
< content-length: 0
Notably it's definitely hitting the cluster. I don't however know where to look next on why the service is showing unavailable.
istioctl proxy-status gives this which could be pertinent:
istio-ingressgateway-5599b67bcb-5ztp6.istio-system SYNCED STALE (Never Acknowledged) SYNCED SYNCED istio-pilot-69c7dc4578-mtm8m 1.1.3*Could you please share with us your deploy, in order to check if you are having issues with Sidecars, or if the issue is related with your replicas.
It seems that my livenessProbe and readynessProbe have a conflict Istio's checks. I noticed an envoy error which stopped the proxy running because the management port was the same as the service port. Again this is new to me but it looks like I'd probably need to specify a extra port for liveness/readyness in Kubernetes land so that Istio doesn't complain.
I disabled my helm/kube liveness/readyness checks and everything burst into life.