echo-b-host-67446447f7-chvsp 1/1 Running 0 4m50s host-to-b-multi-node-clusterip-78f9869d75-l8cf8 1/1 Running 0 4m50s host-to-b-multi-node-headless-798949bd5f-vvfff pod-to-b-intra-node-845f955cdc-5nfrt 1/1 Running 0 4m49s pod-to-b-multi-node-clusterip-666594b445-bsn4j 1/1 Running 0 4m49s pod-to-b-multi-node-headless-746f84dff5-prk4w echo-b-host-67446447f7-chvsp 1/1 Running 0 4m50s host-to-b-multi-node-clusterip-78f9869d75-l8cf8 1/1 Running 0 4m50s host-to-b-multi-node-headless-798949bd5f-vvfff

echo-b-host-6b7fc94b7c-xtsff 1/1 Running 0 66s host-to-b-multi-node-clusterip-85476cd779-bpg4b 1/1 Running 0 66s host-to-b-multi-node-headless-dc6c44cb5-8jdz8 pod-to-b-intra-node-nodeport-9b487cf89-6ptrt 1/1 Running 0 65s pod-to-b-multi-node-clusterip-7db5dfdcf7-jkjpw 1/1 Running 0 66s pod-to-b-multi-node-headless-7d44b85d69-mtscc echo-b-host-6b7fc94b7c-xtsff 1/1 Running 0 66s host-to-b-multi-node-clusterip-85476cd779-bpg4b 1/1 Running 0 66s host-to-b-multi-node-headless-dc6c44cb5-8jdz8

echo-b-host-6b7fc94b7c-xtsff 1/1 Running 0 66s host-to-b-multi-node-clusterip-85476cd779-bpg4b 1/1 Running 0 66s host-to-b-multi-node-headless-dc6c44cb5-8jdz8 pod-to-b-intra-node-nodeport-9b487cf89-6ptrt 1/1 Running 0 65s pod-to-b-multi-node-clusterip-7db5dfdcf7-jkjpw 1/1 Running 0 66s pod-to-b-multi-node-headless-7d44b85d69-mtscc echo-b-host-6b7fc94b7c-xtsff 1/1 Running 0 66s host-to-b-multi-node-clusterip-85476cd779-bpg4b 1/1 Running 0 66s host-to-b-multi-node-headless-dc6c44cb5-8jdz8

echo-b-host-f86bd784d-wnh4v 1/1 Running 0 68s host-to-b-multi-node-clusterip-585db65b4d-x74nz 1/1 Running 0 68s host-to-b-multi-node-headless-77c64bc7d8-kgf8p pod-to-b-intra-node-nodeport-8484fb6d89-bwj8q 1/1 Running 0 68s pod-to-b-multi-node-clusterip-f7655dbc8-h5bwk 1/1 Running 0 68s pod-to-b-multi-node-headless-5fd98b9648-5bjj8 echo-b-host-f86bd784d-wnh4v 1/1 Running 0 68s host-to-b-multi-node-clusterip-585db65b4d-x74nz 1/1 Running 0 68s host-to-b-multi-node-headless-77c64bc7d8-kgf8p

echo-b-host-6b7fc94b7c-xtsff 1/1 Running 0 66s host-to-b-multi-node-clusterip-85476cd779-bpg4b 1/1 Running 0 66s host-to-b-multi-node-headless-dc6c44cb5-8jdz8 pod-to-b-intra-node-nodeport-9b487cf89-6ptrt 1/1 Running 0 65s pod-to-b-multi-node-clusterip-7db5dfdcf7-jkjpw 1/1 Running 0 66s pod-to-b-multi-node-headless-7d44b85d69-mtscc echo-b-host-6b7fc94b7c-xtsff 1/1 Running 0 66s host-to-b-multi-node-clusterip-85476cd779-bpg4b 1/1 Running 0 66s host-to-b-multi-node-headless-dc6c44cb5-8jdz8

using a client-side load-balancing library + Headless Services Headless services are to us what ClusterIP services are to common people! However, our KubeDNS was not happy at all with the SRV requests headless services worse. Conclusion: We stopped using headless services and gradually migrated to ClusterIP services 46 The hell of migrating hundreds of services Adopting Istio ● Services are immutable each service migration, we need to: ○ Write the ClusterIP service equivalent ○ Make sure Istio-enabled callers update their config with the ClusterIP service ○ Keep a double standard during migration

namespace. A func�oning Kubernetes DNS is strictly required in order for Cilium to resolve the ClusterIP of the etcd cluster. If either kube-dns or coredns were already running before Cilium was deployed CLUSTER-IP EXTERNAL-IP PORT(S) AGE service/deathstar ClusterIP 10.96.110.8 80/TCP 107 service/kubernetes ClusterIP 10.96.0.1 443/TCP 3m53 Each pod will AGE kafka-service ClusterIP None 9092/TCP 2m kubernetes ClusterIP 10.96.0.1 443/TCP 10m zook ClusterIP 10.97.250.131

balancer) www.my-application.com External Traffic 75% 25% POD POD POD POD S E R V I C E (ClusterIP) 75% 25% POD POD Cross-version Traffic My-data-service Service Demo-canary Service Canary my-application.com External Traffic POD POD POD POD S E R V I C E (ClusterIP) – my-data-svc POD POD S E R V I C E (ClusterIP) – demo-canary-svc ISTIO VIRTUAL SERVICE + Destination Rules ISTIO VIRTUAL

CLUSTER-IP EXTERNAL-IP PORT(S) AGE service/chi-demo-01-demo-0-0 ClusterIP None 8123/TCP,9000/TCP,9009/TCP 37s service/clickhouse-demo-01 AGE service/chi-demo-01-demo-0-0 ClusterIP None 8123/TCP,9000/TCP,9009/ TCP 2m service/chi-demo-01-demo-1-0 ClusterIP None 8123/TCP

namespace. A functioning Kubernetes DNS is strictly required in order for Cilium to resolve the ClusterIP of the etcd cluster. If either kube- dns or coredns were already running before Cilium was deployed CLUSTER-IP EXTERNAL-IP PORT(S) AGE service/deathstar ClusterIP 10.96.110.8 80/TCP 107s service/kubernetes ClusterIP 10.96.0.1 443/TCP 3m53s Each pod AGE kafka-service ClusterIP None 9092/TCP 2m kubernetes ClusterIP 10.96.0.1 443/TCP 10m zook ClusterIP 10.97.250.131